Classical Greek Philosophy

Learning Objective

  • Understand the main philosophical beliefs of Socrates, Plato, and Aristotle

Key Points

  • Socrates is best known for having pursued a probing question-and-answer style of examination on a number of topics, usually attempting to arrive at a defensible and attractive definition of a virtue.
  • In 399 BCE, Socrates was charged for his philosophical inquiries, convicted, and sentenced to death.
  • Plato was a student of Socrates, and is the author of numerous dialogues and letters, as well as one of the primary sources available to modern scholars on Socrates’ life.
  • In his defining work, The Republic, Plato reaches the conclusion that a utopian city is likely impossible because philosophers would refuse to rule and the people would refuse to compel them to do so.
  • Aristotle was a student of Plato, the tutor of Alexander the Great, and founder of the Lyceum and Peripatetic School of philosophy in Athens. He wrote on a number of subjects, including logic, physics, metaphysics, ethics, rhetoric, politics, and botany.


allegory of the cave

A paradoxical analogy wherein Socrates argues that the invisible world is the most intelligible, and the visible world is the least knowable and obscure. Plato has Socrates describe a gathering of people who have lived chained to the wall of a cave all of their lives, facing a blank wall upon which shadows are projected. The shadows are as close as the prisoners get to viewing reality.


The student of Plato, tutor to Alexander the Great, and founder of the Lyceum. A Greek philosopher who wrote on a number of topics, including logic, ethics, and metaphysics.


In philosophy, a paradox or state of puzzlement; in rhetoric, a useful expression of doubt.


A classical Greek (Athenian) philosopher credited as one of the founders of Western philosophy. Known for a question-answer style of examination.


The student of Socrates and author of The Republic. A philosopher and mathematician in classical Greece.

Classical Greece saw a flourishing of philosophers, especially in Athens during its Golden Age. Of these philosophers, the most famous are Socrates, Plato, and Aristotle.



Socrates. Bust of Socrates, currently in the Louvre.

Socrates, born in Athens in the 5th century BCE, marks a watershed in ancient Greek philosophy. Athens was a center of learning, with sophists and philosophers traveling from across Greece to teach rhetoric, astronomy, cosmology, geometry, and the like. The great statesman Pericles was closely associated with these new teachings, however, and his political opponents struck at him by taking advantage of a conservative reaction against the philosophers. It became a crime to investigate issues above the heavens or below the earth because they were considered impious. While other philosophers, such as Anaxagoras, were forced to flee Athens, Socrates was the only documented individual charged under this law, convicted, and sentenced to death in 399 BCE. In the version of his defense speech presented by Plato, he claims that the envy others experience on account of his being a philosopher is what will lead to his conviction.

Many conversations involving Socrates (as recounted by Plato and Xenophon) end without having reached a firm conclusion, a style known as aporia. Socrates is said to have pursued this probing question-and-answer style of examination on a number of topics, usually attempting to arrive at a defensible and attractive definition of a virtue. While Socrates’ recorded conversations rarely provide a definitive answer to the question under examination, several maxims or paradoxes for which he has become known recur. Socrates taught that no one desires what is bad, and so if anyone does something that truly is bad, it must be unwillingly or out of ignorance; consequently, all virtue is knowledge. He frequently remarks on his own ignorance (claiming that he does not know what courage is, for example). Plato presents Socrates as distinguishing himself from the common run of mankind by the fact that, while they know nothing noble and good, they do not know that they do not know, whereas Socrates knows and acknowledges that he knows nothing noble and good.

Socrates was morally, intellectually, and politically at odds with many of his fellow Athenians. When he was on trial, he used his method of elenchos, a dialectic method of inquiry that resembles
the scientific method, to demonstrate to the jurors that their moral values are wrong-headed. He tells them they are concerned with their families, careers, and political responsibilities when they ought to be worried about the “welfare of their souls.” Socrates’ assertion that the gods had singled him out as a divine emissary seemed to provoke irritation, if not outright ridicule. Socrates also questioned the Sophistic doctrine that arete (virtue) can be taught. He liked to observe that successful fathers (such as the prominent military general Pericles) did not produce sons of their own quality. Socrates argued that moral excellence was more a matter of divine bequest than parental nurture.



Plato. A copy of Plato’s portrait bust by Silanion.

Plato was an Athenian of the generation after Socrates. Ancient tradition ascribes 36 dialogues and 13 letters to him, although of these only 24 of the dialogues are now universally recognized as authentic. Most modern scholars believe that at least 28 dialogues, and two of the letters, were in fact written by Plato, although all of the 36 dialogues have some defenders. Plato’s dialogues feature Socrates, although not always as the leader of the conversation. Along with Xenophon, Plato is the primary source of information about Socrates’ life and beliefs, and it is not always easy to distinguish between the two.

Much of what is known about Plato’s doctrines is derived from what Aristotle reports about them, and many of Plato’s political doctrines are derived from Aristotle’s works, The Republic, the Laws, and the Statesman. The Republic contains the suggestion that there will not be justice in cities unless they are ruled by philosopher kings; those responsible for enforcing the laws are compelled to hold their women, children, and property in common; and the individual is taught to pursue the common good through noble lies. The Republic determines that such a city is likely impossible, however, and generally assumes that philosophers would refuse to rule if the citizenry asked them to, and moreover, the citizenry would refuse to compel philosophers to rule in the first place.

“Platonism” is a term coined by scholars to refer to the intellectual consequences of denying, as Plato’s Socrates often does, the reality of the material world. In several dialogues, most notably The Republic, Socrates inverts the common man’s intuition about what is knowable and what is real. While most people take the objects of their senses to be real if anything is, Socrates is contemptuous of people who think that something has to be graspable in the hands to be real. Socrates’s idea that reality is unavailable to those who use their senses is what puts him at odds with the common man and with common sense. Socrates says that he who sees with his eyes is blind, and this idea is most famously captured in his allegory of the cave, a paradoxical analogy wherein Socrates argues that the invisible world is the most intelligible and that the visible world is the least knowable and most obscure. In the allegory, Socrates describes a gathering of people who have lived chained to the wall of a cave facing a blank wall. The people watch shadows projected on the wall from the fire burning behind them, and the people begin to name and describe the shadows, which are the closest images they have to reality. Socrates then explains that a philosopher is like a prisoner released from that cave who comes to understand the shadows on the wall are not reality.



Aristotle. Roman copy in marble of a Greek bronze bust of Aristotle by Lysippus, c. 330 BCE. The alabaster mantle is modern.

Aristotle moved to Athens from his native Stageira in 367 BCE, and began to study philosophy, and perhaps even rhetoric, under Isocrates. He eventually enrolled at Plato’s Academy. He left Athens approximately twenty years later to study botany and zoology, became a tutor of Alexander the Great, and ultimately returned to Athens a decade later to establish his own school, the Lyceum. He is the founder of the Peripatetic School of philosophy, which aims to glean facts from experiences and explore the “why” in all things. In other words, he advocates learning by induction.

At least 29 of Aristotle’s treatises have survived, known as the corpus Aristotelicum, and address a variety of subjects including logic, physics, optics, metaphysics, ethics, rhetoric, politics, poetry, botany, and zoology. Aristotle is often portrayed as disagreeing with his teacher, Plato. He criticizes the regimes described in Plato’s Republic and Laws, and refers to the theory of forms as “empty words and poetic metaphors.”  He preferred utilizing empirical observation and practical concerns in his works. Aristotle did not consider virtue to be simple knowledge as Plato did, but founded in one’s nature, habit, and reason. Virtue was gained by acting in accordance with nature and moderation.