Virtue, the mean, and weakness of will

Aristotle divides the soul’s excellences into two families. Intellectual virtues (like wisdom and understanding) grow mainly through teaching, and so need time and experience. Virtues of character (ēthikē aretē — “moral” virtues like courage and generosity) grow through habituation (ethismos). The very word ēthikē is a twist on ethos, habit (NE II.1, 1103a14–18).

This is a radical claim: we are not born virtuous, nor made virtuous by nature — but we are by nature able to acquire virtue, and we complete it by practice. “We become just by doing just acts, temperate by doing temperate acts, brave by doing brave acts” (NE II.1, 1103a34–b2).

The result of good habituation is a hexis (a stable disposition or settled state) — not a passing feeling, not a one-off act, but a reliable readiness to feel and act rightly. Virtue is a hexis, and it is this settledness that makes a person dependably good rather than accidentally good on a lucky day (NE II.5, 1105b25–26).

What content does this disposition have? Here comes Aristotle’s most famous doctrine: the Mean (mesotēs). Virtue of character is a disposition to feel emotions and perform actions rightly — at the right time, toward the right people, in the right way — which turns out to be a mean between two vices: one of excess and one of deficiency (NE II.6, 1106b16–23).

Take courage: the mean between rashness (too little fear, too much confidence) and cowardice (too much fear). Take generosity: the mean between prodigality (giving wildly) and stinginess (giving too little). The virtue sits between overshooting and undershooting the feeling or action.

So who fixes where the mean lies? Not a formula. The mean is “determined by reason (logos), as the person of practical wisdom (phronimos) would determine it” (NE II.6, 1106b36–1107a2). The virtuous person’s trained perception is the standard — a thread we pick up in the next lesson.

Aristotle now tightens the definition of a virtuous act. It’s not enough to do the right thing by accident. The agent must (1) act knowingly, (2) choose the act for its own sake, and (3) act from a firm and unchanging character (NE II.4, 1105a28–34). The act must flow from a settled self, not luck or imitation.

This makes voluntariness central. An act is voluntary (hekousion) when its origin is in the agent and they know the particulars; involuntary (akousion) when done under compulsion or through ignorance of the circumstances. Only voluntary actions are apt for praise and blame (NE III.1).

At the heart of voluntary action is choice (prohairesis): not desire, not mere wish, but deliberated desire — what you settle on after deliberation (bouleusis) about the things in your power. We deliberate not about ends but about the means to them (NE III.3). Prohairesis is the fingerprint of character on action.

Finally, the hardest case: akrasia (weakness of will, “incontinence”) — knowing the good yet doing the bad, overcome by appetite. Here Aristotle breaks openly with Socrates (NE VII.1–3, 1145b21ff).

Aristotle’s solution: the akratic person’s knowledge is present but not fully active (NE VII.3, 1147a10–24). Overpowered by appetite, they have the universal knowledge (“this sweet is unhealthy”) but fail to actualize it in the moment — like a person who is drunk, asleep, or reciting words without grasping them. Passion doesn’t erase the knowledge; it stops the knowledge from operating.