The Republic by Plato, Part 2: Book I (Thrasymachus)

In this article I’ll look at the second half of Book I. This is where the Republic’s main antagonist enters the stage: Thrasymachus, unable to contain himself any longer, bursts into the conversation with his impatient, contemptuous rhetoric. When Socrates recovers from the shock, he cross-examines Thrasymachus in his customary style.

Recall the two central questions of the Republic:

1. What is justice?
2. Is the just life more personally beneficial than the unjust life? Or, is the just life happier than the unjust life?

Thrasymachus will have answers:

Thus he will offer a definition and a claim about the agent’s benefit. As noted, “the stronger” should be understood as the ruler.

I said Thrasymachus was the work’s main antagonist, but on a first read this can escape notice, because after Book I he doesn’t appear again and is hardly mentioned. This is because he is not the antagonist in the familiar dramatic sense but in a spiritual or conceptual sense: the rest of the work aims to defeat the position that Thrasymachus represents, and to do so more comprehensively than Socrates can manage in his direct examination of that position in Book I.

This is the meaning of the structure of the Republic, beginning with the back-and-forth of the Socratic elenchus in Book I, then progressing to an expansive and more positive theoretical exploration in what follows. The failure of Thrasymachus to sustain his position under Socrates’s examination is not enough to persuade the others that he is wrong, or rather—given that they probably do believe so intuitively—it is not enough to bring up to the level of consciously articulated knowledge precisely how he is wrong. For that, Socrates needs to present them with a coherent and convincing system against which Thrasymachus’s position shows up as false.

Which reminds me of Wittgenstein:

141. When we first begin to believe anything, what we believe is not a single proposition, it is a whole system of propositions. (Light dawns gradually over the whole.)

142. It is not single axioms that strike me as obvious, it is a system in which consequences and premises give one another mutual support.

— On Certainty

Plato knows this, which is why, after Book I, he goes to the effort of carefully painting a picture of his entire conception of the city and the soul.

Who is Thrasymachus?

It helps to know who he is, and what he represents for Plato. Thrasymachus was a historical figure, well-known in his time even apart from his immortalization by Plato. He was one of the sophists, a class of freelance intellectuals—professional instructors in public speaking and argument.

From the point of view of Socrates, the sophists love the sound of their own voices, crafting artfully persuasive or domineering speeches rather than joining a communal effort to search for truth. He sees them as seeking, not truth at all, but victory—perhaps inevitable, considering they’re doing it for money.

Crucially, according to Socrates and Plato, these intellectual vices are fertile ground for the growth of moral nihilism and relativism. It is no coincidence that Thrasymachus, whose use of argument and speech in his everyday life is merely instrumental, also believes that virtues such as justice are merely instrumental, a cynical means to the ends of power and wealth. Representing a mercenary intellectual tradition, Thrasymachus naturally frames justice as mercenary too.

So he is portrayed as aggressive, contemptuous, eager to speak more than to listen, impatient with the give-and-take of enquiry—and when the argument turns against him, he effectively throws his toys out of the pram, petulantly withdrawing instead of openly yielding according to the dictates of reason.

An admirer of tyrants, he is himself the intellectual tyrant of the Republic. As such, he has a soul which is disordered, like the society ruled by a tyrant, and Socrates will set out this parallel in depth later on.

Summary

A preliminary summary will help. The second half of Book I goes like this:

1. Thrasymachus demands to hear Socrates’s definition of justice. Socrates and the others persuade him to give his own definition (partly by paying him)
2. Thrasymachus claims that justice is what serves the interests of the ruling power. 338b
3. He argues for this from 338d to 341a.
4. Socrates, by elenchus, challenges his definition and shows him that ruling, considered as a craft, aims at the good of the ruled rather than the ruler. (341c-342e)
5. Thrasymachus’s long speech, offering alternative support for his claim. This goes from 343a to 344c.
6. Socrates elaborates on his argument that crafts aim at the good of their subject rather than the good of the craft’s practitioner, arguing that wage-earning is external to other crafts. (345b to 347a)
7. Glaucon interrupts and thereafter Socrates turns away from definition as such and proceeds to challenge Thrasymachus’s claim about the supposed benefit and happiness of injustice. (347a-348b)
8. First he shows that a just person is good and wise, and an unjust one ignorant and bad. This causes Thrasymachus to blush. (348b-350d)
9. Socrates argues that collective success and strength in action require justice. (350d-352d)
10. Socrates continues, showing that not only is injustice ignorant and bad, but it doesn’t bring happiness or profit either. (352d-354c)

1. Thrasymachus is introduced

By the time we get halfway through Book I, Socrates has revealed the defectiveness of the definitions of justice offered by Cephalus and then his son Polemarchus:

SOCRATES: All right. Since it has become apparent, then, that neither justice nor the just consists in benefiting friends and harming enemies, what else should one say it is?

This is when Thrasymachus is introduced, in dramatic fashion:

Now, while we were speaking, Thrasymachus had tried many times to take over the discussion but was restrained by those sitting near him, who wanted to hear our argument to the end. When we paused after what I had just said, however, he could not keep quiet any longer: crouched up like a wild beast about to spring, he hurled himself at us as if to tear us to pieces. Polemarchus and I were frightened and flustered as he roared into our midst.

[336a]

This initiates Plato’s portrayal of Thrasymachus the sophist as a dangerous character, and dangerous in several ways:

• In his arrogant and confrontational manner.
• In his mercenary approach to discussion—as we’ll see, he refuses to give his account of justice until the others have committed to paying him.
• In the intellectual attitude he represents, that of cynical nihilism and relativism with regard to justice and truth.

He roars into their midst with this:

What nonsense you two have been talking all this time, Socrates! Why do you act like naïve people, giving way to one another? If you really want to know what justice is, don’t just ask questions and then indulge your love of honor by refuting the answers. You know very well it is easier to ask questions than to answer them. Give an answer yourself and tell us what you say the just is.

[336b]

Plato here draws our attention to a fundamental difference in philosophical approach. Socrates favours questions and dialogue, whereas Thrasymachus favours opinion and speechifying.

Irony

Socrates’s response prompts Thrasymachus to accuse him of being ironic, and this is an accusation that’s been levelled at Socrates ever since, right up to the present day. And it’s easy to see why. Phrases such as “Don’t be too hard on us,” “my friend,” and “you clever people” seem ironic in the extreme. However, his emphasis on the seriousness and value of the search for justice is sincere. Thus we have ironic tone, serious intent.

But what is the point of the ironic tone? I think it’s a subtle combination of provocation and defence, provoking Thrasymachus at the same time as defending against his violence—Socrates faces up to him without, however, meeting him on his own ground, i.e., with violence.

And he carries on in this mode:

That is because you are a wise fellow, Thrasymachus.

[337a]

2. Thrasymachus’s definition

Thrasymachus continues to demand Socrates’s definition of justice until Socrates turns it around, [337c - 338a]. And—once he has received assurances that he will be paid for it (Socrates himself having no money)—Thrasymachus obliges:

THRASYMACHUS: Listen, then. I say justice is nothing other than what is advantageous for the stronger. Well, why don’t you praise me? No, you are unwilling.

[338b]

Persuasion

In what follows, we can extract formal arguments from what Thrasymachus says in defence of his definition, but it’s important to see that Thrasymachus is engaging in persuasion more than simply in argument. He wants to have his view prevail.

But Thrasymachus is not a simple villain. As I suggested in the first article, Plato’s oppositions are rarely strict dichotomies. Persuasion and argument are not mutually exclusive activities: to advance an argument is typically also to seek its acceptance. Wanting to persuade others is not inimical to truth-seeking, and Plato has no reason to deny this. What distinguishes Thrasymachus is not merely that he seeks to persuade, but that he relies on rhetoric and force rather than reason to do so.

Whatever we might think of Thrasymachus, this complex relation between argument and persuasion is one that Plato wants us to think about.

3. Thrasymachus’s first attempt

Under pressure from Socrates, at [338d] he clarifies that “the stronger” is the ruling power, whether in an aristocracy, a democracy, or a tyranny. But Socrates shows that Thrasymachus’s account is internally contradictory:

SOCRATES: And are the rulers in each city infallible, or are they liable to error?

THRASYMACHUS: No doubt, they are liable to error.

[…]

SOCRATES: And whatever laws the rulers make must be obeyed by their subjects, and that is what is just?

THRASYMACHUS: Of course.

SOCRATES: According to your account, then, it isn’t only just to do what is advantageous for the stronger, but also the opposite: what is not advantageous.

[339c]

Given that rulers are sometimes in error about what is of advantage to them, and given that their subjects, in obeying the law, are acting justly, it follows that the subjects will sometimes act to the disadvantage of the ruler. The assertion that justice is lawfulness is one that Socrates will question later on, but at this point he is going along with Thrasymachus, who presupposes it.

Clitophon intervenes to save Thrasymachus:

CLITOPHON: But what he meant by what is advantageous for the stronger is what the stronger believes to be advantageous for him. That is what he maintained the weaker must do, and that is what he maintained is what is just.

[340b]

But Thrasymachus rejects this solution. Since accepting it would save his account from Socrates’s immediate objection, we have to ask why.

If Thrasymachus were to agree that acting justly is doing what the ruler believes to be to their advantage, then his position would be a subjectivist one: justice is whatever the ruler thinks is good. Thrasymachus may be a cynic, but he wants to say more than this. He wants to make a structural point, that justice is objectively the ruler’s benefit, that ruling just is to exploit everyone else to one’s advantage, and that this is wise. The account is of a polis which is operated to achieve this, with a normative force as to what one should do. The position that justice is merely what the ruler believes is advantageous is too weak to achieve this.

Worse, Clitophon’s solution—amounting to an observation that rulers pass laws to benefit themselves, and name this justice—invites the idea that although the rulers give their exploitative systems the name of justice, it is actually not justice at all. And if Thrasymachus accepted that, he would completely undermine his own position, because he would no longer be giving an account of justice at all, but only how certain people use the term.

He wants to say that injustice is the correct route to happiness, that the wisest ruler is the most unjust. If justice is what a ruler says it is, and this ruler says that his exploitative laws are just, then he is behaving justly in enacting them. This deflationary, or cynical, or somewhat Nietzschean view, is not what Thrasymachus is arguing for. He is positively immoralist, standing up for injustice. The clearest case is a tyranny. If you are not the tyrant, acting justly by obeying the laws is unwise and will not benefit you; if you are the tyrant, acting justly by acting to the advantage of the people will again not benefit you.

Since Clitophon effectively identifies justice with conformity to the ruler’s laws, whether or not they benefit the ruler, he is implying a kind of legalism. In contrast, Thrasymachus is presenting a radical theory about power.

• Legalism (Clitophon): Justice is whatever the law says.
• Theory of power (Thrasymachus): Justice is the system by which the stronger secure their advantage, requiring those who act justly to act for the advantage of others rather than themselves.

Note that Thrasymachus’s theory does not claim that, in maintaining this system of justice, rulers are thereby acting justly—a view which would align with conventionalism (justice is whatever the rulers say it is). It’s precisely the opposite.

To support this position, Thrasymachus must hold that a ruler never errs insofar as he is a ruler, that when he errs he is not properly doing his job of ruling. Or in classically philosophical terms, a ruler qua ruler necessarily acts to his own advantage, since that is what ruling is.

Thrasymachus states this explicitly [340c-340e] and explains himself according to the scheme, already introduced by Socrates in his exchange with Polemarchus, in which justice is treated as a craft, one among many others such as medicine or accountancy.

He then distinguishes between ordinary and precise usage. We are to understand that when he earlier agreed that rulers are fallible [339c], he meant it in the ordinary sense. In the precise sense of “ruler,” rulers never err as to what benefits them.

He concludes:

THRASYMACHUS: […] No craftsman, wise man, or ruler makes an error at the moment when he is ruling, even though everyone will say that a physician or a ruler makes errors. It is in this loose way that you must also take the answer I gave just now. But the most precise answer is this: a ruler, to the extent that he is a ruler, never makes errors and unerringly decrees what is best for himself, and that is what his subject must do. Thus, as I said from the first, it is just to do what is advantageous for the stronger.

[340e]

4. Socrates’s examination begins

Socrates begins his examination of Thrasymachus’s position:

SOCRATES: […] Tell me: is a doctor—in the precise sense, the one you mentioned before—a moneymaker or someone who treats the sick?

[341c]

He then argues to the conclusion that in the exercise of any craft, the practitioner aims not at his own benefit, but at the benefit of that which the craft is concerned with. A doctor in the precise sense aims at the benefit of his patients, not of himself. A sea captain in the precise sense aims at the benefit of his sailors and “his subject” [342e], i.e., the sailing of ships.

We thus see a consequence of Thrasymachus’s distinction between ordinary and precise language that ultimately undermines his own position. Socrates has met Thrasymachus’s view head-on and shown that, given the precise framing that Thrasymachus has himself put forward, its implications contradict the original definition. A ruler qua ruler aims at the benefit of that which he rules over, i.e., the people and the polis.

To get there Socrates has accepted a few of Thrasymachus’s premises, for the sake of argument. It is not important at this stage to work out whether Socrates really accepts them—that justice is a craft like others, and that we can distinguish between ordinary and precise usage in the way suggested. His aim at this point is just to reveal that Thrasymachus’s view has internal inconsistencies. This is a textbook example of elenchus.

Notice that Thrasymachus has been made to agree to every step along the way. From here, he cannot easily escape. As we’ll see, he reacts with contemptuous ridicule and rhetoric.

5. Thrasymachus’s second attempt [343a to 344c]

This is delivered in the form of a long speech, which he kicks off with insulting accusations of naivety. Plato is signalling a lack of intellectual honesty or seriousness in the sophistic approach: Thrasymachus is trying to steamroll Socrates and the others into conceding, partly with an appeal to common sense. He says it’s naive to think that a shepherd aims at the benefit of his sheep rather than at his own benefit. Obviously, aiming for the benefit of your sheep is (normally) a short-term means to a self-interested end.

I find much of the secondary literature on this topic to be quite alienating. Some Plato scholars tend to emphasize Thrasymachus’s bad behaviour—insults, rhetoric, speechifying, and so on—and seem to assume that his speech is entirely illegitimate. But I surely wasn’t alone in cheering him on, relieved that someone is willing to question Socrates’s abstract, logical trickery, instead bringing things down to earth. So I was on Thrasymachus’s side, and thought that Socrates deserved the insults.

Whether or not this implies that I possess a disordered soul, Thrasymachus is surely right to question the notion that a practitioner of a craft never aims at their own benefit. That would fly in the face of common sense; the suspicion is raised that Socrates has used some sleight of hand to carry his argument. I’ll explore that below.

It’s in this speech that Thrasymachus forces a shift in the discussion from definition to evaluation, since he collapses the distinction. In a speech meant to address the question as to what justice is, he culminates with the following:

So you see, Socrates, injustice, if it is on a large enough scale, is stronger, freer, and more masterful than justice. And, as I said from the beginning, justice is what is advantageous for the stronger, while injustice is profitable and advantageous for oneself.

[344c]

This wraps up the question of the definition of justice with the question as to whether justice brings advantage and happiness. As we will see, Socrates takes this as a cue to move away from the issue of definition as such, but not before he develops his position on craft to show that Thrasymachus has not really addressed it.

6. Socrates’s examination continues

At [345b] Socrates resumes the craft argument, now introducing the crucial distinction between a craft and wage-earning, which is thus considered to be a separate craft. Since wage-earning is external to medicine, shepherding, and ruling, personal benefit cannot define those crafts. Applied to ruling, this yields the conclusion that a ruler qua ruler acts for the benefit of the ruled, even if ruling also brings advantage to the ruler in some other capacity. This line of argument lasts up to Glaucon’s interruption at [347a].

With these clarifications Socrates is showing that in his grand speech Thrasymachus has failed to properly defend his definition against Socrates’s criticisms. What he has really done is just repeat himself.

It will help to see how their positions differ.

Two concepts of craft

Was I being unfair when I accused Socrates of sleight of hand? Probably. But at the very least, he has been assuming a controversial concept of craft, one that makes his conclusions inevitable. Note that craft is a translation of the Greek term techne, which refers to skillful practice and specialized knowledge.

Socrates and Thrasymachus hold competing conceptions of craft. They agree that each techne has its own characteristic ergon (function), but they disagree on how that function operates, such that for Socrates, the intrinsic telos of the craft defines that function.

So by calling Socrates’s conception “functional”, I mean that for Socrates the function of a craft determines its norm of correctness from within the activity itself; by contrast, Thrasymachus treats a craft as a means whose function is fixed only by its effectiveness in achieving independently specified ends.

The functional concept (Socrates):

• The specialized means of a craft are directed toward the benefit of those the craft is exercised over.
• The practitioner’s advantage is a further, external end, not the defining one.

So medicine is for health/the patients, shepherding is for the sheep, and ruling, if it is a craft, is for the good of the ruled. To say this is functional is to say that the benefit of those the craft is exercised over (sheep or citizens) is not a means to a further end but defines the activity itself.

The instrumental concept (Thrasymachus):

• The specialized means of a craft are directed toward the practitioner’s own advantage.
• Any benefit to others is a means to that end.

So medicine is for the doctor’s own benefit, shepherding is for the shepherd’s profit. To say this is instrumental is to say that the benefit of those the craft is exercised over (sheep or citizens) is a means to a further end.

The latter conception is quite an intuitive one, certainly in the modern world. The trouble is, Thrasymachus isn’t just talking about shepherding: he’s also saying that ruling is necessarily for the ruler’s advantage and that justice names the successful operation of these arrangements, that is, the obedience of the people. If we are accepting that ruling and justice are crafts, i.e., activities with their own specialist knowledge and techniques, we have to say that they are basically self-interested, and we end up with a view that is either entirely immoralist—if we side with the ruler—or entirely pessimistic and cynical.

If we’re not comfortable endorsing these views, we need to be patient. Socrates will show us another way, which will require an abandonment of the assumption that justice is a craft.

7. Glaucon interrupts

Glaucon’s interruption at [347a] prompts Socrates to clarify that the benefit to oneself that goes along with the practice of a craft, which is not intrinsic to the craft itself, may take a negative form in the case of ruling. Since one rules not for oneself but for the ruled, some sort of incentive or compulsion is normally required to make a person rule, and this may take the form of a penalty for refusal.

He begins [347a] with an appeal to a commonly held ethical intuition, that those who love money and honour are rightly despised. This functions to further support the position that good people do not rule for their own benefit:

In a city of good men, if it came into being, the citizens would fight in order not to rule, just as they now do in order to rule. There it would be quite clear that anyone who is really and truly a ruler does not naturally seek what is advantageous for himself, but what is so for his subject. As a result, anyone with any sense would prefer to be benefited by another than to go to the trouble of benefiting him.

[347d]

Socrates here implicitly accepts something that Thrasymachus relies on in his arguments, namely that actually existing rulers often rule for their own benefit. So he is careful to say that good people won’t be willing to rule. Now, the word good here relates more to excellence and wisdom with regard to the function of a craft than to what we understand as moral goodness. So what Socrates means is that those who are willing to rule, with their own benefit in mind, are misunderstanding the function of ruling, namely to secure the benefit of the ruled. The good person understands this. Those who rule for selfish reasons are not in fact ruling in the precise sense; or in the imprecise sense, they are simply bad at ruling.

But then, a shift takes place:

So I cannot at all agree with Thrasymachus that justice is what is advantageous for the stronger. But we will look further into that another time. What Thrasymachus is now saying—that the life of an unjust person is better than that of a just one—seems to be of far greater importance.

[347d]

Here Socrates abandons the issue of definition and turns the discussion towards benefit and happiness, a move already anticipated in Thrasymachus’s earlier speech. It is here that the exchange definitively shifts from a primarily definitional to an evaluative approach. Socrates recognizes that this shift is unavoidable, not only because his arguments are unlikely to be accepted by Thrasymachus, but because the disagreement just cannot be resolved at the level of definition alone. In a certain sense Socrates and Thrasymachus have incommensurable views, and it’s at this point that Socrates decides to address this, or perhaps just to lay it out for everyone to see.

The sense in which their views are incommensurable is that they are each starting out from a different framework of underlying values which divergently determine how they will approach the question as to what justice is. This definitional question might seem the most fundamental one, but in fact it is dependent on prior political and ethical presuppositions and commitments.

Glaucon agrees [347e] that the life of a just person is more profitable than the life of an unjust person, but he believes this only intuitively—what he wants is understanding.

Socrates starts afresh at [348a] by discarding Thrasymachus’s method. He asks if he should proceed by making a big speech in response to Thrasymachus’s, and to continue trading speeches until a jury has to decide the case—or if the group should investigate the question together, seeking agreement along the way. Of course Glaucon opts for the latter, and Socrates launches into an elenchus once again.

8. Socrates’s examination changes direction

It transpires that Thrasymachus believes that injustice, rather than justice, is a virtue. Socrates notes how radical this claim is:

If you had declared that injustice is more profitable, but agreed that it is a vice or shameful, as some others do, we could be discussing the matter on the basis of conventional views.

[348e]

Thrasymachus does not take the conventional route, in the same way that he did not accept Clitophon’s solution: he avoids saying anything that might suggest the claim that justice is whatever the ruler says it is. If he agreed that injustice was a shameful vice, that would fit with the ruler’s attempt to cloak their actions in the appearance of justice, and the ruler would at best (at worst?) be a successful scoundrel. But Thrasymachus wants to uphold the tyrant as the most excellent of men, and therefore the most virtuous (remembering that arete denotes excellence with regard to function, not moral rectitude). He is very deliberately upturning the concept of virtue, such that injustice is not something to be ashamed of in the first place.

Socrates then argues to the conclusion (at [350c]) that “A just person has turned out to be good and wise, then, and an unjust one ignorant and bad.”

His argument can be set out as follows:

My first thought was, why does Thrasymachus accept premise 1? This is the crucial premise; once he accepts it, everything else follows fairly uncontroversially.

The answer is to see how difficult it really is to deny it. Premise 1 is more obvious than it seems. We might think that many if not all practitioners are competitive, that they want to be the best at their craft—that’s certainly how I reacted to it. But Socrates means something rather different. He means that every practitioner of a craft wants to do the job right. There is a proper, effective way to fulfil the function of a craft, and that is what every practitioner qua practitioner aims to do. For example, two doctors who know the case of a patient will carry out the same treatment. If they know what to do to fulfil the function of their craft, that is what they will want to do, which is the same as what every other wise and skillful doctor will do. Thus, what counts is doing it right, not outdoing the other.

The way in which people wish to outdo others relates to the external ends of money and honour, not to the craft itself.

This was all widely shared in ancient Greece, and even Thrasymachus won’t deny it, especially since he presents injustice and tyranny as forms of superior intelligence and mastery.

But that lets Socrates off the hook. Many scholars see an equivocation here, aligning perfectly with the intuitive objection I’ve just dealt with. Just as in modern English, the Greek for “outdo” (pleonektein) can mean (a) deviating from the correct standard, e.g., the right treatment for the patient, or (b) gaining advantage. This allows Socrates to say that injustice, more than being morally bad, is actually a form of incompetence in the area of intelligence and mastery.

So sense (a) relates to crafts, and sense (b) relates to moral action in life. Socrates’s connection of the two comes close to a conflation. Whether this is justified is not yet clear.

That aside, there are other problems with Socrates’s argument, and one in particular is very important: what right does he have to assume that injustice has objective standards as crafts do? Put differently, what right does he have to assume there is a correct way to live, analogous to the correct way to heal a broken leg?

And I think the answer, as often in Book I, is that we have to wait and see. It is preparation for the rest of the work, which will aim not only to show what justice is but also to show that it has objective standards and that it is better to be just than unjust.

When Thrasymachus is finally led to Socrates’s conclusion that “A just person has turned out to be good and wise, then, and an unjust one ignorant and bad,” he blushes [350d]. He is no more convinced than we are, but he is embarrassed at being defeated in dialectic—which is not to say he has been refuted or converted.

9. An argument from cooperation

Thrasymachus behaves petulantly from this point. His position has not actually been refuted, but as interlocutor and dramatic character he has been defeated, shamed by Socrates. Thus Plato has shown us that the latter’s equanimity and spirit of innocent enquiry are sufficient to overcome aggression and bluster.

Socrates first addresses the idea that “injustice is stronger and more powerful than justice,” by arguing that at the very least, many people acting together to achieve unjust aims have to act justly among themselves, otherwise they won’t achieve anything. This is because injustice within a collective, such as a city, causes infighting and hatred between its members. He extends this to the individual: internal strife will result from injustice and render the individual ineffective, an enemy of himself.

This is rather weak as an argument in favour of justice and it seems clear that it’s meant to be understood merely as secondary support. It’s weak because it shows only that justice is instrumentally better at achieving an aim, not that it is intrinsically better. It shows that justice is better than injustice at some level, not that it is better or more advantageous in and of itself.

10. Socrates concludes

He then returns to the concept of function (ergon). First he sets out the basic shared understanding of function: each thing has virtues that enable the thing’s characteristic function to be performed well. After illustrating this with various everyday examples, he introduces the soul [353d]: a function of the soul is living. So what is the virtue that enables the function of living to be performed well? It is justice, and injustice is a vice.

It follows that the just person lives well, and the unjust person lives badly. Furthermore, since living well is happiness and living badly is unhappiness, the just person is happy and the unjust person is unhappy [354a].

The thing that sticks out is the premise that justice is the virtue of the soul that enables the function of living to be performed well.

SOCRATES: Now, didn’t we agree that justice is a soul’s virtue and injustice its vice?

THRASYMACHUS: Yes, we did agree.

[353e]

My reaction was “Wait—when did they agree to that?” What Socrates concluded at [350c] was that “the just person is wise and good, and the unjust person ignorant and bad” (where “good” can be understood as excellent). This association between justice and wisdom/excellence doesn’t establish that justice is the excellence that allows the soul to function well.

So Thrasymachus in fact never did agree to this. At this point he is in a sulk, agreeing to everything Socrates says in a somewhat sarcastic or reluctant manner.

The thing is, the whole argument hinges on this premise, so it looks like begging the question. Thrasymachus doesn’t really agree with it, and nobody else would agree with it unless they already agreed with the conclusion. Whether it’s truly question-begging in context or not, at the very least we can say that Socrates has not shown this premise to be true, and this is part of the reason that the argument is unconvincing.

Most scholars agree that Plato is aware of this. Even aside from the insufficiently supported premise, Plato signals that the argument might be unconvincing by having Socrates’s interlocutor, Thrasymachus, assent to everything just to get it over with. It feels far too easy.

In any case, none of this means that Plato disagrees with the argument, only that he knows there is work to be done to support that crucial premise. And that’s what he will attempt to do for the rest of the Republic.

Is Thrasymachus incoherent?

Some scholars have puzzled over the supposed inconsistency of Thrasymachus’s stated views:

1. Justice is the advantage of the stronger.
2. Justice is obedience to the laws.
3. Justice is the advantage of the other.

On the surface, it looks like these cannot all be true. If I am the stronger, then according to (1) justice is to my advantage, but according to (3) it is to the other’s advantage. This objection has always struck me as pedantic, and I don’t get any sense of incoherence when I read Book I, which suggests to me that Plato did not intend to portray Thrasymachus as incoherent.

The key to unlock this problem is to see that statement (1) is indexical—indexed to (or relative to) the agent’s standpoint, where the agent is assumed not to be the ruler. It is about what is best from your own point of view as a regular citizen acting justly, so the stronger means the one who is stronger than you. So, to act justly is to act to the advantage of whoever is more powerful than you.

But in statement (3), the agent might be anyone, including the ruler—so the other can be either too. As one of the ruled, you are just when acting to benefit the ruler; as the ruler, you would be just if acting to benefit the people. Thrasymachus will criticize acting justly in both cases, and will praise tyrants as exercising the most complete injustice.

The thing is, the three statements are not presented in the text as standalone definitions. Setting them out in a list, as above, can be misleading. They emerge organically in conversation as different ways of explaining the same social phenomenon, and together they amount to a sociological theory. With this bleak sociology, Thrasymachus is more dangerous than confused, at least from Plato’s point of view.

Notes

Top image: Roman mosaic from Pompeii

• Plato, Republic, translated by C. D. C. Reeve, Hackett, 2004
• Annas, Julia. An Introduction to Plato’s Republic, Oxford: Clarendon Press, 1981
• McAleer, Sean. Plato’s Republic: An Introduction, Cambridge, UK: Open Book Publishers, 2020, https://doi.org/10.11647/OBP.0229
• Ludlam, Ivor. Plato’s Republic as a Philosophical Drama on Doing Well. Lexington Books, 2014.
• Thrasymachus, Internet Encyclopedia of Philosophy. https://iep.utm.edu/thrasymachus/