Aristotle begins by seeking to identify the best way of life. To do this, it’s necessary to identify the best good, or end—the thing people pursue for its own sake, not for the sake of anything else. He digresses to explain that Nicomachean Ethics will be a work of political science, the science which seeks the good of the city. He also points out that this work will “indicate the truth roughly and in outline,” not comprehensively.
Most people agree that happiness is the highest good, but they disagree about what it consists of. To understand the highest good, then, it’s necessary to understand the function of a human being. Aristotle describes this human function as “activity of the soul in accord with reason,” or, more particularly, with virtue.
There are virtues of thought and virtues of character. Virtues of character aren’t natural to us; they are achieved by means of habit. Because it’s the case that activities produce character, it’s important to figure out the right ways of acting which result in states of character—that is, actions which accord with reason. States tend to be ruined by excess or deficiency, just as too much or too little exercise can be harmful to bodily strength; the goal is to aim for the mean. This mean, or intermediate state, involves “having […] feelings at the right times, about the right things, toward the right people, for the right end, and in the right way.” In other words, being virtuous involves more than simply doing the right thing, but doing the right thing while in the appropriate, intermediate, state. Virtue has various preconditions; for example, one must deliberate and then decide on the virtuous end toward which one is aiming.
Aristotle discusses various specific virtues of character, and the extremes between which each is the mean, in detail. Bravery, for instance, is the state between rashness and cowardice. Temperance is a moderate appetite for fine things. A generous person avoids both wastefulness and ungenerosity. Magnificence involves spending worthy amounts on large purposes (such as temples for the gods), and magnanimity involves both being worthy of great honors and knowing one is worthy of such. A mild person is only angry at the appropriate times and to an appropriate extent. A friendly person is neither “ingratiating” nor cantankerous. Aristotle also discusses justice, which secures and maintains happiness for the political community. Because justice is concerned not only with the benefit of the individual, but with the benefit of society, it can be considered a kind of summary of the virtues.
Aristotle also discusses virtues of thought, which are those states that direct the soul toward truth. One of the most important is prudence, which is the ability to deliberate about what promotes good living—thus it’s the ability to reason correctly about virtue, not just in general, but with regard to particular situations.
One of the chief impediments to virtue is incontinence, or lack of self-restraint, which Aristotle addresses at length. People who lack self-restraint understand that it’s wrong to pursue a given pleasure, and they even deliberate and decide accordingly, but still act against their decision. The incontinent person can be trained through habituation to act according to virtue, whereas, say, the intemperate person is harder to correct because he believes it’s right to pursue his vice.
Aristotle discusses friendship at length because it involves virtue to a large degree. Friendship is also important to political science because it holds cities together. The most complete friendship occurs between people who are similar in virtue. Such friends desire good things for each other for their friend’s sake, not for any benefit or pleasure they might derive from one another. True friendship enables the cultivation of virtue. This happens especially when friends “live together,” sharing pleasures and pains in common.
Aristotle ultimately argues that because the supreme human virtue is understanding, the greatest happiness is achieved through study, or philosophical contemplation. But even though the contemplative life is the most desirable, the political life must be pursued for the sake of society’s good. He explains that most people don’t have a taste for virtue and that argument alone won’t reform their habits. This is why laws are needed—to introduce people to virtue in their youth and habituate them throughout their lives. Therefore, anyone who is concerned for the good of others and for society as a whole must study law and political systems, which Aristotle will address elsewhere.