Ancient Greek Philosophy

vase From Thales, who is often considered the first Western philosopher, to the Stoics and Skeptics, ancient Greek philosophy opened the doors to a particular way of thinking that provided the roots for the Western intellectual tradition. Here, there is often an explicit preference for the life of reason and rational thought. We find proto-scientific explanations of the natural world in the Milesian thinkers, and we hear Democritus posit atoms—indivisible and invisible units—as the basic stuff of all matter. With Socrates comes a sustained inquiry into ethical matters—an orientation towards human living and the best life for human beings. With Plato comes one of the most creative and flexible ways of doing philosophy, which some have since attempted to imitate by writing philosophical dialogues covering topics still of interest today in ethics, political thought, metaphysics, and epistemology. Plato’s student, Aristotle, was one of the most prolific of ancient authors. He wrote treatises on each of these topics, as well as on the investigation of the natural world, including the composition of animals. The Hellenists—Epicurus, the Cynics, the Stoics, and the Skeptics—developed schools or movements devoted to distinct philosophical lifestyles, each with reason at its foundation.

With this preference for reason came a critique of traditional ways of living, believing, and thinking, which sometimes caused political trouble for the philosophers themselves. Xenophanes directly challenged the traditional anthropomorphic depiction of the gods, and Socrates was put to death for allegedly inventing new gods and not believing in the gods mandated by the city of Athens. After the fall of Alexander the Great, and because of Aristotle’s ties with Alexander and his court, Aristotle escaped the same fate as Socrates by fleeing Athens. Epicurus, like Xenophanes, claimed that the mass of people is impious, since the people conceive of the gods as little more than superhumans, even though human characteristics cannot appropriately be ascribed to the gods. In short, not only did ancient Greek philosophy pave the way for the Western intellectual tradition, including modern science, but it also shook cultural foundations in its own time.

Presocratic Thought
Socrates
Plato
Aristotle
1. Terminology
2. Psychology
3. Ethics
4. Politics
5. Physics
6. Metaphysics
Hellenistic Thought
Post-Hellenistic Thought
Conclusion
References and Further Reading

1. Presocratic Thought

An analysis of Presocratic thought presents some difficulties. First, the texts we are left with are primarily fragmentary, and sometimes, as in the case of Anaxagoras, we have no more than a sentence’s worth of verbatim words. Even these purportedly verbatim words often come to us in quotation from other sources, so it is difficult, if not impossible, to attribute with certainty a definite position to any one thinker. Moreover, “Presocratic” has been criticized as a misnomer since some of the Presocratic thinkers were contemporary with Socrates and because the name might imply philosophical primacy to Socrates. The term “Presocratic philosophy” is also difficult since we have no record of Presocratic thinkers ever using the word “philosophy.” Therefore, we must approach cautiously any study of presocratic thought.

Presocratic thought marks a decisive turn away from mythological accounts towards rational explanations of the cosmos. Indeed, some Presocratics openly criticize and ridicule traditional Greek mythology, while others simply explain the world and its causes in material terms. This is not to say that the Presocratics abandoned belief in gods or things sacred, but there is a definite turn away from attributing causes of material events to gods, and at times a refiguring of theology altogether. The foundation of Presocratic thought is the preference and esteem given to rational thought over mythologizing. This movement towards rationality and argumentation would pave the way for the course of Western thought.

a. The Milesians

Thales (c.624-c.545 B.C.E.), traditionally considered to be the “first philosopher,” proposed a first principle (arche) of the cosmos: water. Aristotle offers some conjectures as to why Thales might have believed this (Graham 29). First, all things seem to derive nourishment from moisture. Next, heat seems to come from or carry with it some sort of moisture. Finally, the seeds of all things have a moist nature, and water is the source of growth for many moist and living things. Some assert that Thales held water to be a component of all things, but there is no evidence in the testimony for this interpretation. It is much more likely, rather, that Thales held water to be a primal source for all things—perhaps the sine qua non of the world.

Like Thales, Anaximander (c.610-c.545 B.C.E.) also posited a source for the cosmos, which he called the boundless (apeiron). That he did not, like Thales, choose a typical element (earth, air, water, or fire) shows that his thinking had moved beyond sources of being that are more readily available to the senses. He might have thought that, since the other elements seem more or less to change into one another, there must be some source beyond all these—a kind of background upon or source from which all these changes happen. Indeed, this everlasting principle gave rise to the cosmos by generating hot and cold, each of which “separated off” from the boundless. How it is that this separation took place is unclear, but we might presume that it happened via the natural force of the boundless. The universe, though, is a continual play of elements separating and combining. In poetic fashion, Anaximander says that the boundless is the source of beings, and that into which they perish, “according to what must be: for they give recompense and pay restitution to each other for their injustice according to the ordering of time” (F1).

If our dates are approximately correct, Anaximenes (c.546-c.528/5 B.C.E.) could have had no direct philosophical contact with Anaximander. However, the conceptual link between them is undeniable. Like Anaximander, Anaximenes thought that there was something boundless that underlies all other things. Unlike Anaximander, Anaximenes made this boundless thing something definite—air. For Anaximander, hot and cold separated off from the boundless, and these generated other natural phenomena (Graham 79). For Anaximenes, air itself becomes other natural phenomena through condensation and rarefaction. Rarefied air becomes fire. When it is condensed, it becomes water, and when it is condensed further, it becomes earth and other earthy things, like stones (Graham 79). This then gives rise to all other life forms. Furthermore, air itself is divine. Both Cicero and Aetius report that, for Anaximenes, air is God (Graham 87). Air, then, changes into the basic elements, and from these we get all other natural phenomena.

b. Xenophanes of Colophon

Xenophanes (c.570-c.478 B.C.E.) directly and explicitly challenged Homeric and Hesiodic mythology. “It is good,” says Hesiod, “to hold the gods in high esteem,” rather than portraying them in “raging battles, which are worthless” (F2). More explicitly, “Homer and Hesiod have attributed to the gods all things that are blameworthy and disgraceful for human beings: stealing, committing adultery, deceiving each other” (F17). At the root of this poor depiction of the gods is the human tendency towards anthropomorphizing the gods. “But mortals think gods are begotten, and have the clothing, voice and body of mortals” (F19), despite the fact that God is unlike mortals in body and thought. Indeed, Xenophanes famously proclaims that if other animals (cattle, lions, and so forth) were able to draw the gods, they would depict the gods with bodies like their own (F20). Beyond this, all things come to be from earth (F27), not the gods, although it is unclear whence came the earth. The reasoning seems to be that God transcends all of our efforts to make him like us. If everyone paints different pictures of divinity, and many people do, then it is unlikely that God fits into any of those frames. So, holding “the gods in high esteem” at least entails something negative, that is, that we take care not to portray them as super humans.

c. Pythagoras and Pythagoreanism

Ancient thought was left with such a strong presence and legacy of Pythagorean influence, and yet little is known with certainty about Pythagoras of Samos (c.570-c.490 B.C.E.). Many know Pythagoras for his eponymous theorem—the square of the hypotenuse of a right triangle is equal to the sum of the squares of the adjacent sides. Whether Pythagoras himself invented the theorem, or whether he or someone else brought it back from Egypt, is unknown. He developed a following that continued long past his death, on down to Philolaus of Croton (c.470-c.399 B.C.E.), a Pythagorean from whom we may gain some insight into Pythagoreanism. Whether or not the Pythagoreans followed a particular doctrine is up for debate, but it is clear that, with Pythagoras and the Pythagoreans, a new way of thinking was born in ancient philosophy that had a significant impact on Platonic thought.

The Pythagoreans believed in the transmigration of souls. The soul, for Pythagoras, finds its immortality by cycling through all living beings in a 3,000-year cycle, until it returns to a human being (Graham 915). Indeed, Xenophanes tells the story of Pythagoras walking by a puppy who was being beaten. Pythagoras cried out that the beating should cease, because he recognized the soul of a friend in the puppy’s howl (Graham 919). What exactly the Pythagorean psychology entails for a Pythagorean lifestyle is unclear, but we pause to consider some of the typical characteristics reported of and by Pythagoreans.

Plato and Aristotle tended to associate the holiness and wisdom of number—and along with this, harmony and music—with the Pythagoreans (Graham 499). Perhaps more basic than number, at least for Philolaus, are the concepts of the limited and unlimited. Nothing in the cosmos can be without limit (F1), including knowledge (F4). Imagine if nothing were limited, but matter were just an enormous heap or morass. Next, suppose that you are somehow able to gain a perspective of this morass (to do so, there must be some limit that gives you that perspective!). Presumably, nothing at all could be known, at least not with any degree of precision, the most careful observation notwithstanding. Additionally, all known things have number, which functions as a limit of things insofar as each thing is a unity, or composed of a plurality of parts.

d. Heraclitus

Heraclitus of Ephesus (c.540-c.480 B.C.E.) stands out in ancient Greek philosophy not only with respect to his ideas, but also with respect to how those ideas were expressed. His aphoristic style is rife with wordplay and conceptual ambiguities. Heraclitus saw reality as composed of contraries—a reality whose continual process of change is precisely what keeps it at rest.

Fire plays a significant role in his picture of the cosmos. No God or man created the cosmos, but it always was, is, and will be fire. At times it seems as though fire, for Heraclitus, is a primary element from which all things come and to which they return. At others, his comments on fire could easily be seen metaphorically. What is fire? It is at once “need and satiety.” This back and forth, or better yet, this tension and distension is characteristic of life and reality—a reality that cannot function without contraries, such as war and peace. “A road up and down is one and the same” (F38). Whether one travels up the road or down it, the road is the same road. “On those stepping into rivers staying the same other and other waters flow” (F39). In his Cratylus, Plato quotes Heraclitus, via the mouthpiece of Cratylus, as saying that “you could not step twice into the same river,” comparing this to the way everything in life is in constant flux (Graham 158). This, according to Aristotle, supposedly drove Cratylus to the extreme of never saying anything for fear that the words would attempt to freeze a reality that is always fluid, and so, Cratylus merely pointed (Graham 183). So, the cosmos and all things that make it up are what they are through the tension and distention of time and becoming. The river is what it is by being what it is not. Fire, or the ever-burning cosmos, is at war with itself, and yet at peace—it is constantly wanting fuel to keep burning, and yet it burns and is satisfied.

e. Parmenides and Zeno

If it is true that for Heraclitus life thrives and even finds stillness in its continuous movement and change, then for Parmenides of Elea (c.515-c.450 B.C.E.) life is at a standstill. Parmenides was a pivotal figure in Presocratic thought, and one of the most influential of the Presocratics in determining the course of Western philosophy. According to McKirahan, Parmenides is the inventor of metaphysics (157)—the inquiry into the nature of being or reality. While the tenets of his thought have their home in poetry, they are expressed with the force of logic. The Parmenidean logic of being thus sparked a long lineage of inquiry into the nature of being and thinking.

Parmenides recorded his thought in the form of a poem. In it, there are two paths that mortals can take—the path of truth and the path of error. The first path is the path of being or what-is. The right way of thinking is to think of what-is, and the wrong way is to think both what-is and what-is-not. The latter is wrong, simply because non-being is not. In other words, there is no non-being, so properly speaking, it cannot be thought—there is nothing there to think. We can think only what is and, presumably, since thinking is a type of being, “thinking and being are the same” (F3). It is only our long entrenched habits of sensation that mislead us into thinking down the wrong path of non-being. The world, and its appearance of change, thrusts itself upon our senses, and we erroneously believe that what we see, hear, touch, taste, and smell is the truth. But, if non-being is not, then change is impossible, for when anything changes, it moves from non-being to being. For example, for a being to grow tall, it must have at some point not been tall. Since non-being is not and cannot therefore be thought, we are deluded into believing that this sort of change actually happens. Similarly, what-is is one. If there were a plurality, there would be non-being, that is, this would not be that. Parmenides thus argues that we must trust in reason alone.

In the Parmenidean tradition, we have Zeno (c.490-c.430 B.C.E.). As Daniel Graham says, while “Parmenides argues for monism, Zeno argues against pluralism” (Graham 245). Zeno seems to have composed a text wherein he claims to show the absurdity in accepting that there is a plurality of beings, and he also shows that motion is impossible. Zeno shows that if we attempt to count a plurality, we end up with an absurdity. If there were a plurality, then it would be neither more nor less than the number that it would have to be. Thus, there would be a finite number of things. On the other hand, if there were a plurality, then the number would be infinite because there is always something else between existing things, and something else between those, and something else between those, ad infinitum. Thus, if there were a plurality of things, then that plurality would be both infinite and finite in number, which is absurd (F4).

The most enduring paradoxes are those concerned with motion. It is impossible for a body in motion to traverse, say, a distance of twenty feet. In order to do so, the body must first arrive at the halfway point, or ten feet. But in order to arrive there, the body in motion must travel five feet. But in order to arrive there, the body must travel two and a half feet, ad infinitum. Since, then, space is infinitely divisible, but we have only a finite time to traverse it, it cannot be done. Presumably, one could not even begin a journey at all. The “Achilles Paradox” similarly attacks motion saying that swift-footed Achilles will never be able to catch up with the slowest runner, assuming the runner started at some point ahead of Achilles. Achilles must first reach the place where the slow runner began. This means that the slow runner will already be a bit beyond where he began. Once Achilles progresses to the next place, the slow runner is already beyond that point, too. Thus, motion seems absurd.

f. Anaxagoras

Anaxagoras of Clazomenae (c.500-c.428 B.C.E.) had what was, up until that time, the most unique perspective on the nature of matter and the causes of its generation and corruption. Closely predating Plato (Anaxagoras died around the time that Plato was born), Anaxagoras left his impression upon Plato and Aristotle, although they were both ultimately dissatisfied with his cosmology (Graham 309-313). He seems to have been almost exclusively concerned with cosmology and the true nature of all that is around us.

Before the cosmos was as it is now, it was nothing but a great mixture—everything was in everything. The mixture was so thoroughgoing that no part of it was recognizable due to the smallness of each thing, and not even colors were perceptible. He considered matter to be infinitely divisible. That is, because it is impossible for being not to be, there is never a smallest part, but there is always a smaller part. If the parts of the great mixture were not infinitely divisible, then we would be left with a smallest part. Since the smallest part could not become smaller, any attempt at dividing it again would presumably obliterate it.

The most important player in this continuous play of being is mind (nous). Although mind can be in some things, nothing else can be in it—mind is unmixed. We recall that, for Anaxagoras, everything is mixed with everything. There is some portion of everything in anything that we identify. Thus, if anything at all were mixed with mind, then everything would be mixed with mind. This mixture would obstruct mind’s ability to rule all else. Mind is in control, and it is responsible for the great mixture of being. Everlasting mind—the most pure of all things—is responsible for ordering the world.

Anaxagoras left his mark on the thought of both Plato and Aristotle, whose critiques of Anaxagoras are similar. In Plato’s Phaedo, Socrates recounts in brief his intellectual history, citing his excitement over his discovery of Anaxagoras’ thought. He was most excited about mind as an ultimate cause of all. Yet, Socrates complains, Anaxagoras made very little use of mind to explain what was best for each of the heavenly bodies in their motions, or the good of anything else. That is, Socrates seems to have wanted some explanation as to why it is good for all things to be as they are (Graham 309-311). Aristotle, too, complains that Anaxagoras makes only minimal use of his principle of mind. It becomes, as it were, a deus ex machina, that is, whenever Anaxagoras was unable to give any other explanation for the cause of a given event, he fell back upon mind (Graham 311-313). It is possible, as always, that both Plato and Aristotle resort here to a straw man of sorts in order to advance their own positions. Indeed, we have seen that Mind set the great mixture into motion, and then ordered the cosmos as we know it. This is no insignificant feat.

g. Democritus and Atomism

Ancient atomism began a legacy in philosophical and scientific thought, and this legacy was revived and significantly evolved in modern philosophy. In contemporary times, the atom is not the smallest particle. Etymologically, however, atomos is that which is uncut or indivisible. The ancient atomists, Leucippus and Democritus (c.5^th cn B.C.E.), were concerned with the smallest particles in nature that make up reality—particles that are both indivisible and invisible. They were to some degree responding to Parmenides and Zeno by indicating atoms as indivisible sources of motion.

Atoms—the most compact and the only indivisible bodies in nature—are infinite in number, and they constantly move through an infinite void. In fact, motion would be impossible, says Democritus, without the void. If there were no void, the atoms would have nothing through which to move. Atoms take on a variety, perhaps an infinite variety, of shapes. Some are round, others are hooked, and yet others are jagged. They often collide with one another, and often bounce off of one another. Sometimes, though, the shapes of the colliding atoms are amenable to one another, and they come together to form the matter that we identify as the sensible world (F5). This combination, too, would be impossible without the void. Atoms need a background (emptiness) out of which they are able to combine (Graham 531). Atoms then stay together until some larger environmental force breaks them apart, at which point they resume their constant motion (F5). Why certain atoms come together to form a world seems up to chance, and yet many worlds have been, are, and will be formed by atomic collision and coalescence (Graham 551). Once a world is formed, however, all things happen by necessity—the causal laws of nature dictate the course of the natural world (Graham 551-553).

h. The Sophists

Much of what is transmitted to us about the Sophists comes from Plato. In fact, two of Plato’s dialogues are named after Sophists, Protagoras and Gorgias, and one is called simply, The Sophist. Beyond this, typical themes of sophistic thought often make their way into Plato’s work, not the least of which are the similarities between Socrates and the Sophists (an issue explicitly addressed in the Apology and elsewhere). Thus, the Sophists had no small influence on fifth century Greece and Greek thought.

Broadly, the Sophists were a group of itinerant teachers who charged fees to teach on a variety of subjects, with rhetoric as the preeminent subject in their curriculum. A common characteristic among many, but perhaps not all, Sophists seems to have been an emphasis upon arguing for each of the opposing sides of a case. Thus, these argumentative and rhetorical skills could be useful in law courts and political contexts. However, these sorts of skills also tended to earn many Sophists their reputation as moral and epistemological relativists, which for some was tantamount to intellectual fraud.

One of the earliest and most famous Sophists was Protagoras (c. 490-c. 420 BC). Only a handful of fragments of his thought exist, and the bulk of the remaining information about him found in Plato’s dialogues should be read cautiously. He is most famous for the apparently relativistic statement that human beings are “the measure of all things, of things that are that they are, of things that are not that they are not” (F1b). Plato, at least for the purposes of the Protagoras, reads individual relativism out of this statement. For example, if the pool of water feels cold to Henry, then it is in fact cold for Henry, while it might appear warm, and therefore be warm for Jennifer. This example portrays perceptual relativism, but the same could go for ethics as well, that is, if X seems good to Henry, then X is good for him, but it might be bad in Jennifer’s judgment. The problem with this view, however, is that if all things are relative to the observer/judge, then the idea that all things are relative is itself relative to the person who asserts it. The idea of communication is then rendered incoherent since each person has his or her own private meaning.

On the other hand, Protagoras’ statement could be interpreted as species-relative. That is, the question of whether and how things are, and whether and how things are not, is a question that has meaning (ostensibly) only for human beings. Thus, all knowledge is relative to us as human beings, and therefore limited by our being and our capabilities. This reading seems to square with the other of Protagoras’ most famous statements: “Concerning the gods, I cannot ascertain whether they exist or whether they do not, or what form they have; for there are many obstacles to knowing, including the obscurity of the question and the brevity of human life” (F3). It is implied here that knowledge is possible, but that it is difficult to attain, and that it is impossible to attain when the question is whether or not the gods exist. We can also see here that human finitude is a limit not only upon human life but also upon knowledge. Thus, if there is knowledge, it is for human beings, but it is obscure and fragile.

Along with Protagoras was Gorgias (c.485-c.380 B.C.E.), another sophist whose namesake became the title of a Platonic dialogue. Perhaps flashier than Protagoras when it came to rhetoric and speech making, Gorgias is known for his sophisticated and poetic style. He is known also for extemporaneous speeches, taking audience suggestions for possible topics upon which he would speak at length. His most well-known work is On Nature, Or On What-Is-Not wherein he, contrary to Eleatic philosophy, sets out to show that neither being nor non-being is, and that even if there were anything, it could be neither known nor spoken. It is unclear whether this work was in jest or in earnest. If it was in jest, then it was likely an exercise in argumentation as much as it was a gibe at the Eleatics. If it was in earnest, then Gorgias could be seen as an advocate for extreme skepticism, relativism, or perhaps even nihilism (Graham 725).

2. Socrates

Socrates (469-399 B.C.E.) wrote nothing, so what stories and information we have about him come to us primarily from Xenophon (430-354 B.C.E.) and Plato. Both Xenophon and Plato knew Socrates, and wrote dialogues in which Socrates usually figures as the main character, but their versions of certain historical events in Socrates’ life are sometimes incompatible. We cannot be sure if or when Xenophon or Plato is reporting about Socrates with historical accuracy. In some cases, we can be sure that they are intentionally not doing so, but merely using Socrates as a mouthpiece to advance philosophical dialogue (Döring 25). Xenophon, in his Memorobilia, wrote some biographical information about Socrates, but we cannot know how much is fabricated or embellished. When we refer to Socrates, we are typically referring to the Socrates of one of these sources and, more often than not, Plato’s version.

Socrates was the son of a sculptor, Sophroniscus, and grew up an Athenian citizen. He was reported to be gifted with words and was sometimes accused of what Plato later accused Sophists, that is, using rhetorical devices to “make the weaker argument the stronger.” Indeed, Xenophon reports that the Thirty Tyrants forbade Socrates to speak publicly except on matters of practical business because his clever use of words seemed to lead young people astray (Book I, II.33-37). Similarly, Aristophanes presents Socrates as an impoverished sophist whose head was in the clouds to the detriment of his daily, practical life. Moreover, his similarities with the sophists are even highlighted in Plato’s work. Indeed, Socrates’ courtroom speech in Plato’s Apology includes a defense against accusations of sophistry (18c).

While Xenophon and Plato both recognize this rhetorical Socrates, they both present him as a virtuous man who used his skills in argumentation for truth, or at least to help remove himself and his interlocutors from error. The so-called Socratic method, or elenchos, refers to the way in which Socrates often carried out his philosophical practice, a method to which he seems to refer in Plato’s Apology (Benson 180-181). Socrates aimed to expose errors or inconsistencies in his interlocutors’ positions. He did so by asking them questions, often demanding yes-or-no answers, and then reduced their positions to absurdity. He was, in short, aiming for his interlocutor to admit his own ignorance, especially where the interlocutor thought that he knew what he did not in fact know. Thus, many Platonic dialogues end in aporia, an impasse in thought—a place of perplexity about the topic originally under discussion (Brickhouse and Smith 3-4). This is presumably the place from which a thoughtful person can then make a fresh start on the way to seeking truth.

Socrates practiced philosophy openly, did not charge fees for doing so and allowed anyone who wanted to engage with him to do so. Xenophon says:

Socrates lived ever in the open; for early in the morning he went to the public promenades and training-grounds; in the forenoon he was seen in the market; and the rest of the day he passed just where most people were to be met: he was generally talking, and anyone might listen. (Memorabilia, Book I, i.10)

The “talking” that Socrates did was presumably philosophical in nature, and this talk was focused primarily on morality. Indeed, as John Cooper claims in his introduction to Plato: Complete Works, Socrates “denied that he had discovered some new wisdom, indeed that he possessed any wisdom at all,” contrary to his predecessors, such as Anaxagoras and Parmenides. Often his discussions had to do with topics of virtue—justice, courage, temperance, and wisdom (Memorabilia, Book I, i.16). This sort of open practice made Socrates well known but also unpopular, which eventually led to his execution.

Socrates’ elenchos, as he recognizes in Plato’s Apology (from apologia, “defense”), made him unpopular. Lycon (about whom little is known), Anytus (an influential politician in Athens), and Meletus, a poet, accused Socrates of not worshipping the gods mandated by Athens (impiety) and of corrupting the youth through his persuasive power of speech. In his Meno, Plato hints that Anytus was already personally angry with Socrates. Anytus has just warned Socrates to “be careful” in the way he speaks about famous people (94e). Socrates then tells Meno, “I think, Meno, that Anytus is angry, and I am not at all surprised. He thinks…that I am slandering those men, and then he believes himself to be one of them” (95a). This is not surprising, if indeed Socrates practiced philosophy in the way that both Xenophon and Plato report that he did by exposing the ignorance of his interlocutors.

Socrates claims to have ventured down the path of philosophy because of a proclamation from the Oracle at Delphi. Socrates’ enthusiastic follower, Chaerephon, reportedly visited the Oracle at Delphi to ask the god whether anyone among the Athenians was wiser than Socrates. The god replied that no one was wiser than Socrates. Socrates, who claims never to have been wise, wondered what this meant. So, in order to understand better the god’s claim, Socrates questioned Athenians from all social strata about their wisdom. In Plato’s Apology, Socrates claims that most people he questioned claimed to know what they did not in fact know (21-22). As a result of showing so many people their own ignorance, or at least trying to, Socrates became unpopular (23a). This unpopularity is eventually what killed him. To add to his unpopularity, Socrates claimed that the Oracle was right, but only in the respect that he had “human wisdom,” that is, the wisdom to recognize what one does not know, and to know that such wisdom is relatively worthless (23b).

Xenophon, too, wrote his own account of Socrates’ defense. Xenophon attributes the accusation of impiety to Socrates’ daimon, or personal god much like a voice of conscience, who forbade Socrates from doing anything that would not be truly beneficial for him. Both Xenophon (4-7) and Plato (40b) claim that it was this daimon who prevented Socrates from making such a defense as would exonerate him. That is, the daimon did not dissuade Socrates from his sentence of death. In Xenophon’s account, The Oracle claimed that no one was “more free than [Socrates], or more just, or more prudent” (Apology 14). Xenophon’s version might differ from Plato’s since Xenophon, a military leader, wanted to emphasize characteristics Socrates exuded that might also make for good characteristics in a statesman (O’Connor 66). At any rate, Xenophon has Socrates recognize his own unpopularity. Also, like Plato, Xenophon recognizes that Socrates held knowledge of oneself and the recognition of one’s own ignorance in high esteem (Memorabilia, Book III, ix. 6-7).

Socrates practiced philosophy, in an effort to know himself, daily and even in the face of his own death. In Plato’s Crito, in which Crito comes to Socrates’ prison cell to persuade Socrates to escape, Socrates wants to know whether escaping would be just, and imminent death does not deter him from seeking an answer to that question. He and Crito first establish that doing wrong willingly is always bad, and this includes returning wrong for wrong (49b-c). Then, personifying Athenian law, Socrates establishes that escaping prison would be wrong. While he acknowledges that he was wrongly found to be guilty of impiety and corrupting the youth, the legal process itself ran according to law, and to escape would be to “wrong” the laws in which he was raised and to which, by virtue of being a life-long Athenian, he agreed to assent.

Plato’s Phaedo presents us with the story of Socrates’ last day on earth. In it, he famously claims that philosophy is practice for dying and death (64a). Indeed, he spends his final hours with his friends discussing a very relevant and pressing philosophical issue, that is the immortality of the soul. Socrates is presented to us as a man who, even in his final hours, wanted nothing more than to pursue wisdom. In Plato’s Euthyphro, Socrates aims to dissuade Euthyphro from indicting his own father for murder. Euthyphro, a priest, claims that what he is doing—prosecuting a wrongdoer—is pious. Socrates then uses his elenchos to show that Euthyphro does not actually know what piety is. Once he is thoroughly confused and frustrated, Euthyphro says, ““it is a considerable task to acquire any precise knowledge of these things [that is, piety]” (14b). Nevertheless, Euthyphro offers yet another definition of “piety.” Socrates’ response is the key to understanding the dialogue: “You could tell me in far fewer words, if you were willing, the sum of what I asked…You were on the verge of doing so, but you turned away. If you had given that answer, I should now have acquired from you sufficient knowledge of the nature of piety” (14c1-c4). It is, in other words, the very act of philosophizing—the recognizing of one’s own ignorance and the search for wisdom—that is piety. Socrates, we are told, continued this practice even in the final hours of his life.

3. Plato

Plato (427-347 B.C.E.) was the son of Athenian aristocrats. He grew up in a time of upheaval in Athens, especially at the conclusion of the Peloponnesian war, when Athens was conquered by Sparta. Debra Nails says, “Plato would have been 12 when Athens lost her empire with the revolt of the subject allies; 13 when democracy fell briefly to the oligarchy of Four Hundred…; [and]14 when democracy was restored” (2). We cannot be sure when he met Socrates. Although ancient sources report that he became Socrates’ follower at age 18, he might have met Socrates much earlier through the relationship between Socrates and Plato’s uncle, Charmides, in 431 B.C.E. (Taylor 3). He might have known Socrates, too, through his “musical” education, which would have consisted of anything under the purview of the muses, that is, everything from dancing to reading, writing, and arithmetic (Nails 2). He also seems to have spent time with Cratylus, the Heraclitean, which probably had an impact primarily on his metaphysics and epistemology.

Plato had aspirations for the political life, but several untoward events pushed him away from the life of political leadership, not the least of which was Socrates’ trial and conviction. While the authenticity of Plato’s Seventh Letter is debated among scholars, it might give us some insight into Plato’s biography:

At last I came to the conclusion that all existing states are badly governed and the condition of their laws practically incurable, without some miraculous remedy and the assistance of fortune; and I was forced to say, in praise of true philosophy , that from her height alone was it possible to discern what the nature of justice is, either in the state or in the individual, and that the ills of the human race would never end until either those who are sincerely and truly lovers of wisdom [that is, philosophers] come into political power, or the rulers of our cities, by the grace of God, learn true philosophy. (Letter VII)

Plato saw any political regime without the aid of philosophy or fortune as fundamentally corrupt. This attitude, however, did not turn Plato entirely from politics. He visited Sicily three times, where two of these trips were failed attempts at trying to turn the tyrant Dionysius II to the life of philosophy. He thus returned to Athens and focused his efforts on the philosophical education he had begun at his Academy (Nails 5).

a. Background of Plato’s Work

Since Plato wrote dialogues, there is a fundamental difficulty with any effort to identify just what Plato himself thought. Plato never appears in the dialogues as an interlocutor. If he was voicing any of his own thoughts, he did it through the mouthpiece of particular characters in the dialogues, each of which has a particular historical context. Thus, any pronouncement about Plato’s “theory” of this or that must be tentative at best. As John Cooper says,

Although everything any speaker says is Plato’s creation, he also stands before it all as the reader does: he puts before us, the readers, and before himself as well, ideas, arguments, theories, claims, etc. for all of us to examine carefully, reflect on, follow out the implications of—in sum, to use as a springboard for our own further philosophical thought. (Cooper xxii)

Thus, while we can indubitably highlight recurring themes and theoretical insights throughout Plato’s work, we must be wary of committing Plato in any wholesale fashion to a particular view.

b. Metaphysics

Perhaps the most famous of Plato’s metaphysical concepts is his notion of the so-called “forms” or “ideas.” The Greek words that we translate as “form” or “idea” are eidos and idea. Both of these words are rooted in verbs of seeing. Thus, the eidos of something is its look, shape, or form. But, as many philosophers do, Plato manipulates this word and has it refer to immaterial entities. Why is it that one can recognize that a maple is a tree, an oak is a tree, and a Japanese fir is a tree? What is it that unites all of our concepts of various trees under a unitary category of Tree? It is the form of “tree” that allows us to understand anything about each and every tree, but Plato does not stop there.

The forms can be interpreted not only as purely theoretical entities, but also as immaterial entities that give being to material entities. Each tree, for example, is what it is insofar as it participates in the form of Tree. Each human being, for example, is different from the next, but each human being is human to the extent that he/she participates in the form of Human Being. This material-immaterial emphasis seems directed ultimately towards Plato’s epistemology. That is, if anything can be known, it is the forms. Since things in the world are changing and temporal, we cannot know them; therefore, forms are unchanging and eternal beings that give being to all changing and temporal beings in the world, if knowledge is to be certain and clear. In other words, we cannot know something that is different from one moment to the next. The forms are therefore pure ideas that unify and stabilize the multiplicity of changing beings in the material world.

The forms are the ultimate reality, and this is shown to us in the Allegory of the Cave. In discussing the importance of education for a city, Socrates produces the Allegory of the Cave in Plato’s Republic (514a-518b). We are to imagine a cave wherein lifelong prisoners dwell. These prisoners do not know that they are prisoners since they have been held captive their entire lives. They are shackled such that they are incapable of turning their heads. Behind them is a fire, and small puppets or trinkets of various things—horses, stones, people, and so forth—are being moved in front of the fire. Shadows of these trinkets are cast onto a wall in front of the prisoners. The prisoners take this world of shadows to be reality since it is the only thing they ever see.

If, however, we suppose that one prisoner is unshackled and is forced to make his way out of the cave, we can see the process of education. At first, the prisoner sees the fire, which casts the shadows he formerly took to be reality. He is then led out of the cave. After his eyes painfully adjust to the sunlight, he first sees only the shadows of things, and then the things themselves. After this, he realizes that it is the sun by which he sees the things, and which gives life to the things he sees. The sun is here analogous to the form of the Good, which is what gives life to all beings and enables us most truly to know all beings.

The concept of the forms is criticized in Plato’s Parmenides. This dialogue shows us a young Socrates, whose understanding of the forms is being challenged by Parmenides. Parmenides first challenges the young Socrates about the scope of the forms. It seems absurd, thinks Parmenides, to suppose stones, hair, or bits of dirt of their own form (130c-d). He then presents the famous “third man” argument. The forms are supposed to be unitary. The multiplicity of large material things, for example, participate in the one form of Largeness, which itself does not participate in anything else. Parmenides argues against this unity: “So another form of largeness will make its appearance, which has emerged alongside largeness itself and the things that partake of it, and in turn another over all these, by which all of them will be large. Each of your forms will no longer be one, but unlimited in multitude” (132a-b). In other words, is the form of Largeness itself large? If so, it would need to participate in another form of Largeness, which would itself need to participate in another form, and so forth.

In short, we can see that Plato is tentative about what is now considered his most important theory. Indeed, in his Seventh Letter, Plato says that talking about the forms at all is a difficult matter. “These things…because of the weakness of language, are just as much concerned with making clear the particular property of each object as the being of it. On this account no sensible man will venture to express his deepest thoughts in words, especially in a form which is unchangeable, as is true of written outlines” (343). The forms are beyond words or, at best, words can only approximately reveal the truth of the forms. Yet, Plato seems to take it on faith that, if there is knowledge to be had, there must be these unchanging, eternal beings.

c. Epistemology

We can say that, for Plato, if there is to be knowledge, it must be of eternal, unchanging things. The world is constantly in flux. It is therefore strange to say that one has knowledge of it, when one can also claim to have knowledge of, say, arithmetic or geometry, which are stable, unchanging things, according to Plato. That is, it seems absurd that one’s ideas about changing things are on a par with one’s ideas about unchanging things. Moreover, like Cratylus, we might wonder whether our ideas about the changing world are ever accurate at all. Our ideas, after all, tend to be much like a photograph of a world, but unlike the photograph, the world continues to change. Thus, Plato reserves the forms as those things about which we can have true knowledge.

How we get knowledge is difficult. The problem of acquiring knowledge gave rise to “Meno’s Paradox” in Plato’s Meno. In their search for the nature of virtue, Meno asks Socrates, “How will you look for [virtue], Socrates, when you do not know at all what it is? How will you aim to search for something you do not know at all? If you should meet with it, how will you know that this is the thing that you did not know?” (Meno, 80d-e). If one wants to know X, this implies that he/she does not know X now. If so, then it seems that one cannot even begin to ask about X. In other words, it seems that one must already know X in order to ask about it in the first place, but if one already knows X, then there is nothing to ask. Even if one could ask, one would not know when he/she has the answer since one did not know what he/she was looking for in the first place.

Socrates answers this “debaters argument” with the theory of recollection, claiming that he has heard others talk about this “divine matter” (81a). The theory of recollection rests upon the assumption that the human soul is immortal. The soul’s immortality entails, says Socrates, that the soul has seen and known all things since it has always been. Somehow, the soul “forgets” these things upon its incarnation, and the task of knowledge is to recollect them (81b-e). This, of course, is a poor argument, but Plato knows this, given his preface that it is a “divine matter,” and Socrates’ insistence that we must believe it (not know it or be certain of it) rather than the paradox Meno mentions. Thus, Socrates famously goes on to show recollection in action through a series of questions posed to Meno’s slave. Through a series of leading questions, Meno’s slave provides the answer to a geometrical problem that he did not previously know—or more precisely, he recollects knowledge that he had previously forgotten. We might imagine that this is akin to the “light bulb” moment when something we did not previously understand suddenly becomes clear. At any rate, Socrates shows Meno how the human mind mysteriously, when led in the proper fashion, can arrive at knowledge on its own. This is recollection.

Again, the forms are the most knowable beings and, so, presumably are those beings that we recollect in knowledge. Plato offers another image of knowing in his Republic. True understanding (noesis) is of the forms. Below this, there is thought (dianoia), through which we think about things like mathematics and geometry. Below this is belief (pistis), where we can reason about things that we sense in our world. The lowest rung of the ladder is imagination (eikasia), where our mind is occupied with mere shadows of the physical world (509d-511e). The image of the Divided Line is parallel to the process of the prisoner emerging from the cave in the Allegory of the Cave, and to the Sun/Good analogy. In any case, real knowledge is knowledge of the forms, and is that for which the true philosopher strives, and the philosopher does this by living the life of the best part of the soul—reason.

d. Psychology

Plato is famous for his theory of the tripartite soul (psyche), the most thorough formulation of which is in the Republic. The soul is at least logically, if not also ontologically, divided into three parts: reason (logos), spirit (thumos), and appetite or desire (epithumia). Reason is responsible for rational thought and will be in control of the most ordered soul. Spirit is responsible for spirited emotions, like anger. Appetites are responsible not only for natural appetites such as hunger, thirst, and sex, but also for the desire of excess in each of these and other appetites. Why are the three separate, according to Plato? The argument for the distinction between three parts of the soul rests upon the Principle of Contradiction.

Socrates says, “It is obvious that the same thing will not be willing to do or undergo opposites in the same part of itself, in relation to the same thing, at the same time. So, if we ever find this happening in the soul, we’ll know that we aren’t dealing with one thing but many” (Republic, 436b6-c1). Thus, for example, the appetitive part of the soul is responsible for someone’s thirst. Just because, however, that person might desire a drink, it does not mean that she will drink at that time. In fact, it is conceivable that, for whatever reason, she will restrain herself from drinking at that time. Since the Principle of Contradiction entails that the same part of the soul cannot, at the same time and in the same respect, desire and not desire to drink, it must be some other part of the soul that helps reign in the desire (439b). The rational part of the soul is responsible for keeping desires in check or, as in the case just mentioned, denying the fulfillment of desires when it is appropriate to do so.

Why is the spirited part different from the appetitive part? To answer this question, Socrates relays a story he once heard about a man named Leontius. Leontius “was going up from the Piraeus along the outside of the North Wall when he saw some corpses lying at the executioner’s feet. He had an appetite to look at them bat at the same time he was disgusted and turned away” (Republic, 439e6-440a3). Despite his disgust (issuing from the spirited part of the soul) with his desire, Leontius reluctantly looked at the corpses. Socrates also cites examples when someone has done something, on account of appetite, for which he later reproaches himself. The reproach is rooted in an alliance between reason and spirit. Reason knows that indulging in the appetite is bad, and spirit, on reason’s behalf, becomes angry (440a6-440b4). Reason, with the help of spirit, will rule in the best souls. Appetite, and perhaps to some degree spirit, will rule in a disordered soul. The life of philosophy is a cultivation of reason and its rule.

The soul is also immortal, and one the more famous arguments for the immortality of the soul comes from the Phaedo. This argument rests upon a theory of the relationship of opposites. Hot and cold, for example, are opposites, and there are processes of becoming between the two. Hot comes to be what it is from cold. Cold must also come to be what it is from the hot, otherwise all things would move only in one direction, so to speak, and everything would therefore be hot. Life and death are also opposites. Living things come to be dead and death comes from life. But, since the processes between opposites cannot be a one-way affair, life must also come from death (Phaedo 71c-e2). Presumably Plato means by “death” here the realm of non-earthly existence. The souls must always exist in order to be immortal. We can see here the influence of Pythagorean thought upon Plato since this also leaves room for the transmigration of souls. The disordered souls in which desire rules will return from death to life embodied as animals such as donkeys while unjust and ambitious souls will return as hawks (81e-82a3). The philosopher’s soul is closest to divinity and a life with the gods.

e. Ethics and Politics

It is relatively easy to see, then, where Plato’s psychology intersects with his ethics. The best life is the life of philosophy, that is the life of loving and pursuing wisdom—a life spent engaging logos. The philosophical life is also the most excellent life since it is the touchstone of true virtue. Without wisdom, there is only a shadow or imitation of virtue, and such lives are still dominated by passion, desire, and emotions. On the other hand,

The soul of the philosopher achieves a calm from such emotions; it follows reason and ever stays with it contemplating the true, the divine, which is not the object of opinion. Nurtured by this, it believes that one should live in this manner as long as one is alive and, after death, arrive at what is akin and of the same kind, and escape from human evils. (Phaedo 84a-b)

It is the philosopher, too, who must rule the ideal city, as we saw in Plato’s seventh letter. Just as the philosopher’s soul is ruled by reason, the ideal city must be ruled by philosophers.

The Republic begins with the question of what true justice is. Socrates proposes that he and his interlocutors, Glaucon and Adeimantus, might see justice more clearly in the individual if they take a look at justice writ large in a city, assuming that an individual is in some way analogous to a city (368c-369a). So, Socrates and his interlocutors theoretically create an ideal city, which has three social strata: guardians, auxiliaries, and craftspeople/farmers. The guardians will rule, the auxiliaries will defend the city, and the craftspeople and farmers will produce goods and food for the city. The guardians, as we learn in Book VI, will also be philosophers since only the wisest should rule.

This tripartite city mirrors the tripartite soul. When the guardians/philosophers rule properly, and when the other two classes do their proper work—and do not do or attempt to do work that is not properly their own—the city will be just, much as a soul is just when reason rules (433a-b). How is it that auxiliaries and craftspeople can be kept in their own proper position and be prevented from an ambitious quest for upward movement? Maintaining social order depends not only upon wise ruling, but also upon the Noble Lie. The Noble Lie is a myth that the gods mixed in various metals with the members of the various social strata. The guardians were mixed with gold, the auxiliaries with silver, and the farmers and craftspeople with iron and bronze (415a-c). Since the gods intended for each person to belong to the social class that he/she currently does, it would be an offense to the gods for a member of a social class to attempt to become a member of a different social class.

The most salient concern here is that Plato’s ideal city quickly begins to sound like a fascist state. He even seems to recognize this at times. For example, the guardians must not only go through a rigorous training and education regimen, but they must also live a strictly communal life with one another, having no private property. Adeimantus objects to this saying that the guardians will be unhappy. Socrates’ reply is that they mean to secure happiness for the whole city, not for each individual (419a-420b). Individuality seems lost in Plato’s city.

In anticipation that such a city is doomed to failure, Plato has it dissolve, but he merely cites discord among the rulers (545d) and natural processes of becoming as the reasons for its devolution. Socrates says, “It is hard for a city composed in this way to change, but everything that comes into being must decay. Not even a constitution such as this will last forever. It, too, must face dissolution” (546a1-4). We may notice here that Plato cites human fragility and finitude as sources of the ideal city’s devolution, not the city’s possible fascistic tendencies. Yet, it is possible that the lust for power is the cause of strife and discord among the leaders. In other words, perhaps not even the best sort of education and training can keep even the wisest of human rulers free from desire.

It is difficult to overlook the sometimes moralistic and fascistic tendencies in Plato’s ethical and political thought. Yet, just as he challenges his own metaphysical ideas, he also at times loosens up on his ethical and political ideals. In Phaedo, for example, Plato has Phaedo recount the story of Socrates’ final day. Phaedo says that he and other friends of Socrates arrived at the prison early, and when they were granted access to Socrates, Xanthippe, Socrates’ wife was already there with their infant son (60a), which means that Xanthippe had been there all night. Socrates, to his own pleasure, rubs his legs after the shackles have been removed (60b), which implies that even philosophers enjoy bodily pleasures. Again, Phaedo says that Socrates had a way of easing the distress of those around him—in this case, the distress of Socrates’ imminent death. Phaedo recounts how Socrates eased his pain on that particular day:

I happened to be sitting on his right by the couch on a low stool, so that he was sitting well above me. He stroked my head and pressed the hair on the back of my neck, for he was in the habit of playing with my hair at times. (89a9-b3)

Plato, with these dramatic details, is reminding us that even the philosopher is embodied and, at least to some extent, enjoys that embodiment, even though reason is to rule above all else.

4. Aristotle

Aristotle (384-322 B.C.E.) was born Stagirus, which was a Thracian coastal city. He was the son of Nichomacus, the Macedonian court physician, which allowed for a lifelong connection with the court of Macedonia. When he was 17, Aristotle was sent to Athens to study at Plato’s Academy, which he did for 20 years. After serving as tutor for the young Alexander (later Alexander the Great), Aristotle returned to Athens and started his own school, the Lyceum. Aristotle walked as he lectured, and his followers therefore later became known as the peripatetics, those who walked around as they learned. When Alexander died in 323, and the pro-Macedonian government fell in Athens, a strong anti-Macedonian reaction occurred, and Aristotle was accused of impiety. He fled Athens to Chalcis, where he died a year later.

Unlike Plato, Aristotle wrote treatises, and he was a prolific writer indeed. He wrote several treatises on ethics, he wrote on politics, he first codified the rules of logic, he investigated nature and even the parts of animals, and his Metaphysics is in a significant way a theology. His thought, and particularly his physics, reigned supreme in the Western world for centuries after his death.

a. Terminology

Aristotle used, and sometimes invented, technical vocabulary in nearly all facets of his philosophy. It is important to have an understanding of this vocabulary in order to understand his thought in general. Like Plato, Aristotle talked about forms, but not in the same way as his master. For Aristotle, forms without matter do not exist. I can contemplate the form of human being (that is, what it means to be human), but this would be impossible if actual (embodied) human beings were non-existent. A particular human being, what Aristotle might call “a this,” is hylomorphic, or matter (hyle) joined with form (morphe). Similarly, we cannot sense or make sense of unformed matter. There is no matter in itself. Matter is the potential to take shape through form. Thus, Aristotle is often characterized as the philosopher of earth, while Plato’s gaze is towards the heavens, as it appears in Raphael’s famous School of Athens painting.

Form is thus both the physical shape, but also the idea by which we best know particular beings. Form is the actuality of matter, which is pure potentiality. “Actuality” and “potentiality” are two important terms for Aristotle. A thing is in potentiality when it is not yet what it can inherently or naturally become. An acorn is potentially an oak tree, but insofar as it is an acorn, it is not yet actually an oak tree. When it is an oak tree, it will have reached its actuality—its continuing activity of being a tree. The form of oak tree, in this case, en-forms the wood, and gives it shape—makes it actuality a tree, and not just a heap of matter.

When a being is in actuality, it has fulfilled its end, its telos. All beings by nature are telic beings. The end or telos of an acorn is to become an oak tree. The acorn’s potentiality is an inner striving towards its fulfillment as an oak tree. If it reaches this fulfillment it is in actuality, or entelecheia, which is a word that Aristotle coined, and is etymologically related to telos. It is the activity of being-its-own-end that is actuality. This is also the ergon, or function or work, of the oak tree. The best sort of oak tree—the healthiest, for example—best fulfills its work or function. It does this in its activity, its energeia, of being. This activity or energeia is the en-working or being-at-work of the being.

One more important set of technical terms is Aristotle’s four causes: material, formal, efficient (moving), and final cause. To know a thing thoroughly is to know its cause (aitia), or what is responsible for making a being who or what it is. For instance, we might think of the causes of a house. The material cause is the bricks, mortar, wood, and any other material that goes to make up the house. Yet, these materials could not come together as a house without the formal cause that gives shape to it. The formal cause is the idea of the house in the architect’s soul. The efficient cause would be the builders of the house. The final cause that for which the house exists in the first place, namely shelter, comfort, warmth, and so forth. We will see that the concept of causes, especially final cause, is very important for Aristotle, especially in his argument for the unmoved mover in the Physics.

b. Psychology

Aristotle’s On The Soul (Peri Psyche, often translated in the Latin, De Anima) gives us insight into Aristotle’s conception of the composition of the soul. The soul is the actuality of a body. Alternatively, since matter is in potentiality, and form is actuality, the soul as form is the actuality of the body (412a20-23). Form and matter are never found separately from one another, although we can make a logical distinction between them. For Aristotle, all living things are en-souled beings. Soul is the animating principle (arche) of any living being (a self-nourishing, growing and decaying being). Thus, even plants are en-souled (413a26). Without soul, a body would not be alive, and a plant, for instance, would be a plant in name only.

There are three types of soul: nutritive, sensitive, and intellectual. Some beings have only one of these, or some mixture of them. If, however, a soul has the capacity for sensation, as animals do, then they also have a nutritive faculty (414b1-2). Likewise, for beings who have minds, they must also have the sensitive and nutritive faculties of soul. A plant has only the nutritive faculty of soul, which is responsible for nourishment and reproduction. Animals have sense perception in varying degrees, and must also have the nutritive faculty, which allows them to survive. Human beings have intellect or mind (nous) in addition to the other faculties of the soul.

The soul is the source and cause of the body in three ways: the source of motion, the telos, and the being or essence of the body (415b9-11). The soul is that from which and ultimately for which the body does what it does, and this includes sensation. Sensation is the ability to receive the form of an object without receiving its matter, much as the wax receives the form of the signet ring without receiving the metal out of which the ring is made. There are three types of sensible things: particular sensibles, or those qualities that can be sensed by one sense only; common sensibles, which can be sensed by some combination of various senses; and incidental sensibles, as when I see my friend Tom, whose father is Joe, I say that I see “the son of Joe,” but I see Joe’s son only incidentally.

Mind (nous), as it was for Anaxagoras, is unmixed (429a19). Just as senses receive, via the sense organ, the form of things, but not the matter, mind receives the intelligible forms of things, without receiving the things themselves. More precisely, mind, which is nothing before it thinks and is therefore itself when active, is isomorphic with what it thinks (429a24). To know something is most properly to know its form, and mind in some way becomes the form of what it thinks. Just how this happens is unclear. Since the form is what is known, the mind “receives” or becomes that form when it best understands it. So, mind is not a thing, but is only the activity of thinking, and is particularly whatever it thinks at any given time.

c. Ethics

The most famous and thorough of Aristotle’s ethical works is his Nicomachean Ethics. This work is an inquiry into the best life for human beings to live. The life of human flourishing or happiness (eudaimonia) is the best life. It is important to note that what we translate as “happiness” is quite different for Aristotle than it is for us. We often consider happiness to be a mood or an emotion, but Aristotle considers it to be an activity—a way of living one’s life. Thus, it is possible for one to have an overall happy life, even if that life has its moments of sadness and pain.

Happiness is the practice of virtue or excellence (arete), and so it is important to know the two types of virtue: character virtue, the discussion of which makes up the bulk of the Ethics, and intellectual virtue. Character excellence comes about through habit—one habituates oneself to character excellence by knowingly practicing virtues. To be clear, it is possible to perform an excellent action accidentally or without knowledge, but doing so would not make for an excellent person, just as accidentally writing in a grammatically correct way does not make for a grammarian (1105a18-26). One must be aware that one is practicing the life of virtue.

Aristotle arrives at the idea that “the activity of the soul in accordance with virtue” is the best life for human beings through the “human function” argument. If, says Aristotle, human beings have a function or work (ergon) to perform, then we can know that performing that function well will result in the best sort of life (1097b23-30). The work or function of an eye is to see and to see well. Just as each part of the body has a function, says Aristotle, so too must the human being as a whole have a function (1097b30). This is an argument by analogy. The function of the human being is logos or reason, and the more thoroughly one lives the life of reason, the happier one’s life will be (1098a3).

So, the happiest life is a practice of virtue, and this is practiced under the guidance of reason. Examples of character virtues would be courage, temperance, liberality, and magnanimity. One must habitually practice these virtues in order to be courageous, temperate, and so forth. For example, the courageous person knows when to be courageous, and acts on that knowledge whenever it is appropriate to do so (1115a16-34). Each activity of any particular character virtue has a related excessive or deficient action (1105a24-33). The excess related to courage, for example, is rashness, and the deficiency is cowardice. Since excellence is rare, most people will tend more towards an excess or deficiency than towards the excellent action. Aristotle’s advice here is to aim for the opposite of one’s typical tendency, and that eventually this will lead one closer to the excellence (1109a29-1109b6). For example, if one tends towards the excess of self-indulgence, it might be best to aim for insensibility, which will eventually lead the agent closer to temperance.

Friendship is also a necessary part of the happy life. There are three types of friendship, none of which is exclusive of the other: a friendship of excellence, a friendship of pleasure, and a friendship of utility (1155b18). A friendship of excellence is based upon virtue, and each friend enjoys and contemplates the excellence of his/her friend. Since the friend is like another self (1166a31), contemplating a friend’s virtue will help us in the practice of virtue for ourselves (1177b10). A mark of good friendship is that friends “live together,” that is that friends spend a substantial amount of time together, since a substantial time apart will likely weaken the bond of friendship (1157b5-11)). Also, since the excellent person has been habituated to a life of excellence, his/her character is generally firm and lasting. Likewise, the friendship of excellence is the least changeable and most lasting form of friendship (1156b18).

The friendships of pleasure and use are the most changeable forms of friendship since the things we find pleasurable or useful tend to change over a lifetime (1156a19-20). For example, if a friendship forms out of a mutual love for beer, but the interest of one of the friends later turns towards wine, the friendship would likely dissolve. Again, if a friend is merely one of utility, then that friendship will likely dissolve when it is no longer useful.

Since the best life is a life of virtue or excellence, and since we are closer to excellence the more thoroughly we fulfill our function, the best life is the life of theoria or contemplation (1177a14-18). This is the most divine life, since one comes closest to the pure activity of thought (1177b30). It is the most self-sufficient life since one can think even when one is alone. What does one contemplate or theorize about? One contemplates one’s knowledge of unchanging things (1177a23-27). Some have criticized Aristotle saying that this sort of life seem uninteresting, since we seem to enjoy the pursuit of knowledge more than just having knowledge. For Aristotle, however, the contemplation of unchanging things is an activity full of wonder. Seeking knowledge might be good, but it is done for the sake of a greater end, namely having knowledge and contemplating what one knows. For example, Aristotle considered the cosmos to be eternal and unchanging. So, one might have knowledge of astronomy, but it is the contemplation of what this knowledge is about that is most wonderful. The Greek word theoria is rooted in a verb for seeing, hence our word “theatre.” So, in contemplation or theorizing, one comes face to face with what one knows.

d. Politics

The end for any individual human being is happiness, but human beings are naturally political animals, and thus belong in the polis, or city-state. Indeed, the inquiry into the good life (ethics) belongs in the province of politics. Since a nation or polis determines what ought to be studied, any practical science, which deals with everyday, practical human affairs, falls under the purview of politics (1094a26-1094b11). The last chapter of Nicomachean Ethics is dedicated to politics. Aristotle emphasizes that the goal of learning about the good life is not knowledge, but to become good (1095a5), and he reiterates this in the final chapter (1179b3-4). Since the practice of virtue is the goal for the individual, then ultimately we must turn our eyes to the arena in which this practice plays out—the polis.

A good individual makes for a good citizen, and a good polis helps to engender good individuals: “Legislators make the citizens good by forming habits in them, and this is the wish of every legislator; and those who do not effect it miss their mark, and it is in this that a good constitution differs from a bad one” (1103b3-6). Laws must be instituted in such a way as to make its citizens good, but the lawmakers must themselves be good in order to do this. Human beings are so naturally political that the relationship between the state and the individual is to some degree reciprocal, but without the state, the individual cannot be good. In the Politics, Aristotle says that a man who is so self-sufficient as to live away from a polis is like a beast or a god (1253a29). That is, such a being is not a human being at all. Again, a man who is separated from law and justice is the “worst of all” (1253a32).

In Book III.7 of the Politics, Aristotle categorizes six different political constitutions, naming three as good and three as bad. The three good constitutions are monarchy (rule by one), aristocracy (rule by the best, aristos), and polity (rule by the many). These are good because each has the common good as its goal. The worst constitutions, which parallel the best, are tyranny, oligarchy, and democracy, with democracy being the best of the three evils. These constitutions are bad because they have private interests in mind rather than the common good or the best interest of everyone. The tyrant has only his own good in mind; the oligarchs, who happen to be rich, have their own interest in mind; and the people (demos), who happen not to be rich, have only their own interest in mind.

Yet, Aristotle grants that there is a difference between an ideal and a practically plausible constitution, which depends upon how people actually are (1288b36-37). The perfect state will be a monarchy or aristocracy since these will be ruled by the truly excellent. Since, however, such a situation is unlikely when we face the reality of our current world, we must look at the next best, and the next best after that, and so on. Aristotle seems to favor democracy, and after that oligarchy, but he spends the bulk of his time explaining that each of these constitutions actually takes many shapes. For example, there are farmer-based democracies, democracies based upon birth status, democracies wherein all free men can participate in government, and so forth (1292b22-1293a12).

The most unfortunate aspect of Aristotle’s politics is his treatment of slavery and women, and we might wonder how it affects his overall inquiry into politics:

The male is by nature superior, and the female inferior; and the one rules, and the other is ruled; this principle, of necessity, extends to all mankind. Where then there is such a difference as that between soul and body, or between men and animals (as in the case of those whose business is to use their body, and who can do nothing better), the lower sort are by nature slaves, and it is better for them as for all inferiors that they should be under the rule of a master. For he who can be, and therefore is, another’s, and he who participates in reason enough to apprehend, but not to have, is a slave by nature. Whereas the lower animals cannot even apprehend reason; they obey their passions. (Politics 1254b13-23)

For Aristotle, women are naturally inferior to men, and there are those who are natural slaves. In both cases, it is a deficiency in reason that is the culprit. Women have reason but “lack authority” (1260a14), and slaves have reason enough to take orders and have some understanding of their world, but cannot use reason as the best human being does. It is difficult, if not impossible, to interpret Aristotle charitably here. For slaves, one might suggest that Aristotle has in mind people who can do only menial tasks, and nothing more. Yet, there is a great danger even here. We cannot always trust the judgment of the master who says that this or that person is capable only of menial tasks, nor can we always know another person well enough to say what the scope of his or her capabilities for thought might be. So even a charitable interpretation of his views of slavery and women is elusive.

e. Physics

Aristotle’s physics, which stood as the most influential study of physics until Newtonian physics, could be seen largely as a study of motion. Motion is defined in the Physics as the “actuality of the potentiality in the very way in which [the thing in motion] is in potentiality” (201b5). Motion is not merely a change of place. It can also include processes of change in quality and quantity (201a4-9). For example, the growth of a plant from rhizome to flower (quantity) is a process of motion, even though the flower does not have any obvious lateral change of place. The change of a light skin-tone to bronze via sun tanning is a qualitative motion. In any case, the thing in motion is not yet what it is becoming, but it is becoming, and is thus actually a potentiality qua potentiality. The light skin is not yet sun tanned, but is becoming sun tanned. This process of becoming is actual, that is that the body is potentially tanned, and is actually in the process of this potentiality. So, motion is the actuality of the potentiality of a being, in the very way that it is a potentiality.

In Book 8.1 of the Physics, Aristotle argues that the cosmos and its heavenly bodies are in perpetual motion and always has been. There could not have been a time with no motion, whatever is moved is moved by itself or by another. Rest is simply a privation of motion. Thus, if there were a time without motion, then whatever existed—which had the power to cause motion in other beings—would have been at rest. If so, then it at some point had to have been in motion since rest is the privation of motion (251a8-25). Motion, then, is eternal. What moves the cosmos? This must be the unmoved mover, or God, but God does not move the cosmos as an efficient cause, but as a final cause. That is, since all natural beings are telic, they must move toward perfection. What is the perfection of the cosmos? It must be eternal, perfectly circular motion. It moves towards divinity. Thus, the unmoved mover causes the cosmos to move toward its own perfection.

f. Metaphysics

Aristotle’s Metaphysics, legendarily known as such because it was literally categorized after (meta) his Physics, was known to him as “first philosophy”—first in status, but last in the order in which we should study his corpus. It is also arguably his most difficult work, which is due to its subject matter. This work explores the question of what being as being is, and seeks knowledge of first causes (aitiai) and principles (archai). First causes and principles are indemonstrable, but all demonstrations proceed from them. They are something like the foundation of a building. The foundation rests upon nothing else, but everything else rests upon it. We can dig to the foundation, but (let’s pretend there’s no further earth under it) we can go no further. Likewise, we can reason our way up (or down) to the first principles and causes, but our reasoning and ability to know ends there. Thus, we are dealing with an inherently difficult and murky subject, but once knowledge of this subject is gained, there is wisdom (Metaphysics 982a5). So, if philosophy is a constant pursuit of wisdom for Plato, Aristotle believed that the attainment of wisdom is possible.

Aristotle says that there are many ways in which something is said to be (Meta.1003b5), and this refers to the categories of being. We can talk about the substance or being (ousia) of a thing (what that thing essentially is), quality (the shirt is red), quantity (there are many people here), action (he is walking), passion (he is laughing), relation (A is to B as B is to C), place (she is in the room), time (it is noon), and so on. We notice in each of these categories that being is at play. Thus, being considered qua being cannot be restricted to any one of the categories but cuts across all of them.

So what is being or substance? The form of a thing makes it intelligible, rather than its matter, since things with relatively the same form can have different matter (metal baseball bats and wooden baseball bats are both baseball bats). Here, we are really getting at the essence of something. Aristotle’s phrase for essence is “to ti en einai,” which could be translated as “what it is (was) to be” this or that thing. Since nothing is what it is outside of matter—there is no form by itself, just as there is no pure matter by itself—the essence of anything, its very being, is its being as a whole. No particular being is identical with its quality, quantity, position in space, or any other incidental features. It is the singular being as a whole, the “this” to which we can apply no further name, that shows us the being in its being.

The Metaphysics then arrives at a similar end as does the Physics, with the first mover. But, in the Metaphysics, we are not primarily concerned with the motion of physical beings but with the being of all beings. This being, God, is pure actuality, with no mixture of any potentiality at all. In short, it is pure being, and is always being itself in completion. Thinking is the purest of activities, according to Aristotle. God is always thinking. In fact, God cannot do otherwise than think. The object of God’s thought is thinking itself. God is literally thought thinking thought (1072b20). We recall from Aristotle’s psychology that mind becomes what it thinks, and Aristotle reiterates this in the Metaphyiscs (1072b20-22). Since God is thinking, and thinking is identical with its object, which is thought, God is the eternal activity of thinking.

5. Hellenistic Thought

The Hellenistic period in philosophy is generally considered to have commenced with Alexander’s death in 323, and ended approximately with the Battle of Actium in 31 BC. Although the Academy and the Lyceum could be considered in a thorough investigation into Hellenistic philosophy, scholars usually focus upon the Epicureans, Cynics, Stoics, and Skeptics.

Hellenistic philosophy is traditionally divided into three fields of study: physics, logic, and ethics. Physics involved a study of nature while logic was broadly enough construed to include not only the rules of what we today consider to be logic but also epistemology and even linguistics.

a. Epicureanism

Epicurus (341-271 B.C.E.) and his school are often mistakenly considered to be purely hedonistic, such that nowadays an “epicure” designates one who delights in fine foods and drinks. Etymologically, it is accurate to call Epicurus and his followers “hedonists,” where we refer merely to pleasure, without restricting that pleasure to bodily pleasures. Epicurus’ school, the Garden (an actual Garden near Athens), was primarily friendly in nature, and non-hierarchical (Dorandi 57). Although Epicurus was a prolific author, we have only three of his letters preserved in Diogenes Laertius’ Lives. Otherwise, we depend in large part upon the Epicurean Lucretius and his work On the Nature of Things, especially in order to understand Epicurean physics, which was essentially materialistic. The goal of all true understanding for Epicurus, which must involve an understanding of physics, was tranquility.

i. Physics

Epicurus and his followers were thoroughgoing materialists. Everything except the void, even the human soul, is composed of material bodies. Epicureans were atomists and accordingly thought that there is nothing but atoms and void. Atoms “vary indefinitely in their shapes; for so many varieties of things as we see could never have arisen out of a recurrence of a definite number of the same shapes” (DL X.42). Moreover, these atoms are always in motion, and will remain in motion in the void until something can offer enough resistance to stop an atom in motion.

Epicurus’ view of atomic motion provides an important point of departure from Democritean atomism. For Democritus, atoms move according to the laws of necessity, but for Epicurus, atoms sometimes swerve, or venture away from their typical course, and this is due to chance. Chance allows room for free will (Lucretius 2.251-262). Epicureans seem to take for granted that there is freedom of the will, and then apply that assumption to their physics. That is, there seems to be free will, so Epicureans then posit a physical explanation for it.

ii. Ethics

Much of what we know about Epicurean ethics comes from Epicurus’ Letter to Menoeceus, which is preserved in Diogenes Laertius’ Lives. The goal of the good life is tranquility (ataraxia). One achieves tranquility by seeking pleasure (hedone), but not just any pleasure will suffice. The primary sort of pleasure is the simplicity of being free from pain and fear, but even here, we should not seek to be free from every sort of pain. We should pursue some painful things if we know that doing so will render greater pleasure in the end (DL X.129-130). So, Epicurus’ hedonism shapes up to be a nuanced hedonism. Indeed, he recommends a plain life, saying that the most enjoyment of luxury comes to those who need luxury least (DL X.130). Once we habituate ourselves to eating plain foods, for example, we gradually eliminate the pain of missing fancy foods, and we can enjoy the simplicity of bread and water (DL X.130-131). Epicurus explicitly denies that sensual pleasures constitute the best life and argues that the life of reason—which includes the removal of erroneous beliefs that cause us pain—will bring us peace and tranquility (DL X.132).

The sorts of beliefs that produce pain and anxiety for us are primarily two: a mistaken conception of the gods, and a misconception of death. Most people, according to Epicurus, have mistaken conceptions about the gods, and are therefore impious (DL X.124). Similar to Xenophanes, Epicurus would encourage us not to anthropomorphize the gods and to think only what is fitting for the most blessed and eternal beings. We are not thinking clearly when we think that the gods get angry with us or care at all about our personal affairs. It is not befitting of an eternal and blessed being to become angry over or involved in the affairs of mortals. Yet, perhaps Epicurus is anthropomorphizing here. The argument seems to rely upon his argument that tranquility is our greatest pleasure and upon the assumption that the gods must experience that pleasure. On the other hand, one could read Epicurus as a sort of proto-negative theologian who merely suggests that it is unreasonable to believe that gods, the best of beings, feel pain at all. One might wonder whether anthropomorphizing is avoidable at all.

We should not fear death because death is “nothing to us, for good and evil imply sentience, and death is the privation of all sentience” (DL X.124). The key here is the first premise that good and evil apply only to sentient beings. We recall that, for Epicurus, we are thoroughly material beings. Both mind and soul are part of the human body, and the human body is nothing if not sentient. Therefore, when the body dies, so too does the mind and soul, and so too does sentience. This means that death is literally nothing to us. The terror that we feel about death now will vanish once we die. Thus, it is better to be free from the fear of death now. When we rid ourselves of the fear of death, and the hope of immortality that accompanies that fear, we can enjoy the preciousness of our mortality (DL X.124-125).

b. The Cynics

The Cynics, unlike the Epicureans, were not properly a philosophical school. While there are identifiable characteristics of cynical thought, they had no central doctrine or tenets. It was a disparate movement, with varying interpretations on what constituted a Cynic. This interpretative freedom accords well with one of the characteristics that typified ancient Cynicism—a radical freedom from societal and cultural standards. The Cynics favored instead a life lived according to nature.

“Cynic,” from the Greek kunikos, meant “dog-like.” We cannot be sure whether the Dogs thought of themselves as doglike, or whether they were termed as such by non-Cynics, or both. The first of the Dogs, Antisthenes (c.445-366 B.C.E.), was supposedly close with Socrates, and was present at his death, according to Plato’s Phaedo. Yet, it was Diogenes of Sinope (c.404-323 B.C.E.), often called simply, “Diogenes the Cynic,” who was and is the most famous of the Dogs. Most information we have comes from Diogenes Laertius’ Lives, which was written centuries after Diogenes the Cynic’s life, and is therefore historically problematic. It nevertheless provides us with an imaginative description of Diogenes the Cynic’s life, which was apparently unusual and outstanding.

Diogenes the Cynic was purportedly exiled from Sinope for defacing the city’s coins, and this later became his metaphorical modus operandi for philosophy—“driving out the counterfeit coin of conventional wisdom to make room for the authentic Cynic life” (Branham and Goulet-Cazé 8). The cynic life referenced here consisted of a life lived in accordance with nature, a rebellion against and freedom from dominant Greek culture that lives contrary to nature, and happiness through askesis, or asceticism (Branham and Goulet-Cazé 9). Thus, Diogenes wore but a thin, rough cloak all year round, accustomed himself to withstand both heat and cold, ate but a meager diet, and most sensationally, openly mocked everyday Greek life.

He was reportedly at a dinner party where the attendants were throwing bones at him as though he were a dog. So, Diogenes “urinated upon them as a dog would” (DL VI.46). He reportedly masturbated in public, and when reprimanded for it, he replied that he “wished it were as easy to relieve hunger by rubbing an empty stomach” (DL VI.46). Again, “He lit a lamp in broad daylight and said, as he went about, ‘I am looking for a human being’” (DL VI.41), implying that none of the Greeks could appropriately be called “human.” These shenanigans were intended to wake up the Athenians to the life of simplicity and philosophy. One needs very little to be happy. In fact, one should severely limit one’s desires, and live as most animals do, without anxiety, and securing only what one needs to continue living. This all seems a response to the cold fact that much of human life and circumstance is out of our control. So, Diogenes claimed that philosophy was a practice that prepared him for any kind of luck (DL VI.63).

The Cynics seem to have taken certain aspects of Socrates’ life and thought and pushed it to the extreme. One might wonder what drives the ascetic practice for any sort of luck. Is it that we see that moving from one superficial pleasure to the next is ultimately unfulfilling? Or, is the practice itself driven by a sort of fear, an emotion that the Cynic means to quell? That is, one might read the asceticism of the Cynic as a futile attempt to deny the truth of human fragility; for example, at any moment the things I enjoy can vanish, so I should avoid enjoying those things. On the other hand, perhaps the asceticism of the Cynic is an affirmation of this fragility. By living the ascetic life of poverty, the Cynic is constantly recognizing and affirming his/her finitude and fragility by choosing never to ignore it.

c. The Stoics

Stoicism evolved from Cynicism, but was more doctrinally focused and organized. While the Cynics largely ignored typical fields of study, the Stoics embraced physics, logic, and ethics, making strides especially in logic. Zeno of Citium (c.334-262 B.C.E.) was the founder of the stoic school, which was named after the Stoa Poikile, a “painted portico” where the Stoics regularly met. This was the beginning of a long and powerful tradition, which lasted into the imperial era. Indeed, one of the most famous of stoic ethicists was the Roman emperor Marcus Aurelius (121-180 C.E.). Epictetus (55-135 C.E.) is another famous Stoic ethicist who also carried on the tradition of Stoicism beyond the Hellenistic period. Although the Stoics made some strides in logic after Aristotle, this article’s focus is on Stoic physics, epistemology, and ethics.

i. Physics

As Pierre Hadot has shown, the Stoics studied physics in order better to understand their own lives, and to live better lives: “Stoic physics was indispensible for ethics because it showed people that there are some things which are not in their power but depend on causes external to them—causes which are linked in a necessary, rational manner” (Hadot 128). Like the Cynics, the Stoics strove to live in accordance with nature, and so a rigorous study of nature allowed them to do so all the more effectively.

The Stoics were materialists, though not thoroughgoing materialists as the Epicureans were. Also, chance can play no role in the Stoics’ ordered and thoroughly rational and causally determined universe. Since we are part of this universe, our lives, too, are causally determined, and everything in the universe is teleologically oriented towards its rational fulfillment. Diogenes Laertius reports that the Stoics saw matter as passive and logos (god) as active, and that god runs through all of the matter as its organizing principle (DL VII.134). This divinity is most apparent in us via our ability to reason. At any rate, the universe is, as the name implies, a unity, and it is divine.

ii. Epistemology

The knowledge we have of the world comes to us directly through our senses and impresses itself upon the blank slate of our minds. The naked information that comes to us via the senses allows us to know objects, but our judgments of those objects can lead us into error. As Hadot says about these so-called objective presentations, “They do not depend on our will; rather, our inner discourse enunciates and describes their content, and we either give or withhold our consent from this enunciation” (Hadot 131). There might be a problem lurking here regarding the standard of truth, which, for the Stoics, is simply the correspondence of one’s idea of the object with the object itself. If it is true that the correspondence of our descriptions of the object with the actual object can bring us knowledge, how can we ever be sure that our descriptions really match the object? After all, if it is not the bare sense impression that brings knowledge, but my correct description of the object, it seems that there is no standard by which I can ever be sure that my description is correct.

iii. Ethics

Stoic ethics urges us to be rid of our desires and aversions, especially where these desires and aversions are not in accord with nature. For instance, death is natural. To be averse to death will bring misery. Stoic ethics can perhaps be best summed up in the first paragraph of Epictetus’ Handbook:

Some things are up to us and some are not up to us. Our opinions, and our impulses, desires, aversions—in short, whatever is our own doing. Our bodies are not up to us, nor are our possessions, our reputations, or our public offices, or, that is, whatever is not our own doing. The things that are up to us are by nature free, unhindered, and unimpeded; the things that are not up to us are weak, enslaved, hindered, not our own…If you think that only what is yours is yours, and that what is not your own is…not your own, then no one will ever coerce you, no one will hinder you, you will blame no one, you will have no enemies, and no one will harm you, because you will not be harmed at all.

This passage might be shocking to us today when, especially in the United States, many of the things that Epictetus tells us to avoid are what we are told to pursue. We therefore might wonder why our bodies, possessions, reputations, wealth, or jobs are not in our control. For Epictetus, it is simple. Possessions come and go—they can be destroyed, lost, stolen, and so forth. Reputations are determined by others, and it is reasonable to believe that even the best people will be hated by some, and even the worst people will be loved by some. Try as we might, we might never gain wealth, and even if we do, it can be lost, destroyed, or stolen. Again, public office, like reputation, is up to others to determine. So, the adage that “you can be anything you want in life” is not only false under stoic ethics, but dangerously misleading since it will almost inevitably lead to misery.

Just because, however, I live as Epictetus recommends, how can I be sure that I will never be harmed? Even if I fully grant that someone who, for instance, pushes me down a flight of stairs has committed his own wrong, and that his wrong actions are not in my control, will I not still feel pain? Physical pain, for a Stoic, is not harm. The only real harm is when one harms oneself by doing evil, just as the only real good is living excellently and in accordance with reason. In this example, I would harm myself with the judgment that what happened to me was bad. One might object here, as one might object to Cynicism, that stoic ethics ultimately demands a repression of what is most human about us. Indeed, Epictetus says, “If you kiss your child or wife, say that you are kissing a human being; for when it dies you will not be upset” (Handbook 12). For the Stoic, being moved by others brings us away from tranquility. However, kissing a “human being” is not the same as kissing this human being, this individual who would be deeply hurt by knowing that I treat them merely as a human being, and who I relate to only through a sense of duty, rather than a real sense of love. Stoic ethics risks removing our humanity from us in favor of its own notion of divinity.

d. Skeptics

The two strands of Skepticism in the Hellenistic era were Academic Skepticism and Pyrrhonian Skepticism. Somewhat like the Cynics, each major Skeptic had his own take on Skepticism, and so it is difficult to lump them all under a tidy label. Also like the Cynics, however, there are certain characteristics that can be highlighted, despite differences between particular thinkers. Skepsis means “inquiry,” but the Skeptics did not seek solid or absolute answers as the goal of their inquiry. Rather, the goal of their skepsis was tranquility and freedom from judgments, opinions, or absolute claims to knowledge. Skepticism, broadly speaking, constituted a challenge to the possibility and nature of knowledge.

i. Academic Skepticism

The sixth scholarch (leader) of Plato’s Academy was Arcesilaus (318-243 B.C.E.), who initiated a substantial tradition of Skepticism in the Academy that lasted into the first century B.C.E. Arcesilaus found the inspiration for his skepticism in the figure of Socrates. Arcesilaus would argue both for and against any given position, ultimately showing that neither side of the argument can be trusted. He directed his skepticism primarily toward the Stoics and the empirical basis of their claims to knowledge. We recall that, for the Stoics, a grasping of sense impressions in the proper way is the true foundation for knowledge. Arcesilaus’ argument against stoic empiricism is not clear (the argument is recounted in Cicero’s Academia 2.40-42), but it seems ultimately to reach the conclusion suggested above, namely that we can never be sure that the way we have perceived (judged) an object via the senses is true or false. The argument runs roughly as follows. For any given presentation of an object to the senses, we can imagine that something else could be presented to the senses in just the same way, such that the perceiver cannot distinguish between the two objects being presented, which Arcesilaus thought the Stoics would grant. The perceiver can present these objects to him/herself, via the senses, in a true or false way, which the Stoics would also grant. It is possible, then, that the perceiver thinks one presentation is true and the other is false, but he has no way of distinguishing between either. Arcesilaus’ conclusion is that we should always suspend our judgment.

Carneades (213-129 B.C.E.), the tenth scholarch of Plato’s Academy, seems to have cleverly answered a typical objection raised against Skepticism. It is inconsistent, goes the objection, to insist that it is impossible for anything to be known (“grasped”), since that statement, “nothing can be known” is itself a claim to knowledge. Carneades recognized that even the claim “nothing can be known” should be called into doubt. Again, like Arcesilaus, Carneades relied upon the typical skeptic tactic of presenting arguments both for and against the same thing and claiming that we cannot therefore claim that either side is correct.

ii. Pyrrhonian Skepticism

We know almost nothing for sure about Pyrrho of Elis (360-270 B.C.E.). He wrote nothing, which is perhaps a sign of his extreme skepticism, that is if we cannot know anything, or cannot be sure whether knowledge is possible, then nothing can definitively be said, especially in writing. Perhaps what most differentiates Pyrrhonian Skepticism from Academic Skepticism is the profound indifference that Pyrrhonian Skepticism is meant to generate. Diogenes Laertius relays the story that, when his master Anaxarchus had fallen into a swamp, Pyrrho simply passed him by, and was later praised by Anaxarchus for his supreme indifference (DL IX.63). Pyrrhonian Skepticism refutes all dogmas and opinions and vehemently clings to indeterminacy, even the idea that “nothing can be known.”

Aenesidemus, the Pyrrhonian Skeptic, advanced the “Ten Modes,” arguments that address typical difficulties in appearances and judgment—each aimed toward the conclusion that we ought to suspend judgment if we are to be at peace. The first mode argues that other animals sense things differently from human beings, and that we cannot therefore pretend to place any absolute value on the things sensed. Since the qualities of sensation vary from species to species, for example “the quail thrives on hemlock, which is fatal to man” (DL IX.80) we ought to suspend value judgments upon those things. In the quoted example, then, the hemlock is clearly not in itself evil, but neither is it in itself good, but it is a matter of indifference. The remaining modes follow a similar pattern, highlighting relativity—whether cultural, personal, sensory, qualitative or quantitative—as evidence that we ought to suspend judgment.

The Skeptics, as Pierre Hadot says, use “philosophical discourse…to eliminate philosophical discourse” (143). That is, they do not adhere to any philosophical position, but use the tools of philosophy to gain a sense of simplicity and tranquility in life, thereby ridding themselves of the need for philosophy. By using dialectic, and opposing one argument to another, the Skeptic suspends judgment, and is not committed to any particular position. The Skeptic,

In everything he did…was to limit himself to describing what he experienced, without adding anything about what things are or what they are worth. He was to be content to describe the sensory representations he had, and to enunciate the state of his sensory apparatus, without adding to it his opinion. (Hadot 145)

We might wonder just how practical such an approach to life would be. Can we flourish or thrive, effectively communicate, or find cures for diseases by merely describing our experience of the world? For example, antibiotics can help, more often than not, to cure diseases born from certain bacteria. Could we not say, for practical purposes, that we know this to be the case? We are not, after all, ignorant of the fact that bacteria are becoming resistant to certain antibiotics, but this does not mean that they do not work, or that we cannot someday find alternative cures for bacterial infections.

The Skeptic could reply in several ways, but the most effective reply to the example provided might go something like this: Medicine does not bring us knowledge, if knowledge is certainty. Medicine, and what it claims to know has, after all, changed significantly. The practice of medicine is just another way of describing the way certain bodies interact with other bodies in a given time and place. But the Skeptic would go further. The curing of a disease, he would say, is neither good nor bad. Perhaps my disease is cured, and the next day, I am killed in some other way. If death is a matter of indifference, then the cure for illnesses must be, too. Again, we might wonder in this case how one is ever spurred to action.

6. Post-Hellenistic Thought

Platonic thought was the dominant philosophical force in the time period following Hellenistic thought proper. This article focuses on the reception and reinterpretations of Plato’s thought in Neoplatonism and particularly in its founder, Plotinus.

a. Plotinus

Plotinus (204-270 C.E.), in his Enneads—a collection of six books broken into sections of nine—builds upon Plato’s metaphysical thought, and primarily upon his concept of the Good. Plotinus is also informed by Aristotle’s work, the Unmoved Mover (thought thinking thought) in particular, and is privy to the bulk of the ancient philosophical tradition. As Kevin Corrigan says, “Plotinus transforms everything he inherits by the very activity of thinking through that inheritance critically and creatively” (23). In other words, Plotinus inherits concepts of unity, the forms, divine intellect, and soul, but makes these concepts his own. The result is a philosophy that comes close to a religious spiritual practice.

There are three aspects to Plotinus’ metaphysics: the One, Intellect, and Soul. The One is the ineffable center of all reality and the wellspring of all that is—more precisely, it is the condition of the possibility for all being, but is itself beyond all being. The One cannot be accurately accounted for in discourse. We can only contemplate it, and at most relay our own experience of this contemplation (Corrigan 26). We can speak negatively about the One (VI, 9.3). Thus, for example, we say that it is impassive. It does not create Intellect or Soul or anything else; rather, by its supreme nature, it merely emanates Intellect and Soul.

i. Intellect, Soul, and Matter

The Intellect emanates from the One because of the One’s fullness. The One, by being the One, simply gives off the Intellect, so to speak (Enneads V, 2.7-18). Since being moves out from its source and returns to its source (Corrigan 28), the Intellect turns towards the One and contemplates it. The Intellect is other than the One, but united with it in contemplation. As other, it gives rise to multiplicity, namely the forms that it is and that it thinks (it thus thinks itself). The Intellect generates Soul, which shares in intellect, but also animates the material world. Thus, the material world is generated by Soul, and this includes every individual being. A particular human being, then, has its share of soul, and its highest part of the soul is intellect, where true selfhood is.

ii. The True Self and the Good Life

The best life for human beings necessitates that each human become his or her own true self, which is the intellect. That is, we must turn away, as much as is possible, from matter and the sensible world, which are distractions, and be intellect (Enneads I.4). To become one’s true self is to live the best life. Being oneself in this sense, however, is quite different from the individuality promoted in the Western world. Hadot says, “To become a determinate individual is to separate oneself from the All by adding a difference which, as Plotinus says, is a negation. By cutting off all individual differences, and therefore our own individuality, we can become the All once again” (166). The best life depends upon becoming one’s true self via the intellect, which means to step away from the part of the soul by which we typically identify ourselves, the passionate and desiring part of the soul. If we are now accustomed to identify ourselves by our likes, dislikes, opinions, , then a true Plotinian self would not be a self at all. For Plotinus, however, this is true selfhood since it is closest to the center of all life, the One.

b. Later Neoplatonists

Plotinus set off a tradition of thought that had great influence in medieval philosophy. This tradition has been known since the 19th century as “Neoplatonism,” but Plotinus and other Neoplatonists saw themselves merely as followers and interpreters of Plato (Dillon and Gerson xiii). Plotinus’ student, Porphyry, without whom we would know little to nothing about Plotinus or his work, carried on the tradition of his master, although we do not possess a full representation of his work. With Iamblichus came a focus upon Aristotle’s work, since he took Aristotle as an informative source on Platonism. Neoplatonism also saw the rise of Christianity, and therefore saw itself to some degree in a confrontation with it (Dillon and Gerson xix). Perhaps in part because of this confrontation with Christianity, later Neoplatonists aimed to develop the religious aspects of Neoplatonic thought. Thus, the later Neoplatonists introduced theurgy, claiming that thought alone cannot unite us with gods, but that symbols and rites are needed for such a union (Hadot 170-171).

c. Cicero and Roman Philosophy

Greek philosophy was the dominant philosophy for years, including in the Roman Republic and in the imperial era. Cicero (106-43 B.C.E.) considered himself to be an Academic Skeptic, although he did not take his skepticism as far as a renunciation of politics and ethics. He is a very useful source for the preservation of and commentary upon not only Academic Skepticism, but also the Peripatetics, Stoics, and Skeptics. He was also an accomplished orator and politician, and authored many works of his own, which often employed skeptic principles or commented upon other philosophies. He took pains, as a true Skeptic, to present both sides of an argument. Cicero was murdered during the rise of the Roman empire.

Stoicism played an important role in the imperial period, especially with the Roman emperor Marcus Aurelius. Marcus is most famous for his so-called Meditations, which is a translation of the Greek ta eis heauton, “[things] to himself.” As the Greek title clearly shows, these meditations were meant for Marcus himself. These were reminders on how to live, especially as an emperor who saw turbulent times. This work, in its usually short, pithy statements, reveals some principles of stoic physics, but this only in service of its larger ethical orientation. It advocates a life of simplicity and tranquility lived according to nature.

7. Conclusion

From the Presocratics to the Hellenists, there is a preference for reason, whether it is used to find truth or tranquility. The Presocratics prefer reason or reasoned accounts to mythology, sometimes in order to find physical explanations for the phenomena all around us, to think more clearly about the gods, or sometimes to find out truths about our own psychology. For Socrates, the exercise of reason and argumentation was important to recognize one’s own limitations as a human being. For Plato, the life of reason is the best life, even if it cannot ultimately answer every question. Aristotle used reason to investigate the world around him, in some sense resuscitating the Presocratic preference for physical explanations, and returning lofty discussions to earth. The Hellenists emphasized philosophical practice, always in accordance with reason. We have also seen the profoundly influential tradition set in motion by Plato with the development of his thought into the so-called Neoplatonic era. That scholars and the intellectually curious alike still read these works, and not merely for historical purposes, is a testament to the depth of thought contained therein.

8. References and Further Reading

a. Presocratics

i. Primary Sources

Diels, Hermann and Walther Kranz. Die Fragmente der Vorsokratiker: Griechisch und Duetsch. Berlin: Weidmannsche Buchhandlung, 1910. Print.
- This is the first and most traditionally used collection of Presocratic fragments and testimonies. This edition has the fragments in Greek with German translations. The book is no longer in print, and while it is often still cited in most scholarship, it is not the work cited in this article.
Graham, Daniel W. The Texts of Early Greek Philosophy: The Complete Fragments and Selected Testimonies of the Major Presocratics. 2 vols. Cambridge: Cambridge University Press, 2010.
- This is the first collection of the Presocratic fragments and testimonies published with the original Greek and English translations. It is the work cited in this text. Graham offers a short commentary on the fragments, as well as references for further reading for each thinker. He has organized by topic the fragments for each thinker, and labels the fragments with an F, followed by the number of the fragment. That is how the fragments have been cited in this article. Testimonies are cited merely by their designated numbers.

ii. Secondary Sources

Barnes, Jonathan. The Presocratic Philosophers. London and New York: Routledge, 1982.
- A classic work with interpretations of the Presocratics.
Burnet, John. Early Greek Philosophy. London: A&C. Black Ltd., 1930.
- Another classic work with interpretations of the Presocratics.
Long, A.A. ed. The Cambridge Companion to Early Greek Philosophy. Cambridge: Cambridge University Press, 1999.
- A collection of sixteen essays by some of the foremost scholars on Presocratic thought. The essays are generally accessible, but some are more appropriate for specialists in the field.
McKirahan, Richard D. Philosophy Before Socrates: An Introduction with Texts and Commentaries. Indianapolis: Hackett, 1994
- This is a book for non-specialists and specialists. It contains most fragments for most thinkers and reasonable explanations and interepretations of each. There is also a helpful chapter at the end of the book on the nomos-phusis debate. The text includes a fairly extensive section for suggestions for further reading.
Vlastos, Gregory. “Ethics and Physics in Democritus.” Philosophical Review, vol. 2, 578-592, 1994.
- This article is technical but offers insight into the connection between Democritean physics and ethics, and it was cited in the current overview.

b. Socrates and Plato

i. Primary Sources

Cooper, John, ed. Plato: Complete Works. Indianapolis: Hackett, 1997.
- The work is the most comprehensive and is also used throughout this article. This collection includes all of Plato’s authentic work as well as every work considered to be spurious or likely spurious. There is no other such collection in English. Any citations of John Cooper in this article come from Cooper’s introduction to this work.
Xenophon, IV: Memorabilia, Oeconomicus, Symposium, and Apology. Jeffrey Henderson ed. E.C. Marchant and O.J. Todd trans. Cambridge: Harvard University Press, 2002.
- This is from the Loeb Classical Library, and accordingly has the original Greek with English on the facing page.

ii. Secondary Sources

Benson, Hugh H., A Companion to Plato. Malden: Blackwell Publishing, 2006.
- This is a collection of scholarly articles on Plato’s work, and on Plato’s version of Socrates.
Brickhouse, Thomas C. and Nicholas D. Smith, Plato’s Socrates. New York: Oxford University Press, 1994.
- This is a scholarly yet approachable book on just what the title suggests. It covers a range of problems that thoughtful readers will encounter when reading Plato.
Kraut, Richard ed. The Cambridge Companion to Plato. Cambridge: Cambridge University Press, 1992.
- This is a collection of articles from premier Plato scholars on a variety of topics.
Morrison, Donald R. ed. The Cambridge Companion to Socrates. Cambridge: Cambridge University Press, 2011.
- This is a collection of scholarship on historical, fictional, and philosophical perspectives of Socrates from Aristophanes to Plato.
Nails, Debra, “The Life of Plato of Athens,” in A Companion to Plato. Hugh H. Benson ed. Malden: Blackwell Publishing, 2006.
Nails, Debra, The People of Plato: a prosopography of Plato and other Socratics. Indianapolis: Hackett, 2002.
- While this book can be laden with details, it is an indispensible resource for Plato scholars, as well as for anyone curious enough to know more about the various interlocutors and character references in Plato’s dialogues.
Taylor, A.E., Plato: The Man and His Work. New York: Meridian Books, 1960.
- Although dated, this book offers of a survey and assessment of the bulk of Plato’s dialogues.
Tigerstedt, E.N., Interpreting Plato. Stockholm: Almqvist & Wiksell International, 1977.
- This book is heavy on detail, but it provides a valuable survey of problems in and interpretations of Plato.
Vlastos, G., Socrates: Ironist and Moral Philosopher. Ithaca: Cornell University Press, 1991.
- This book was especially influential for its chronological categorization of Plato’s dialogues, although the chronological reading has since lost its influence.

c. Aristotle

i. Primary Sources

Barnes, Jonathan ed. The Complete Works of Aristotle. Princeton: Princeton University Press, 1984.
- This book is the most comprehensive, and it includes spurious works or works thought to be spurious. It is also the edition cited in this article.

ii. Secondary Sources

Barnes, Jonathan, The Cambridge Companion to Aristotle. Cambridge; New York: Cambridge University Press, 1995.
- This book contains scholarly articles on a variety of subjects in Aristotle’s thought.
Broadie, Sarah, Ethics With Aristotle. New York ; Oxford: Oxford University Press, 1991
- This book is a good overview of and commentary upon Aristotelian ethics.
Burnyeat, Miles, Map of Metaphysics Zeta. Pittsburgh: Mathesis Publications, 2001.
- This book is meant to help readers navigate one of the most difficult books of Aristotle’s most difficult work.
Irwin, Terence, Aristotle’s First Principles. Oxford: Oxford University Press, 1988.
- Although somewhat dense, this work provides insight into Aristotle’s metaphysical first principles, which underlie much of his work.

d. Hellenistic Philosophy

i. Primary Sources

Empiricus, Sextus, Outlines of Scepticism. Julia Annas and Jonathan Barnes eds. Cambridge: Cambridge University Press, 2000.
- This book gives a good overview of Hellenistic Skepticism, and contains helpful notes from Annas and Barnes.
Epictetus, The Handbook, Nicholas P. White trans. Indianapolis: Hackett, 1983.
- Although Epictetus was not a Hellenist, his formulation of stoic ethics is concise and highly influential. This work was also cited in this article.
Corrigan, Kevin, Reading Plotinus: A Practical Introduction to Neoplatonism. West Lafayette: Purdue University Press, 2005.
- Corrigan presents key readings representative of Plotinus’ philosophy, and after each section of primary readings, provides his own lucid and helpful commentary.
Dillon, John and Lloyd P. Gerson, Neoplatonic Philosophy. Indianapolis: Hackett, 2004.
- This is a helpful introduction to Neoplatonic thought. The bulk of the text are selections of Plotinus’ work, but it also contains selections from Porphyry, Iamblichus, and Proclus.
Inwood, Brad, and L.P. Gerson trans. and ed. Hellenistic Philosophy: Introductory Readings. Indianapolis: Hackett, 1988.
- Since, like the Presocratics, original works are lacking in Hellenistic thought, this book is a good place to begin. It collects central texts, including ancient commentaries, covering the central themes of physics, logic, and ethics from epicurean, stoic, and skeptic perspectives.
Inwood, Brad, and L.P. Gerson trans. and ed. The Stoics Reader: Selected Writings and Testimonia. Indianapolis: Hackett, 2008.
- Again, few original works survive from Hellenistic Stoicism proper, but this book provides central readings in Hellenistic Stoicism.
Laertius, Diogenes, Lives of Eminent Philosophers II. Jeffrey Henderson ed. R.D. Hicks trans.
Cambridge: Harvard University Press, 1931.
- This volume of Diogenes’ famous work contains the three letters purported to be Epicurus’ letters on physics and ethics.
Plotinus, Enneads. 7 vols. ed. Jeffrey Henderson and trans. A.H. Armstrong. Cambridge: Harvard University Press, 1966.
- This is the Loeb edition of Plotinus complete Enneads, along with Porphyry’s “Life of Plotinus.” This edition has the Greek facing the English translation.

ii. Secondary Sources

Algra, Keimpe, Jonathan Barnes, Jaap Mansfeld, and Malcolm Schofield, eds. The Cambridge History of Hellenistic Philosophy. Cambridge: Cambridge University Press, 1999.
- Although this work is intended for specialists and non-specialists alike, it is dense and sometimes overburdened with details for the non-specialists tastes. It does, however, provide valuable historical information and commentary.
Branham, R. Bracht and Marie-Odile Goulet Cazé, The Cynics: The Cynic Movement in Antiquity and Its Legacy. Berkeley: University of California Press, 1996.
- This is an informative collection of scholarly articles on a variety of topics in Cynicism. It also has a very helpful historically oriented introduction, which was cited in this article.
Hadot, Pierre, What is Ancient Philosophy? Michael Chase trans. Cambridge: Harvard University Press, 2002.
- This book contains informative and innovative readings of ancient philosophy in general, and was cited in this article for its treatment of Hellenistic philosophy.

Author Information

Jacob N. Graham
Email: jgraham@bridgewater.edu
Bridgewater College
U. S. A.

Ancient Greek Philosophy

Table of Contents

1. Presocratic Thought

a. The Milesians

b. Xenophanes of Colophon

c. Pythagoras and Pythagoreanism

d. Heraclitus

e. Parmenides and Zeno

f. Anaxagoras

g. Democritus and Atomism

h. The Sophists

2. Socrates

3. Plato

a. Background of Plato’s Work

b. Metaphysics

c. Epistemology

d. Psychology

e. Ethics and Politics

4. Aristotle

a. Terminology

b. Psychology

c. Ethics

d. Politics

e. Physics

f. Metaphysics

5. Hellenistic Thought

a. Epicureanism

i. Physics

ii. Ethics

b. The Cynics

c. The Stoics

i. Physics

ii. Epistemology

iii. Ethics

d. Skeptics

i. Academic Skepticism

ii. Pyrrhonian Skepticism

6. Post-Hellenistic Thought

a. Plotinus

i. Intellect, Soul, and Matter

ii. The True Self and the Good Life

b. Later Neoplatonists

c. Cicero and Roman Philosophy

7. Conclusion

8. References and Further Reading

a. Presocratics

i. Primary Sources

ii. Secondary Sources

b. Socrates and Plato

i. Primary Sources

ii. Secondary Sources

c. Aristotle

i. Primary Sources

ii. Secondary Sources

d. Hellenistic Philosophy

i. Primary Sources

ii. Secondary Sources

Author Information

An encyclopedia of philosophy articles written by professional philosophers.