Italy over the ages has had a vast influence on Western philosophy, beginning with the Greeks and Romans, and going onto Renaissance humanism, the Age of Enlightenment and modern philosophy.

There were several formidable Roman philosophers, such as Cicero (106–43 BC), Lucretius (94–55 BC), Seneca (4 BC – 65 AD), Musonius Rufus (30 AD – 100 AD), Plutarch (45–120 AD), Epictetus (55–135 AD), Marcus Aurelius (121–180 AD), Clement of Alexandria (150–215 AD), Alcinous (philosopher) (2nd century AD), Sextus Empiricus (3rd century AD), Alexander of Aphrodisias (3rd century AD), Ammonius Saccas (3rd century AD), Plotinus (205–270 AD), Porphyry (232–304 AD), Iamblichus (242–327 AD), Themistius (317–388 AD), Augustine of Hippo (354–430 AD), Proclus (411–485 AD), Philoponus of Alexandria (490–570 AD), Damascius (462–540 AD), Boethius (472–524 AD), and Simplicius of Cilicia (490–560 AD). Roman philosophy was heavily influenced by that of Greece.

Italian Medieval philosophy was mainly Christian, and included several important philosophers and theologians such as St Thomas Aquinas. Aquinas was the student of Albert the Great, a brilliant Dominican experimentalist, much like the Franciscan, Roger Bacon of Oxford in the 13th century. Aquinas reintroduced Aristotelian philosophy to Christianity. He believed that there was no contradiction between faith and secular reason. He believed that Aristotle had achieved the pinnacle in the human striving for truth and thus adopted Aristotle's philosophy as a framework in constructing his theological and philosophical outlook. He was a professor at the prestigious University of Paris.

Giordano Bruno (1548 – February 17, 1600), (Latin: Iordanus Brunus Nolanus) born Filippo Bruno, was an Italian Dominican friar, philosopher, mathematician and astronomer. His cosmological theories went beyond the Copernican model in proposing that the Sun was essentially a star, and moreover, that the universe contained an infinite number of inhabited worlds populated by other intelligent beings. He was burned at the stake by civil authorities in 1600 after the Roman Inquisition found him guilty of heresy for his pantheism and turned him over to the state, which at that time considered heresy illegal. After his death he gained considerable fame, particularly among 19th- and early 20th-century commentators who, focusing on his astronomical beliefs, regarded him as a martyr for free thought and modern scientific ideas.

Some assessments suggest that Bruno's ideas about the universe played a smaller role in his trial than his pantheist beliefs, which differed from the interpretations and scope of God held by the Catholic Church. In addition to his cosmological writings, Bruno also wrote extensively on the art of memory, a loosely organized group of mnemonic techniques and principles. The work of Frances Yates, especially influential in anglophone scholarship, argues that Bruno was deeply influenced by the astronomy found in Arab astrology, Neoplatonism and Renaissance Hermeticism. Other recent studies of Bruno have focused on his qualitative approach to mathematics and his application of the spatial paradigms of geometry to language.

Bertrand Arthur William Russell, 3rd Earl Russell, OM, FRS (18 May 1872 – 2 February 1970) was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he considered himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these in any profound sense. He was born in Monmouthshire, into one of the most prominent aristocratic families in Britain.

Russell led the British "revolt against idealism" in the early 20th century. He is considered one of the founders of analytic philosophy along with his predecessor Gottlob Frege and his friend Ludwig Wittgenstein, and is widely held to be one of the 20th century's premier logicians. He co-authored, with A. N. Whitehead, Principia Mathematica, an attempt to ground mathematics on logic. His philosophical essay "On Denoting" has been considered a "paradigm of philosophy." His work has had a considerable influence on logic, mathematics, set theory, linguistics, computer science (see type theory and type system), and philosophy, especially philosophy of language, epistemology, and metaphysics.