Ancient Philosophy: Key Concepts & Beliefs

Instructor: David Boyles

David has a Master's in English literature and is completing a Ph.D. He has taught college English for 6 years.

Philosophy in many ways can be seen as an ongoing argument between different schools of thought about the nature of existence and knowledge. Ancient philosophers are often divided into competing schools such as Sophism, Platonism, Epicureanism, and Stoicism.

Schools of Thought

Philosophy, the study of the fundamental nature of knowledge, existence, and being, can be seen in many ways as an argument that has been going on for thousands of years. Dealing with complex abstract ideas about the most important questions of who we are and how we function in the world, philosophers must form detailed justifications for their worldviews and compete with other philosophers who oppose them.

This ongoing argument leads philosophers to break into differing schools of philosophy. A school of philosophy is a group of philosophers who share basic assumptions about the world, though they do not necessarily always agree with each other on every point.

These schools of philosophy date back to the discipline's earliest days in ancient Greece and Rome. Important ancient schools of philosophical thought include Sophism, Platonism, Epicureanism, and Stoicism.


Sophism is one of the earliest schools of philosophy, coming into existence in the 7th and 6th centuries BCE. The term 'Sophist' originally meant any wise person and was a general term for a philosopher in this period. The Sophists are a less well-defined school than some of the others we will look at, though they did share some underlying principles and assumptions.

Sophists were defined by their belief in relative truth. They believed that there was no absolute truth and, therefore, that two points of view could be equally true at the same time. In other words, my belief that the Greek gods like Zeus are not real is equally as valid as your belief that they are.

Following from this relativistic view, Sophists were skeptical about religion and the legal system. A famous Sophistic quotation from Thrasymachus says 'Justice is nothing other than the advantage of the stronger.' In other words, a person goes to jail not because he is guilty of a crime, but because he has less power than the people who put him there. In addition to Thrasymachus, other famous Sophists include Thales of Miletus and Gorgias.

The Sophists were opposed by Socrates and his student Plato. Plato characterized the Sophists as dishonest charlatans who used rhetorical trickery and fallacious reasoning to deceive their audiences and students.


Named for its founder, Plato, Platonism is by far the most influential of the ancient schools of philosophy. In many ways, it is a direct response to the relativism of the Sophists.

Platonism's most famous tenant is the Theory of Forms. It argues that there is an eternal universe where ideas exist prior to taking material form and the material reality we see around us is only a pale reflection of that eternal truth. Platonists believed the job of the philosopher is to understand and get to that eternal truth as much as possible.

Furthermore, Platonism argues that knowledge and ethics are innate because our soul remembers the eternal forms. Therefore, it is our responsibility to bring our actions and knowledge in line with those forms as much as we can.


Epicureanism was founded around 307 BCE by the philosopher Epicurus and had a long life, persisting for hundreds of years into the height of the Roman Empire. It would become one of the most important Roman philosophies during the Empire.

Epicureanism is a materialist philosophy that argues against Platonism. Epicurus taught that the aim of life was to achieve tranquility through the pursuit of modest pleasures. He believed that living a simple, moderate life and limiting one's desires would lead one to this tranquil state.

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