Eudaimonia and the Function Argument

Nicomachean Ethics Book I opens by identifying eudaimonia — usually rendered "happiness" but closer in sense to "flourishing" or "living well and faring well" — as the highest human good, the end pursued for its own sake and for the sake of which all other goods are pursued (NE 1097a15-b21). To determine what eudaimonia consists in, Aristotle offers the celebrated "function argument" (ergon argument) at 1097b22-1098a20: just as a flute-player, sculptor, or craftsman, and indeed every bodily organ, has a characteristic function whose good performance defines its excellence, human beings as such must likewise have a distinctive function. Since nutrition and growth are shared with plants and perception is shared with animals, the function peculiar to human beings is activity of the rational part of the soul, and their good is therefore "an activity of soul in accordance with virtue, and if there are more virtues than one, in accordance with the best and most complete" (NE 1098a16-18).