Aristotelian School of Ancient Greek Philosophy Texts

Aristotelianism began with Aristotle (384–322 BCE). After serving as tutor to Alexander the Great, he returned to Athens and founded the Lyceum, also called the Peripatetic school, around 335 BCE. The Lyceum functioned as a research institution, devoted to systematic inquiry and close observation of the tangible world, and Aristotle's philosophy is a single comprehensive system in which logic, the study of being, ethics, politics, and natural inquiry form connected parts.

In his first philosophy the primary reality is οὐσία, the being of each individual thing. Every such thing is a composite of εἶδος, its structure or defining character, and ὕλη, its material. Each thing also carries a τέλος, an end toward which it moves: an acorn's end is to become an oak. For human beings this end is εὐδαιμονία, flourishing or living well.

His ethics centres on ἀρετή, excellence of character, understood as a stable ἕξις, an active condition, found at the mean between extremes of excess and deficiency. Courage, for example, lies between rashness and cowardice. Acquiring these excellences is a matter of habituation guided by φρόνησις, practical wisdom.

Aristotle's logic rests on the syllogism, a form of deductive argument that remained the framework of logical study for centuries. In politics he treats the human being as ζῷον πολιτικόν, a creature whose end is fulfilled in community, and he favours a constitution blending monarchy, aristocracy, and democratic elements. His natural philosophy explains phenomena through four causes: the material, what a thing is made of; the formal, its structure; the efficient, what produced it; and the final, its end.

The school flourished at the Lyceum under Theophrastus (c. 371–287 BCE), who advanced botany as well as the school's theoretical work, and Strato of Lampsacus (c. 335–269 BCE), the third head, who concentrated on physical theory; its distinct identity faded after the 1st century BCE, when Antiochus of Ascalon blended it with Platonism. Aristotle's treatises were preserved and commented on by Islamic scholars such as Avicenna and Averroes during the Middle Ages and reached medieval Europe through Latin translations, prompting a revival in which Thomas Aquinas (1225–1274 CE) used Aristotelian logic and the study of οὐσία as the framework for Christian theology, a synthesis known as Scholasticism. Elements of Aristotelian thought re-emerged in Renaissance humanism and again in the 20th-century revival of the ethics of ἀρετή.