Aristotle (384–322 BC)
Authors: Irwin T.H. 
Published: September 2018

Aristotle of Stagira is one of the two most important philosophers of the ancient world, and one of the four or five most important of any time or place. He was not an Athenian, but he spent most of his life as a student and teacher of philosophy in Athens. For twenty years he was a member of Plato’s Academy; later he set up his own philosophical school, the Lyceum. During his lifetime he published philosophical dialogues, of which only fragments now survive. The ‘Aristotelian corpus’ (1462 pages of Greek text, including some spurious works) is probably derived from the lectures that he gave in the Lyceum.
Aristotle is the founder not only of philosophy as a discipline with distinct areas or branches, but, still more generally, of the conception of intellectual inquiry as falling into distinct disciplines. He insists, for instance, that the standards of proof and evidence for deductive logic and mathematics should not be applied to the study of nature, and that neither of these disciplines should be taken as a proper model for moral and political inquiry. He distinguishes philosophical reflection on a discipline from the practice of the discipline itself. The corpus contains contributions to many different disciplines, not only to philosophy.
Some areas of inquiry in which Aristotle makes a fundamental contribution are these:
(1) Logic. Aristotle’s Prior Analytics constitutes the first attempt to formulate a system of deductive formal logic, based on the theory of the ‘syllogism’. The Posterior Analytics uses this system to formulate an account of rigorous scientific knowledge. ‘Logic’, as Aristotle conceives it, also includes the study of language, meaning and their relation to non-linguistic reality; hence it includes many topics that might now be assigned to philosophy of language or philosophical logic (Categories, De Interpretatione, Topics).
(2) The study of nature. About a quarter of the corpus (see especially the History of Animals, Parts of Animals, and Generation of Animals; also Movement of Animals, Progression of Animals) consists of works concerned with biology. Some of these contain collections of detailed observations. (The Meteorology contains a similar collection on inanimate nature.) Others try to explain these observations in the light of the explanatory scheme that Aristotle defends in his more theoretical reflections on the study of nature. These reflections (especially in the Physics and in Generation and Corruption) develop an account of nature, form, matter, cause and change that expresses Aristotle’s views about the understanding and explanation of natural organisms and their behaviour. Natural philosophy and cosmology are combined in On the Heavens.
(3) Metaphysics. In his reflections on the foundations and presuppositions of other disciplines, Aristotle describes a universal ‘science of being qua being’, the concern of the Metaphysics. Part of this universal science examines the foundations of inquiry into nature. Aristotle formulates his doctrine of substance, which he explains through the connected contrasts between form and matter, and between potentiality and actuality. One of his aims is to describe the distinctive and irreducible character of living organisms. Another aim of the universal science is to use his examination of substance to give an account of divine substance, the ultimate principle of the cosmic order.
(4) Philosophy of mind. The doctrine of form and matter is used to explain the relation of soul and body, and the different types of soul found in different types of living creatures. In Aristotle’s view, the soul is the form of a living body. He examines the different aspects of this form in plants, non-rational animals and human beings, by describing nutrition, perception, thought and desire. His discussion (in On the Soul, and also in the Parva Naturalia) ranges over topics in philosophy of mind, psychology, physiology, epistemology and theory of action.
(5) Ethics and politics (Nicomachean Ethics, Eudemian Ethics, Magna Moralia). In Aristotle’s view, the understanding of the natural and essential aims of human agents is the right basis for a grasp of principles guiding moral and political practice. These principles are expressed in his account of human wellbeing, and of the different virtues that constitute a good person and promote wellbeing. The description of a society that embodies these virtues in individual and social life is a task for the Politics, which also examines the virtues and vices of actual states and societies, measuring them against the principles derived from ethical theory.
(6) Literary criticism and rhetorical theory (Poetics, Rhetoric). These works are closely connected both to Aristotle’s logic and to his ethical and political theory.