Aristotle
A student of Plato who broke sharply with his teacher's otherworldly Forms, Aristotle insisted that form and matter are found together in the things around us. He wrote foundational treatises across logic, biology, physics, metaphysics, ethics, politics, and rhetoric, and his method of careful observation and classification shaped science for two millennia. Later thinkers simply called him 'the Philosopher.'
Schools
Key concepts
Core works
Nicomachean Ethics
c. 340 BCEAristotle asks what the good life for a human being is and answers: eudaimonia, usually translated as flourishing or happiness — not a feeling but an activity of the soul in accordance with virtue over a complete life. Because humans are rational animals, our flourishing lies in exercising reason well. Virtue of character is a settled disposition to feel and act rightly, lying at a mean between excess and deficiency relative to the situation: courage between rashness and cowardice, generosity between waste and stinginess. Such virtue is acquired by habit, guided by practical wisdom. The work ends by ranking the contemplative life as the highest, since it most fully expresses our rational nature.
Read summary →
Metaphysics
c. 340 BCEThe Metaphysics investigates 'being as being' — what it means for anything to exist at all. Aristotle surveys earlier thinkers, then develops his own account of substance as the primary kind of being, analyzed through the interplay of form and matter and the four causes (material, formal, efficient, and final). He distinguishes potentiality from actuality to explain change, and argues that the chain of motion in the cosmos requires an unmoved mover — a fully actual being that causes motion as an object of desire rather than by pushing. The treatise founds metaphysics as the study of first principles underlying every other inquiry.
Read summary →