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Aristotle (384–322 BCE)

Aristotle built the first comprehensive philosophical system — logic, metaphysics, physics, biology, ethics, politics, poetics — and it dominated Western thought for two millennia. His central framework is teleological: everything has a telos (end, purpose, function), and understanding a thing means understanding what it is for. The four causes — material (what it is made of), formal (its structure), efficient (what brought it about), and final (what it is for) — provide the explanatory framework. In biology, this produced the first systematic natural history: observation, classification, comparative anatomy, and functional explanation across hundreds of species. In ethics, it produced the virtue tradition: the good life (eudaimonia) is the life lived in accordance with the excellences of character that fulfil the human function. The Aristotelian framework was recovered in the medieval period by Thomas Aquinas, challenged by the scientific revolution, and revived in the twentieth century by MacIntyre and others. Whether teleology can survive the Darwinian revolution — which explains apparent purpose through mechanism rather than final causes — is the deepest question in Aristotle’s modern reception.

Life

Born 384 BCE in Stagira, a Greek colony in Chalcidice (northern Greece). His father Nicomachus was physician to Amyntas III, king of Macedon — a connection to the Macedonian court that would later bring Aristotle to Alexander the Great. Orphaned early and raised by a guardian.

Entered Plato’s Academy in Athens at seventeen (367 BCE) and remained for twenty years, until Plato’s death in 347 BCE. The relationship with Plato was formative and never fully resolved: Aristotle rejected the theory of Forms (universals existing in a separate realm) but retained Plato’s commitment to the intelligibility of nature and the possibility of knowledge.

Left Athens after Plato’s death. Spent years in Asia Minor and Lesbos, where he conducted the biological fieldwork — particularly marine biology on the coast of Lesbos — that produced Historia Animalium and the other biological works. Appointed tutor to the young Alexander of Macedon (343 BCE); the tutoring lasted approximately three years and its intellectual content is unknown.

Returned to Athens and founded the Lyceum (335 BCE), a school and research institution. The Lyceum’s distinctive practice was the peripatetic method — philosophical discussion conducted while walking. Aristotle’s surviving works are largely thought to be lecture notes, not polished publications, which accounts for their compressed and sometimes obscure style. After Alexander’s death in 323 BCE, anti-Macedonian sentiment in Athens made Aristotle’s position dangerous. He withdrew to Chalcis on Euboea, reportedly saying he would not allow Athens to “sin twice against philosophy” (referring to Socrates’ execution). Died 322 BCE in Chalcis.

Teleology and the four causes

Aristotle’s explanatory framework is organised around four kinds of cause (aitia):

Material cause — what a thing is made of. The bronze of a statue, the wood of a table.

Formal cause — the structure, pattern, or definition that makes a thing what it is. The shape of the statue, the design of the table.

Efficient cause — the agent or process that brought the thing into being. The sculptor who shaped the bronze, the carpenter who built the table.

Final cause — the end, purpose, or function the thing serves. The purpose for which the statue was commissioned, the function the table performs.

The four causes work together in biological explanation, where Aristotle’s teleology is most productive. Why does an animal have eyes? Material: they are made of specific tissues. Formal: they have a specific structure (lens, pupil, humour). Efficient: they develop through a specific embryological process. Final: they are for seeing. Aristotle insists that all four are needed for a complete explanation, and that the final cause — the function — is the most important: “Nature does nothing in vain.”

The relationship between Aristotelian teleology and Darwinian natural selection is the deepest tension in the modern reception. Darwin’s mechanism explains apparent purpose without final causes: eyes exist not because they are for seeing but because organisms with better eyes outreproduced those with worse ones. Whether this eliminates teleology or merely reinterprets it — whether natural selection is the efficient cause of features that genuinely have final causes, or whether “function” in biology is a useful shorthand for “consequence of selection” — is debated between eliminativists and neo-Aristotelian naturalists.

Biology

Aristotle was the first systematic biologist. His biological works — Historia Animalium (“Inquiry into Animals”), De Partibus Animalium (“On the Parts of Animals”), De Generatione Animalium (“On the Generation of Animals”) — classify, describe, and explain the anatomy, physiology, reproduction, and behaviour of over 500 animal species. The observations are based on direct dissection and field study, much of it conducted on Lesbos. The scope and accuracy of the work were not surpassed for nearly two thousand years.

The classificatory scheme distinguishes animals by blood (roughly: vertebrates and invertebrates), by habitat, by mode of reproduction, and by structural features. The classification is not a taxonomy in the modern sense — Aristotle did not have a theory of species as fixed natural kinds — but it provided the framework for biological classification until Linnaeus. The explanatory method is functional: parts are explained by what they do, and animals are compared by how the same function is achieved with different structures (homology, in later terminology, though Aristotle did not have the concept of common descent).

Charles Darwin acknowledged the debt: “Linnaeus and Cuvier have been my two gods, though in very different ways; but they were mere schoolboys to old Aristotle.”

Virtue ethics

The Nicomachean Ethics argues that the good for a human being is eudaimonia — variously translated as happiness, flourishing, or well-being. Eudaimonia is not a feeling but an activity: the activity of living well and doing well, in accordance with the virtues (excellences of character). The virtues — courage, temperance, justice, practical wisdom (phronesis), among others — are dispositions of character acquired through practice and habit, not through theoretical instruction. Virtue is a mean between extremes: courage is the mean between cowardice and recklessness; generosity is the mean between miserliness and extravagance. The mean is not a mathematical midpoint but the right response in the right circumstances, determined by practical wisdom.

The framework is teleological: the virtues are the excellences needed to fulfil the human function (ergon). Just as the function of a knife is to cut and a good knife cuts well, the function of a human being is to live a life of rational activity, and a good human being lives it well. The claim depends on there being a determinate human function — a claim MacIntyre’s After Virtue attempted to recover and that critics have challenged on both Darwinian and liberal-individualist grounds.

Where Aristotle stops

The teleological framework — everything has a purpose, and understanding requires identifying it — was the most productive explanatory scheme in the history of natural philosophy and the one most decisively challenged by modern science. In physics, the scientific revolution (Galileo, Newton) replaced teleological explanation with mechanical explanation: falling bodies do not move toward their natural place; they obey the law of gravitation. In biology, Darwin replaced teleological explanation with selectionist explanation: organisms are not designed for their environments; they are selected by their environments. Whether this eliminates teleology or relocates it is the central philosophical question. Philippa Foot and Alasdair MacIntyre have argued for a neo-Aristotelian naturalism in which natural teleology survives within biology (organisms genuinely have functions, and the virtues genuinely fulfil the human function). Critics, including Bernard Williams, have argued that the human-function claim cannot survive the recognition that human beings are not designed for anything — that there is no ergon.

The logic — the syllogism and the theory of the categories — dominated for two thousand years and was replaced. Frege’s predicate logic (1879) showed that Aristotelian logic cannot handle multiple quantifiers, relational predicates, or the logical structure of mathematical reasoning. The replacement was not a correction of errors within the system but a demonstration that the system’s expressive power is fundamentally limited. Aristotle’s logic was not wrong; it was incomplete, in a way that two millennia of work within it had not revealed.

The political and ethical framework excluded women, slaves, and non-Greeks from full participation in the good life — not as contingent social facts but as features of Aristotle’s account of human nature. Women lack the deliberative faculty in its full form; slaves are natural slaves, suited by nature to be ruled; non-Greeks are barbarians. These exclusions are structural, not incidental, and modern Aristotelians (including MacIntyre) have had to address whether the virtue-ethics framework can survive their removal or whether it was built on them.

Key works

See also: MacIntyre · Darwin · Frege