Aristotle (384–322 BCE) was a philosopher and investigator of nature in ancient Greece. His surviving works address reasoning, living organisms, change, being, human conduct, political communities, and literary composition. A student of Plato and tutor of Alexander the Great, he developed approaches that combined conceptual analysis, systematic argument, and observation. His writings became foundational texts in several branches of philosophy and influenced Greek, Arabic, Jewish, and Latin intellectual traditions.
Life and school
Aristotle was born in Stagira, in northern Greece. His father, Nicomachus, served as physician to Amyntas III of Macedon. Around 367 BCE, Aristotle entered Plato’s Academy in Athens, where he remained for approximately twenty years, until Plato’s death in 347 BCE.
He subsequently worked in Assos and on Lesbos, conducting research that included the study of animals. Around 343 BCE, Philip II of Macedon invited him to tutor the young Alexander. The precise content and extent of this instruction are uncertain.
Returning to Athens in 335 BCE, Aristotle established his school at the Lyceum. Its members became known as Peripatetics, a name associated with the school’s covered walks. After Alexander’s death in 323 BCE, Aristotle left Athens amid hostility toward Macedonian connections. He died the following year in Chalcis on Euboea.
Writings and methods
Most surviving Aristotelian works are technical treatises rather than polished compositions intended for a general readership. They are often understood as texts connected with teaching and research, although their composition and editorial history remain debated. Many of his dialogues and other writings are lost.
Major surviving works include the Categories, Prior Analytics, Posterior Analytics, Physics, Metaphysics, On the Soul, Nicomachean Ethics, Politics, Rhetoric, and Poetics. The logical works were later grouped under the title Organon, meaning “instrument.”
Aristotle distinguished theoretical inquiry, practical deliberation, and productive expertise. Different subjects required different standards of precision: ethical questions, for example, could not generally receive the same exact treatment as mathematics. His investigations frequently began by reviewing earlier thinkers and accepted opinions, identifying difficulties, and developing explanatory distinctions.
Logic and knowledge
Aristotle produced the earliest surviving systematic theory of logic. In the Prior Analytics, he analyzed the syllogism, a form of deductive reasoning in which a conclusion follows necessarily from specified premises. His account distinguished arguments by their structure rather than merely by their subject matter.
The Posterior Analytics examined scientific knowledge. To understand something scientifically was not simply to know that it was true, but to grasp why it was true through an explanation of its cause. Demonstration therefore required appropriate starting principles, not just formally correct inference.
Perception, memory, experience, and inductive reasoning contributed to acquiring universal principles. Nevertheless, Aristotle did not treat every first principle as the conclusion of a further proof; otherwise explanation would face an infinite regress.
Being, change, and explanation
Aristotle’s metaphysics investigates being as being, substance, and first principles. Against Plato’s separation of Forms from sensible things, he generally located the forms of natural substances within the things themselves.
His account of hylomorphism describes ordinary material substances through matter and form: matter is what something is made from, while form is its organization or defining actuality. The distinction between potentiality and actuality explains how change can occur without something arising from absolute nothingness.
The doctrine of the four causes identifies complementary explanatory questions: material, formal, efficient, and final. A bronze statue, for example, can be explained through its bronze, its shape, its maker, and its purpose. Aristotle’s account of causation thus extends beyond the modern emphasis on preceding events.
He also argued for an unmoved mover, an ultimate principle of motion that moves as an object of desire or thought rather than through physical intervention.
Nature and living organisms
Aristotle’s natural philosophy studied motion, time, place, continuity, and change. His cosmology placed a spherical, stationary Earth at the center of the universe and distinguished terrestrial processes from celestial motions. These physical doctrines were later displaced by developments associated with the Scientific Revolution.
His contributions to biology included detailed descriptions of animal anatomy, reproduction, development, and behavior. He compared organisms and sought explanations connecting bodily structures with their functions. His observations were substantial, but some reports and explanatory assumptions were mistaken.
In On the Soul, the soul is principally the form or actuality of a living body, not simply a separate occupant of it. He distinguished capacities for nutrition, sensation, desire, movement, and thought.
Ethics, politics, and literary theory
In ethics, Aristotle identified eudaimonia, commonly translated as flourishing or happiness, as the highest human good. It consists in activity in accordance with excellence over a complete life, rather than a passing emotional state. His account is a central source for virtue ethics.
Moral virtues develop through habituation. Many involve a mean between excess and deficiency, determined by practical wisdom rather than arithmetic averaging. Friendship, external circumstances, and contemplation also occupy important places in his ethical writings.
His political philosophy treats the polis as a community directed toward living well. He compared constitutions and distinguished government serving a common interest from rule serving rulers’ interests. His defenses of natural slavery and unequal gender roles reflect positions rejected by modern egalitarian thought.
The Poetics analyzes poetry, especially tragedy, through imitation, plot, character, and emotional effects. Aristotle gave particular importance to the organization of action.
Transmission and reception
Greek commentators preserved and interpreted Aristotle’s works. Syriac and Arabic translations supported extensive study in the Islamic world. During the Middle Ages, translations from Arabic and Greek expanded their availability in Latin. Thomas Aquinas incorporated Aristotelian concepts into Christian theology while modifying them. Aristotle’s authority was never uncontested: interpreters disputed his doctrines, and early modern investigators challenged his natural philosophy.