The term justice can apply both to a general disposition in a person as well as to questions concerning exchanges and illegal infractions. Justice is a distinct kind of virtue because it encompasses all the other virtues and because it treats the interactions between people rather than just the dispositions of an individual person. Aristotle distinguishes between distributive justice, which deals with the distribution of goods among members of a community, and rectificatory justice, which deals with unjust gains or losses between two people, through trade, theft, or assault. Distributive justice accords goods and honor proportionately, giving most to those who deserve most, whereas rectificatory justice aims to restore imbalances. No one willingly suffers an injustice, and it is not possible to treat oneself unjustly. While the laws are a good guideline, they do not cover every particular case. On occasion, agreed-upon equity must settle cases that the laws do not.

Acting morally requires not only that we have all the moral virtues but also that we have the intellectual virtue of prudence, or practical reason. Prudence is one of five intellectual virtues, the other four of which are scientific knowledge, intuition, wisdom, and art or technical skill. Prudence is the kind of intelligence that helps us reason properly about practical matters. Having the right motives is a matter of having all of the moral virtues, but choosing the right course of action is a matter of prudence.

As well as plain, unthinking brutishness and vice, which are the opposite of virtue, people may also do wrong through incontinence, or a lack of self-control. Incontinence is not as bad as vice, since it is partially involuntary, but it is also harder to remedy, since it is unreasoned. Though we are led into incontinence from an excessive desire for pleasure, pleasure is generally a good thing. Our pursuit of the good life is itself the pursuit of pleasure, and pleasure only leads us astray when we have a defective character.

Friendship is an essential component of the good life. The best kind of friendship is one in which two people are attracted to each other because they admire each other’s virtue and where each friend takes more interest in giving love than in receiving. Inferior kinds of friendship are based on utility or pleasure. Our attitude toward ourselves reflects our attitude toward our friends: people who love and respect themselves are likely to treat their friends well. Self-love is more important than friendship, and people only look down on it because people who love themselves imperfectly seek honor or pleasure for themselves rather than goodness. Since friendship is essential to the good life, not even wholly self-sufficient people can be truly happy without friends.

Friendship is closely tied to justice, since both have to do with how we treat others, and Aristotle’s discussion of friendship reaches outward to encompass other forms of human interaction such as family relationships and government. The three good kinds of government are monarchy, aristocracy, and timocracy, which is a kind of democracy with a basic property requirement for voting rights. They are analogous, respectively, to a father–son relationship, a husband–wife relationship, and a brother–brother relationship. Corrupted monarchy becomes tyranny, corrupted aristocracy becomes oligarchy, and corrupted timocracy becomes democracy, by which Aristotle means a kind of mob rule.

The highest goal of all is rational contemplation, and the good life consists in pursuing this activity above all others. No one can live a life of pure contemplation, but we should aim to approximate this ideal as best as possible. Pleasure accompanies and perfects our activities, and a good person will feel the highest pleasure in this activity of rational contemplation. The practical sciences of ethics and politics are guides for dealing with our everyday lives and arranging things so that we can find the surest path to the good life.

Aristotle’s discussion of incontinence refines Socrates’ famous claim that no one ever knowingly does wrong. According to Socrates, ignorance is the source of all wrongdoing, and so perfect wisdom is the best guard against vice. The idea of incontinence—a rough translation of the Greek word akrasia, which more accurately translates as “lacking self-control”—raises a problem for this view because some people clearly do wrong knowingly. A person addicted to cigarettes might light up, saying, “I know this stuff is bad for me and I know I should quit, but I just can’t help it.” This person does not smoke because she is ignorant of the ill effects of smoking but because she lacks the self-control to do what she knows is right. Earlier in the Ethics, Aristotle suggests that virtue is, above all, a matter of habit, and someone raised with the wrong habits will inevitably fall into vice. Virtue, for Aristotle, is a matter of practice. For this reason, he differs from Socrates and Plato by saying that an intellectual understanding of virtue is not enough to guarantee virtue. We can do wrong knowingly if we have not been raised with the strength of character not to want to do wrong.

Aristotle’s emphasis on self-love makes more sense when we understand it in the context of the Greek city-state. His argument that self-love is more important than friendship positions him as one of the early proponents of ethical egoism, the view that if we all took proper care to become good people ourselves, the world would work out for the best and there would be no need for selflessness. This view may seem callous in the modern world of capitalist individualism, where looking out for number one often comes at the expense of others, but it is less odious in the context of Aristotle’s Greece. The Greek city-states were tightly knit communities, where citizens would identify themselves with their city to the extent that exile was considered a fate worse than death. In such a world, one’s own well-being was largely determined by the well-being of one’s city, so it would be in the self-interest of every citizen to look out for the welfare of the city-state and its citizenry. Aristotle’s conception of self-love, then, is much more community oriented than the self-love espoused by modern pseudophilosophers such as Ayn Rand.

Aristotle’s ultimate conclusion that rational contemplation is the highest good is based on a teleological conception of human nature. According to Aristotle, everything in nature has a telos, or end goal. The telos of a knife, for instance, is to cut, and the telos of a shoe is to protect and cushion the foot. In each case, we can see that the telos of an object consists of its distinctive activity. According to Aristotle, the distinctive activity of humans is our capacity for rational thought. For that reason, the exercise of our rational powers is our telos, the highest good we can achieve. Aristotle lists five intellectual virtues with which we can exercise our rational powers. Prudence and art are both practical virtues and hence means to other ends. Of the other three, scientific knowledge and intuition both contribute to gaining a broad understanding of things, while wisdom rests in the contemplation we are capable of when we achieve this understanding. As such, the exercise of wisdom in rational contemplation seems to be the highest achievement of the intellectual virtues.

The conclusion that the telos, or end goal of being human, is rational contemplation may seem strange to modern readers, who have grown up in a world where nature is not seen in such teleological terms. We might agree that knives and shoes have distinctive activities, but only because they were created by humans to serve very specific purposes. The analogy of “distinctive activities” itself is at best tenuous, first because, unlike knives and shoes, we were not created for a specific purpose (so far as we know), and second because, depending on our point of view, we could identify all sorts of activities as distinctive to humans, from using tools to playing golf. Aristotle would argue that only our rationality is an essential feature of our humanity: we could be human even if we didn’t use tools or play golf, whereas we couldn’t be human without being rational. However, even if we accept this argument, we do not have to accept that we should concentrate our energies on rational contemplation simply because that is the “most human” use of our energies.