“Blackburn provides an elegant and accessible overview of Plato’s political and ethical theory as reflected in The Republic. . . . Blackburn discusses each idea in light of larger Platonic thought as well as the treatment these ideas have met throughout the past 2300 years. . . . It is balanced and popular in tone but does not gloss over nuances important to the understanding of the ideas expounded in the original text.” —Library Journal

“Blackburn’s analytical breakdown of Plato’s utopia, the transcendental and totalitarian overtones of which have annealed rapture and notoriety to The Republic, leads him to regard Plato as, if not always right, always asking the right questions about how to live. An animated and precise précis.” —Gilbert Taylor, Booklist

“A highly provocative and controversial work, Plato’s Republic: A Biography is an eye-opening work with particular relevance and importance for our post-9/11 world.” —Roy E. Perry, The Tennessean

They contain some of Plato’s most famous and radical doctrines, including the notorious defence of the philosopher-kings, and the famous Myth of the Cave. In so far as Republic has a metaphysical heartland, this is where it lies.

The leading character is of course Socrates. The historical Socrates had been executed by the Athenian democracy, in 399 BC, some twenty-five years before Republic was written, for the crime that he did not acknowledge duly the gods that the city acknowledged, invented new unacknowledged divinities, and corrupted the young. It is therefore a significant touch that the drama starts when Socrates piously goes down to the port of Piraeus, just outside the city of Athens, to pray, however, at a new festival, to an imported goddess. There is also a telling dramatic contrast with the dialogue The Symposium, which concerns the ascent of the soul, and begins with a journey up to the city rather than down from it. The first leitmotif, that of the uneasy relation between piety and criticism, between the customary usages of the city and the restless spirit of examination, is immediately established.

Not only is this the first leitmotif, but it sounds throughout Republic, throughout many of Plato’s other dialogues, and it echoes down the centuries to our own time. It confronts us with a choice. Is there nothing to living well except conformity to customary usage? Or is there also a possibility of a critical standpoint, a kind of external rationale to some particular set of rules or laws, such as, ideally, a proof that they deserve allegiance or that they alone provide a rational way of life for human beings? Is it a matter of simply conforming to whichever rules happen to be in place, in order to play the social game or is there something more, capable of underwriting the authority of those rules? Writing perhaps sixty or seventy years before Plato, the historian Herodotus noticed the overwhelming place of custom in people’s minds:

For if one were to offer men to choose out of all the customs in the world such as seemed to them the best, they would examine the whole number, and end by preferring their own; so convinced are they that their own usages far surpass those of all others’ Such is men’s wont herein; and Pindar was right, in my judgment, when he said, “Law is the king o’er all.”

Custom, or nomos in the sense Herodotus is quoting from the poet Pindar, embraces the rules of the community, the conventional system of norms enforced by the mutual watchfulness of a group. Jumping to the end of the seventeenth century, it is what John Locke called the “law of fashion” and is enforced by fear of reputation and ambition for esteem:

Thus the measure of what is everywhere called and esteemed virtue and vice is this approbation or dislike, praise or blame, which, by a secret and tacit consent, establishes itself in the several societies, tribes, and clubs of men in the world: whereby several actions come to find credit or disgrace amongst them, according to the judgment, maxims, or fashion of that place . . . But no man escapes the punishment of their censure and dislike, who offends against the fashion and opinion of the company he keeps, and would recommend himself to. Nor is there one of ten thousand, who is stiff and insensible enough, to bear up under the constant dislike and condemnation of his own club. He must be of a strange and unusual constitution, who can content himself to live in constant disgrace and disrepute with his own particular society.

Plato is well aware of the attractions of going no further than this. Indeed, one of the most eloquent set speeches in any dialogue, the so-called “great speech” from Protagoras, argues that we need nothing more. In it Protagoras (one of the disdained sophists) in effect gives an evolutionary psychology of morality, just by regarding it in this light, and showing how it enables men to cooperate and coordinate their actions, and thereby fulfil their mutual needs. The “law of fashion” is therefore not just something slightly shameful that we happen to go in for, as it were, out of a desire for popularity, or for fitting in with the gang. It is a natural and essential expression of human nature and human need. Our responsiveness to the law of fashion is a matter of internalizing the voices of others, as they would be poised to praise or condemn whatever we are doing. We absorb it, as it were by contagion, as a motive of our own, inclining us for or against a course of action. This responsiveness is a Darwinian adaptation, for human life with it will be more successful than life without it. In this area, we are all clubmen, all fashionistas.

The view that morality is in this sense the law of fashion is probably the dominant contemporary view of ethics, both among philosophers thinking of themselves as scientific in outlook, and especially amongst psychologists and evolutionary theorists. It can be served in different flavours. Locke, for instance, seemed to have in mind the way we absorb the opinion of other contemporaries. A particular variation of the type would be the touchy “man of honour,” whom we consider later. A variation might stress parental pressure, and more lurid Freudian variations might speculate about the psychological stresses involved in infancy as we resist having our wills moulded by outside forces. But whichever way we elaborate it, Plato regards it with suspicion and hostility.

This suspicion and hostility is shared, on different grounds, by classical liberalism. The fear is the tyranny of custom: the stifling, conservative, unthinking pressure of “the done thing” or “good form” or tradition. George Grote, the great Victorian historian and philosopher, a friend of Mill and liberal member of Parliament, talked with particular dislike of the rule of custom, Pindar’s nomos basileus or what he christened King Nomos, and whose tyranny was enforced by “the working of that spontaneous ever-present police by whom the authority of King Nomos is enforced in detail—a police not the less omnipotent because they wear no uniform, and carry no recognized title.”

But King Nomos has his defenders. In contemporary times “communitarians” stress the implicit wisdom in inherited folkways. They may, like the eighteenth-century conservative thinker and parliamentarian Edmund Burke, hold that freedom from King Nomos is neither desirable, nor possible. It is not possible because we are the kinds of animals already sketched. We only gain our self-identity through the gaze of others. And it is not desirable because a “rational” substitute—such as a scheme of civil society dreamed up on the drawing board—is infinitely less likely to work than one that has stood the test of time, insensibly and gradually adapting itself to the circumstances of living. We shall find that Plato is no fan of liberalism. But he cannot side with Burke, for he is himself centrally in the business of reason. His whole project can be seen as one of thinking morality through from first principles, and of dreaming up schemes on the drawing board.

The opposition between the hope for a “rational foundation” for ethics, and contentment with nothing beyond a foundation in custom and convention, is one of philosophy’s great divides. For many, it is painful and vertiginous to suppose that their cherished values stand on nothing firmer than custom and convention. It strips our favourite commitments of the dignities of reason, and substitutes the possibly invisible chains of culture: mere ideology, instead of rational law. But for others there is nothing sceptical or upsetting about confronting the fact that our ways are ultimately nothing more than our ways. In modern philosophy the idea that rules, including moral rules, simply reflect the way we happen to find it natural to go on, has been aided by massive authorities, including two giants of twentieth-century philosophy, W. V. Quine and Ludwig Wittgenstein. It fits well with the “postmodernist” picture of our minds as largely made up of (and made up by) the forces of convention, custom and, in the background, power.

Burke wrote in Britain at a time of relative political complacency and nervous conservatism, against the licence and upheaval witnessed in the French Revolution. Plato had a less comfortable historical bed to lie back upon: he was writing during a long period of Athenian upheaval, revolution, experiment, war and eventual decline. No wonder he thought that things needed designing on a more accurate plan than anything provided by the doodlings of history. He is certain that the reign of King Nomos is not good enough.

In Protagoras Socrates attempts to rebut the view with some rather unconvincing logic-chopping. In Book I of Republic the position is, as it were, spread out in two rich, conservative, self-satisfied tradesmen: Polemarchus and his father Cephalus. Socrates’s conversation with these two men is inconclusive, at best. In fact, it largely meanders around some uninteresting swordplay over whether a good man can ever harm anybody. It also shows Socrates’s irritating intellectualism: his tendency to think that if you cannot define something then you do not know what it is. He shows that these contented and conventional men cannot do a very good job of defining virtue. Their initial attempts are at best stumbling—but why should that be a problem? The law of fashion does not have to be articulated in order to work. Nobody can write down the rules of English grammar, but we can exert sufficient pressure on each other to conform to them. We can recognize what we cannot define.

Ideologically, the opposition between the rule of reason and the rule of custom is sharp enough. However, it can be softened when the conventionalist position is refined in various ways. First, conventions do not have to be accepted just as they are. There can be room for criticism and reflection, itself based on other aspects of convention and custom. In a familiar metaphor, we can stand on some planks of our boat, and repair others. Second, conventions and customs serve purposes, and those purposes assist their authority, and even provide a foundation, only of a different kind. Conventions assist needs and desires, some more important than others. The goals of coordinating with others, of finding peaceful solutions, of communicating, of finding ways of signalling reliability and trust, all enable recognizably human life to go forward. It is not belittling to the authority of promises, any more than it is to the authority of grammar, that it rests on filling such a need. Conventions arise to meet the needs determined by our natures. They are not arbitrary, or rather, it is simplistic and only half the picture to say that they are. It is not arbitrary that we need a convention to determine which side of the road to drive upon. It is only arbitrary how that need is met in detail: whether we find ourselves on the left or the right.

In Aristotle the stark opposition between reason and custom is moderated in another way. There is a threefold support for the idea of law: nature, custom and reason. Nature gives us the purely animal material with which custom or culture, and reason, have to work. Custom or ethos arises in the way we have imagined conformities arising, as we coordinate on things like rituals, or on patterns that enable us to cooperate. It transcends nature because it generates a social system of norms which is itself distinct from brute animal habit. Finally, laws, enacted by reason, shape custom. But they cannot exist without it: “in every case the lower faculty can exist apart from the higher, but the higher presupposes those below it.” As we shall see again in chapter 9, Plato’s tendency of mind is to sever the presupposition, thinking, in this area and others, that reason can float free of its earthly and earthy constraints in nature and custom. By contrast, the modern tendency is to think of this “reason” itself in terms of the political and rhetorical, the give and take of words in parliaments and courts, words which only custom and habit will make weigh with those who find themselves swayed by them (and then get called “good reasons” for one decision or another). King Nomos rules again.

Of course, Plato remains right to insist on space for criticism, and since he thinks that we have many fewer needs and very different natures than people normally suppose, he will continue to distrust the customs and conventions of any actual time and place. Plato supposes that King Nomos must not be allowed to rule, for disordered communities will have disordered folkways, and will encourage and enforce disordered norms as a result. He is certain that communities can be disordered: in Book VIII he gives a little taxonomy of the various ways this happens (see chapter 14). He scarcely confronts Polemarchus and Cephalus head-on in Book I. Dramatically, however, the inconclusive conversation sets the scene for the explosive entry of another modern figure, not the evolutionary psychologist or the communitarian, not a Wittgenstein or a Foucault with a subtle reinterpretation of the sources of authority, but the impatient, cynical amoralist, one of the first anti-heroes, the intransigent, cynical and sarcastic sophist Thrasymachus.