In Nicomachean Ethics 1.7, Aristotle claims that to discover the human good we must identify the function of a human being. He argues that the human function is rational activity. Our good is therefore rational activity performed well, which Aristotle takes to mean in accordance with virtue. This argument has been criticized at almost every point. This chapter defends Aristotle's argument from these criticisms. Drawing on the account of form and matter in Aristotle's Metaphysics, it argues that “function” does not mean purpose but rather a way of functioning — how a thing does what it does. The way human beings do things is by making rational choices. The human good or happiness is not merely a result of rational choice, but consists in it, because a rational action or activity is one whose principle expresses the agent's conception of what is worth doing for the sake of what.
Keywords: action, Aristotle, choice, form, function, happiness, good, purpose, rational, virtue