The Athenian philosopher Plato lived in the fifth and fourth centuries BC. His influence on subsequent thought was so great that AN Whitehead once described the whole Western philosophical tradition as “a series of footnotes to Plato.”

As an aristocrat, Plato would have been destined for a political career, but he instead pursued an interest in philosophy. He was a student of Socrates, and his dialogues are the only record of Socratic philosophy of any value. Plato subsequently taught at the Academy, which was at that time attended by Aristotle, the only philosopher of that period to rival Plato in importance.

Central to Plato’s thought is the theory of forms, which holds that there exists a realm of forms, perfect ideals of which things in this world are but imperfect copies. The world that we see around us, according to this theory, is but a pale shadow of the ultimate reality. Things may appear beautiful, or just, insofar as they imitate the forms Beauty and Justice, but the imperfect and changeable world cannot capture the glory of the eternal and immutable forms.

Plato’s contribution to philosophy includes ideas relevant to the philosophy of religion. In Plato’s Laws is the earliest surviving fully developed cosmological argument, though it is not an argument for a single First Cause but rather for at least two, one accounting for good and the other accounting for evil. An early form of the teleological argument can also be found in his works. The Euthyphro dialogue also contains a discussion of the relationship between God and morality, and is often cited as the source of the Euthyphro dilemma, an argument against divine command theory.

Plato also argued for our immortality, suggesting that we know certain things that we cannot possibly have learned in this life, and that we must therefore be remembering things that we knew previously.