War is an organized, armed, and often a prolonged conflict that is carried on between states, nations, or other parties typified by extreme aggression, social disruption, and usually high mortality. War should be understood as an actual, intentional and widespread armed conflict between political communities, and therefore is defined as a form of political violence. The set of techniques used by a group to carry out war is known as warfare. An absence of war (and other violence) is usually called peace.

In 2003, Nobel Laureate Richard E. Smalley identified war as the sixth (of ten) biggest problems facing the society of mankind for the next fifty years. In the 1832 treatise On War, Prussian military general and theoretician Carl von Clausewitz defined war as follows: "War is thus an act of force to compel our enemy to do our will."

While some scholars see warfare as an inescapable and integral aspect of human culture, others argue that it is only inevitable under certain socio-cultural or ecological circumstances. Some scholars argue that the practice of war is not linked to any single type of political organization or society. Rather, as discussed by John Keegan in his History of Warfare, war is a universal phenomenon whose form and scope is defined by the society that wages it. Another argument suggests that since there are human societies in which warfare does not exist, humans may not be naturally disposed for warfare, which emerges under particular circumstances. The ever changing technologies and potentials of war extend along a historical continuum. At the one end lies the endemic warfare of the Paleolithic^{[citation needed]} with its stones and clubs, and the naturally limited loss of life associated with the use of such weapons. Found at the other end of this continuum is nuclear warfare, along with the recently developed possible outcome of its use, namely the potential risk of the complete extinction of the human species.

Insanity, craziness or madness is a spectrum of behaviors characterized by certain abnormal mental or behavioral patterns. Insanity may manifest as violations of societal norms, including a person becoming a danger to themselves or others, though not all such acts are considered insanity. In modern usage insanity is most commonly encountered as an informal unscientific term denoting mental instability, or in the narrow legal context of the insanity defense. In the medical profession the term is now avoided in favor of diagnoses of specific mental disorders; the presence of delusions or hallucinations is broadly referred to as psychosis. When discussing mental illness in general terms, "psychopathology" is considered a preferred descriptor.

In English, the word "sane" derives from the Latin adjective sanus meaning "healthy". The phrase "mens sana in corpore sano" is often translated to mean a "healthy mind in a healthy body". From this perspective, insanity can be considered as poor health of the mind, not necessarily of the brain as an organ (although that can affect mental health), but rather refers to defective function of mental processes such as reasoning. Another Latin phrase related to our current concept of sanity is "compos mentis" (lit. "of composed mind"), and a euphemistic term for insanity is "non compos mentis". In law, mens rea means having had criminal intent, or a guilty mind, when the act (actus reus) was committed.

Faith is confidence or trust in a person or entity. Depending on the religion, faith is belief in a single god or multiple gods or in the doctrines or teachings of the religion. Informal usage of faith can be quite broad, including trust or belief without proof, and "faith" is often used as a substitute for "hope", "trust" or "belief".

Some critics of faith have argued that faith is opposed to reason. In contrast, some advocates of faith argue that the proper domain of faith concerns questions which cannot be settled by evidence. This is exemplified by attitudes about the future, which (by definition) has not yet occurred. Logical reasoning may proceed from any set of assumptions, positive or negative. In this view, faith is simply the selection of a positive assumption.

The English word is thought to date from 1200–50, from the Middle English feith, via Anglo-French fed, Old French feid, feit from Latin fidem, accusative of fidēs (trust), akin to fīdere (to trust).

There is a wide spectrum of opinion with respect to the epistemological validity of faith. On one extreme is logical positivism, which denies the validity of any beliefs held by faith; on the other extreme is fideism, which holds that true belief can only arise from faith, because reason and physical evidence cannot lead to truth. Some foundationalists, such as St. Augustine of Hippo and Alvin Plantinga, hold that all of our beliefs rest ultimately on beliefs accepted by faith. Others, such as C.S. Lewis, hold that faith is merely the virtue by which we hold to our reasoned ideas, despite moods to the contrary.