Happiness and the human function

The Nicomachean Ethics opens with a deceptively simple observation: every action and every pursuit aims at some good (NE I.1, 1094a). You cook to eat, you eat to be healthy, you stay healthy to live well. Ends chain into ends.

But this chain can’t go on forever, or desire would be empty. There must be some highest good — an end we seek for its own sake, and for the sake of which we seek everything else. Name it, and you have named the target of a whole human life (NE I.2, 1094a18–22).

Aristotle gives that highest good a name: eudaimonia (often translated “happiness,” but better rendered flourishing or living well). Everyone agrees on the word — but the moment you ask what eudaimonia actually consists in, agreement collapses (NE I.4, 1095a17–22).

So Aristotle surveys the candidates. The many say eudaimonia is pleasure — but that, he notes, is a life fit for cattle. The refined say honor — but honor depends on the people giving it, so it is too shallow and external to be the good we’re after. Others say wealth — but wealth is merely useful, sought for the sake of something else, never for its own sake (NE I.5).

To settle the dispute, Aristotle turns to his signature move: the function argument (ergon argument, NE I.7, 1097b22–1098a20). Ergon = characteristic work or function. The good of a thing, he claims, lies in performing its characteristic function well.

So what is the distinctively human ergon? Not mere living — plants do that. Not sense-perception — animals do that. What is left, unique to us, is the life of the rational part of the soul: activity in accordance with, or not without, reason (logos).

Put it together and you get Aristotle’s definition: the human good is activity of the soul in accordance with virtue (aretē = excellence), and if there are several virtues, in accordance with the best and most complete — in a complete life (NE I.7, 1098a16–18).

Two more conditions follow. First, “in a complete life”: one swallow doesn’t make a spring, and one good day doesn’t make a person blessed. Eudaimonia is a life-long achievement (NE I.7, 1098a18–20).

Second, virtue alone is not quite enough. Aristotle grants that flourishing also needs some external goods — friends, resources, decent fortune. His example is Priam, king of Troy: a man of excellent character who ended his life watching his city burn and his sons slain. We hesitate to call such a life eudaimōn (NE I.9–10, 1100a).