Aristotle

384–322 BCE. Twenty years a student in Plato‘s Academy, then Alexander’s tutor, then founder of the Lyceum — and the tradition’s first systematic critic of his own teacher.

About 31 treatises survive out of roughly 200, in the form of lecture notes. The organization is his own: theoretical sciences (metaphysics, physics, natural philosophy), practical (ethics, politics), productive (rhetoric, poetics), with logic standing outside as the Organon, the instrument the others use.

The load-bearing doctrines, per sep-aristotle:

• Syllogistic — the first formalized system of logic and valid inference, arranged so that every deduction reduces to a form you can see is valid.
• Four causes — material, formal, efficient, final. An explanation is complete when it says what a thing is made of, what structure it has, what brought it about, and what it is for.
• Hylomorphism — ordinary objects are composites of matter and form; potentiality and actuality describe the passage between them.
• Eudaimonia — the practical sciences ask what a life going well consists in.

The break with Plato

He rejects univocity: the assumption that “good” or “being” names one essence everywhere it appears. In its place, core-dependent homonymy — a term can have several senses that still hang together, because each depends on one primary sense. That is a different diagnosis of the forms than “they do not exist”; it says the demand for a single essence behind a single word was the error.

Why this matters to the corpus’s own arguments

• The final cause is the piece Descartes and the mechanists throw out, and discarding it is most of what “modern” means in western-philosophy. Spinoza goes furthest — nature acts for no end at all.
• Ethics as the study of a well-lived life, rather than of obligations, is the frame stoicism inherits and the one this spoke’s third through-line follows.
• Core-dependent homonymy is a working answer in epistemology and semantics still, which is why the entry is not merely historical.

Provenance: sep-aristotle (T1). Primary texts unread here.