Megarian School of Ancient Greek Philosophy Texts

Megarian School

The Megarian school was founded around 400 BCE in Megara by Eucleides (Euclid) of Megara, a pupil of Socrates. He established a school of disputation that blended Socratic ethics with Parmenidean monism.

Core Teachings

Eucleides started from the Socratic principle that virtue is knowledge. He combined this with the Parmenidean view that reality is one, unchanging, and eternal, separate from sense experience. For the Megarians, the good was singular and could be called wisdom, god, or reason. They denied reality to its opposite.

The school’s primary method was dialectic, using rigorous question-and-answer techniques to defend their theses. They focused on logical disputation and the analysis of whole propositions, differing from Aristotle’s focus on predicates. They rejected Aristotelian categories, the reality of motion, and the concept of potentiality. For them, only what is actually true now or will be true is possible.

Their work produced famous logical paradoxes and advanced modal logic. Diodorus Cronus formulated the “Master Argument,” which concluded that only what is or will be true is possible. Megarian philosophers also debated the nature of conditional statements (“if-then” sentences) with figures like Philo the Dialectician.

Key Figures

Eucleides of Megara (fl. c. 400 BCE): Founder of the school. He authored Socratic dialogues and synthesized Socratic ethics with Parmenidean monism. Stilpo (c. 380–300 BCE): A successor known for his work in ethics. He influenced the development of Stoicism. Eubulides of Miletus (fl. 4th century BCE): A critic of Aristotle and the inventor of several logical paradoxes. Diodorus Cronus (d. c. 284 BCE): Developed the Master Argument concerning possibility and necessity. Philo the Dialectician: Engaged in debates with Diodorus over the truth conditions of conditional statements. Ichthyas: Contributed to the formalization of logical paradoxes. Clinomachus of Thurii: An early figure associated with formalizing statements in logic.

Historical Development

The school flourished in the 4th and 3rd centuries BCE. It began in Megara with Eucleides’s ethical and metaphysical synthesis. Over time, the focus shifted intensely toward logic, paradox, and eristic (debate for its own sake). Key figures taught in Athens and other cities, not just Megara. This later, logic-focused phase led to the school also being called the Dialectical or Eristic school. The school’s activities spanned into the early 3rd century BCE.