Book IX opens with a long and psychologically insightful description of the tyrannical man. The tyrannical man is a man ruled by his lawless desires. Lawless desires draw men toward all sorts of ghastly, shameless, criminal things. Socrates’ examples of lawless desires are the desires to sleep with one’s mother and to commit a foul murder. All of us have lawless desires, Socrates claims. The proof is that these desires occasionally come out at night, in our dreams, when the rational part of us is not on guard. But only the tyrannical man allows these desires to emerge in his waking hours.

The tyrannical man is the son of the democratic man. His father is not lawless, but he does indulge unnecessary desires. Just like the father, the son is exposed to drones, men with lawless desires. But whereas the father had his own oligarchic father’s thriftiness to pull him toward the middle road of democracy, this son, brought up on the democratic ethos, moves further toward lawlessness. The father and entire household try to win him back, but the ultimate triumph of the lawless is inevitable. The winning move of the drones is to implant an strong erotic love in the son: this love itself acts as a drone, and incites him to all manner of lawlessness. It makes him frenzied and mad, and banishes all sense of shame and moderation.

This man now lives for feasts, revelries, luxuries, and girlfriends. He spends so much money that he soon runs through all he has and needs to begin borrowing. Then, when no one will lend him any more, he resorts to deceit and force. We see him running the whole gamut of typically unjust acts in his insatiable need to quench his erotic lusts. First, he tries to get money out of his parents in all sorts of awful ways, then he starts breaking into houses, robbing temples, and finally committing murders. He has become while awake what he used to be only while asleep; he is living a nightmare. Erotic love drives this nightmare, keeping him lost in complete anarchy and lawlessness. He will dare to do anything to keep feeding the desires that erotic love produces. Soon he cannot trust anyone, and has no friends. The most decent parts of his soul are enslaved to the most vicious part, and so his entire soul is full of disorder and regret and is least free to do what it really wants. He is continually poor and unsatisfied, and he lives in fear.

After this frightening image of the tyrannical life, everyone is ready to agree that no life could be more wretched. Socrates, however, disagrees; there is one sort of life even worse than this one. That is the life of a man who is not only a private tyrant, but who becomes an actual political tyrant. To make us see that this life is even worse, he asks us to imagine what would happen if this private tyrant, along with his entire family and all his slaves, were moved to a deserted island. Without the law to protect him from his mistreated slaves, would not the tyrant fear terribly for his life and the life of his family? And what if he were then surrounded by people who did not look kindly on those who abused their slaves? Would he not then be in even greater danger? But this is just what it is like to be an actual tyrant. The tyrant is in continual danger of being killed in revenge for all the crimes he committed against his subjects, whom he has made into slaves. He cannot leave his own house for fear of all his enemies. He becomes a captive and lives in terror. The real tyrant is also in a better position to indulge all his awful whims and to sink further into degeneracy.

The tyrant, who is also the most unjust man, is the least happy. The aristocrat, the most just man, is the most happy. So we were wrong in Book II to conclude the opposite. This is the first of our proofs that it pays to be just.

In his lifetime, Plato had only ever seen tyrants driven by lust and greed. We might wonder if his diagnosis of the tyrannical psyche would have been the same if he had lived to see the totalitarian regimes of the twentieth century. His portrait of the tyrant is a brilliant and astute analysis of the Greek despot, but it seems less successful at capturing the psyche of a Hitler, a Stalin, or a Pol Pot. Were these men really driven by their appetites, or were they driven instead by reason gone horribly wrong? Plato never considers the possibility that reason itself can lead us toward evil, and perhaps he would try to maintain his position even in the face of recent history. He might argue that even in the case of these tyrants, the true driving force was a greed for money and power, and that reason, though playing a tremendous part in their deeds, was only instrumental reason, serving the ends of a nightmarish, lawless appetite. He might even be able to make a plausible case for this claim, pointing to the high honor and splendorous wealth these men achieved. Yet it is difficult to completely dismiss the suspicion that the real motivating force behind at least some of these regimes was a perverse idea and not an insatiable appetite.

Socrates has just provided us with one compelling reason to believe that justice is worthwhile: he has shown how much happier the just man is than the unjust. Now he provides us with a second argument for the conclusion that the just life is the most pleasant. There are three sorts of people in the world, goes the argument: truth-loving, honor-loving, and profit-loving. Each one of these people takes the greatest pleasure in whatever it is they most value and thinks that the best life is the life that involves the most of this pleasure. Yet among these, only one of them can be proved to be right. Only the philosopher is in a position to make this judgement, because only he has actually experienced all three pleasures. So we ought to believe the philosopher when he says that the pleasure of truth-seeking is the greatest pleasure. If the philosopher is right, the pleasure one gets from having a just soul (i.e., a soul aiming at fulfilling reason’s desires) is the best kind of pleasure. So, once again, we see that it does pay to be just.

The next argument also involves pleasures. Socrates argues that the pleasure of the philosopher is the only real pleasure. All other pleasures are actually relief from pain, not positive pleasure. Other pleasures are not real pleasures because other desires can never be completely satisfied. All we do is quench those yearnings tem-porarily, easing the pain of wanting. The philosophical desire can be completely fulfilled by grasping the Form of the Good.

Socrates now calculates that a king lives 729 times more pleasantly than a tyrant. This calculation is not supposed to be taken seriously, but is intended to emphasize that the just man is much happier than the unjust.

Finally, Socrates presents two refashioned portraits of the just and unjust man to replace the false portraits outlined in Book II. He asks us to envision that every human being with three animals inside of him: a multi-headed beast, a lion, and a human. If a man behaves unjustly, he tells us, then he is feeding the beast and the lion, making them strong, and starving and weakening the human being so that he gets dragged along wherever the others lead. He also fails to accustom the three parts to one another and leaves them as enemies. In the just person, the human has the most control. He takes care of the beast like a farm animal, feeding and domesticating the tame heads and preventing the savage ones from growing. He makes the lion his ally. The three parts are friends with each other. Socrates runs through various vices, such as licentiousness and cowardice, and shows how the three parts run amok to cause these vices.

Socrates declares that it is best for everyone to be ruled by divine reason, and while ideally such reason would be within oneself, the second best scenario is to have reason imposed from outside. This is the aim of having laws. The purpose of laws is not to harm people, as Thrasymachus claims, but to help them. Laws impose reason on those whose rational part is not strong enough to rule the soul.

Plato’s stated goal was to show that justice is worthwhile even in the absence of the rewards it might confer. In Book IX he argues that justice pays precisely because of such advantages. It will make for the most pleasurable life. If this is his argument, then he is failing to live up to his promises.

In fact, Plato made his argument for the worth of justice long before this, in Book VII. The true worth of justice, on this reading, stems from the connection of justice to the source of all worth in the universe, the Forms. Since the Forms are the ultimate good, and justice involves seeking, grasping, and imitating these, justice too is good and the just life is worthwhile. This is the interpretation that Aristotle favored, and contemporary philosophers such as Richard Kraut have attempted to revive this reading. Kraut explains this notion of worth in the following terms. For Plato, what makes a human life good, and a human value worthwhile, is its connection to an absolute external good, this external good being the Forms. He compares this Platonic point of view to the Christian worldview in which God is the greatest good, and bringing God into one’s life is what gives each life worth, and also to nineteenth century Romantic conceptions in which life only becomes worthwhile when it is not cut off from nature and the natural order. In all of these cases, the human good consists in relation to some higher, supreme good outside ourselves.

If knowledge of the form of the good is what makes the just life worthwhile, does anyone but the philosopher live a worthwhile life? If the Forms are the source of all worth and only the philosophers consort with the Forms, what can we say about everyone else? Do they have no chance at all to live a good life? Plato might respond to this question by stressing that any man can bring his soul toward the Forms to some extent by making sure that their soul is ordered and harmonious. In other words, by being just—by making sure that reason rules spirit and appetite—a man lives a worthwhile life even if he never grasps the Forms with his intellect.