Aristotle's function argument 1. The (special) function of a thing is what it alone does, or what it characteristically does, or what can best be done by means of it. [This is implicit here; see Republic 352e353a.] 2. The special function of a human involves reasoning, since this alone is not shared with other living beings. (1098a14) 3. There are two ways that human function involves reasoning: one part of the soul reason; one part has or does reasoning and thinking. (1098a45) listens to or obeys 4. The function of a thing is, in the fullest sense, an activity (rather than a mere capacity). (1098a57) 5. So: the [distinctive] human function is activity of the soul that reason, or by obeying reason. [from 2, 3 and 4] (1098a7) 6. The function of a thing is the same as the function of a harpist). (1098a8) good 7. A good or excellent example of something does its function expresses reason, either by having or excellent example of that kind (e.g. well. (1098a12) 8. So: a good or excellent person is one whose activity expresses reason well. [from 5, 6 and 7] (1098a14 15) 9. Doing something well is doing it in accordance with its specic virtue. (1098a1516) [See also NE II.6, 1106a17] 10. So: the good of a human is to perform the activity of reason, in a way that expresses virtue. [from 8, 9] (1098a16) 11. (Aristotle adds:) The human good is activity in accordance with the a complete life. (1098a1820) best and most complete virtue, in