Aristotle’s conception of virtue as something learned through habit rather than through reasoning makes a great deal of practical sense. We can generally trace unpleasantness to the circumstances in which a person grew up, and it is difficult to make an unpleasant person pleasant simply by providing reasons for behaving more pleasantly.
The virtues Aristotle lists, then, reflect the commonly held values of a properly raised, aristocratic Athenian. If we disagree with Aristotle’s choices of virtues, we are unlikely to find a compelling argument in his work to change our mind: by Aristotle’s own admission, reasoning is unlikely to teach us to appreciate virtue if we have not been raised with the right habits.
One of the most celebrated and discussed aspects of Aristotle’s Ethics is his Doctrine of the Mean, which holds that every virtue is a mean between the vicious extremes of excess and deficiency. This is not a strict rule, as Aristotle himself points out: there is no precise formula by which we can determine exactly where this mean lies, largely because the mean will vary for different people.
That there should be no fixed rule to determine where the mean lies is a direct consequence of his doctrine that virtue is something learned through habit, not through reason. If we could reason our way into virtue, we might be able to set out precise rules for how to behave in different situations. According to Aristotle’s view, however, a virtuous person is naturally inclined to choose the correct behavior in any situation without appealing to rules or maxims.
In Book I, Chapter 3, and Book II, Chapter 2, Aristotle warns us that our inquiry is at best an imprecise one. Bearing in mind that virtue for Aristotle is a set of innate dispositions, not a reasoned set of rules, we can understand these warnings to be more than simple hedges. Aristotle is not avoiding precision but saying that precision is impossible because there are no fixed rules of conduct that we can follow with confidence.