Thrasymachus and the Problem of Power That Judges Itself

*Charles Edward Andrew Lincoln IV

There is a familiar way of introducing separation of powers: place legislative, executive, and judicial power in three boxes and draw lines between them. That picture is useful as far as it goes, but it leaves out the question that matters most here. Who decides what a branch's authority means when the branch itself is the one pressing the claim? The difficulty is not only that powers may overlap. It is that an institution may come to define the scope, legality, and limits of its own action, and then pronounce on the dispute as well.

That question is older than modern constitutionalism. Near the beginning of Plato’s Republic, Thrasymachus gives Socrates a famously abrasive definition of justice. Justice, he says, is “the advantage of the stronger”. The rulers of each city make laws to suit themselves and then call obedience to those laws just. Read politically, the claim is unsettling because it collapses law into the interest of the authority that announces it. The stronger does not merely possess power. The stronger supplies the standard by which its own power is judged.

The separation of powers can be read as one answer to that problem. It does not assume that rulers will cease to have interests, ambitions, or blind spots. It asks instead how a constitutional order can keep any one institution from becoming author, interpreter, executor, and final judge of its own authority. That is a somewhat different way of approaching separation of powers from the familiar search for perfectly distinct functions. It is also useful in constitutional systems, including India, where the branches have never occupied watertight compartments.

The stronger sets the terms

Thrasymachus is sometimes remembered as little more than the man whom Socrates defeats in Book I. His argument is more interesting than that. He is describing a political danger that does not disappear merely because the government is democratic or because authority is written down in a constitution. If those who exercise power can also determine conclusively what counts as a lawful use of that power, legal form may do surprisingly little work.

Socrates begins with a simple objection: rulers sometimes misunderstand even their own interests. But the exchange soon moves beyond that point. He asks what it means to call ruling an art at all. Medicine is directed to the patient; in the same way, an art of governing cannot be defined only by what benefits the person who governs. One need not accept Plato’s political conclusions to see why this matters constitutionally. Holding an office is not the same thing as owning it. A grant of authority tells us who may act, but it does not by itself settle the purpose or limits of the power given.

That distinction carries over readily into constitutional design. Constitutions allocate authority, but they also arrange circumstances in which one institution has to give an account to another. Courts may test legislation against constitutional law; executive action usually rests on authority supplied elsewhere and may be reviewed; courts, in turn, do not acquire a general licence to legislate or administer simply because they can review those acts. Friction is built into the arrangement. The object is not to eliminate it, but to make it harder for the same public actor to formulate the rule, apply it, and decide conclusively whether it acted lawfully.

Montesquieu, Madison, and why division matters

Montesquieu’s account of the English constitution is often compressed into a rule against combining legislative, executive and judicial power. But the passage is really about the consequences of combination, especially the fear it creates. When the authority that writes a rule is also responsible for carrying it out, the citizen has reason to wonder whether the rule was framed for that very occasion. Add the power to judge the dispute, and there may be no institution outside that chain of decisions to which the citizen can appeal.

Madison’s contribution was to make the point less dependent on good behaviour. In Federalist No. 51, the problem is not solved by drawing boundaries on paper and trusting officials to respect them. The structure itself must give institutions reasons and means to resist encroachment. “Ambition” is made to counteract ambition because ambition cannot simply be wished out of political life. The argument is often presented as realism about human nature. It is equally realism about institutional judgment. No branch should be trusted as the sole constitutional accountant of its own power.

That is also why overlap is not necessarily a defect. The American Constitution itself contains vetoes, confirmations, impeachment, judicial review, appropriations, appointments and other points at which one institution becomes relevant to the work of another. As the United States Supreme Court has recognised, the Constitution combines separateness with interdependence. The important distinction is between participating in a constitutional check and taking over the function that is being checked. A system with no overlap would have little capacity for one institution to call another to account.

India and the problem of substitution

Indian constitutional law makes this distinction unusually visible. In Ram Jawaya Kapur v. State of Punjab, the Supreme Court rejected an absolutely rigid separation of powers while insisting that the functions of the different organs had been sufficiently differentiated. The Constitution did not require three sealed compartments, but neither did it contemplate one organ simply assuming functions that essentially belonged to another.

Two decades later, Indira Nehru Gandhi v. Raj Narain pushed the point further. The opinions resisted treating separation of powers as a “magic formula”. What mattered was the preservation of a constitutional balance and the restraint of concentrations of power that would upset it. That is a more useful starting point for a parliamentary constitution than asking whether India reproduces the American model. The better question is what kind of institutional crossing counts as a check and what kind becomes a substitution.

The Supreme Court’s 2025 advisory opinion on the powers of Governors and the President in relation to State Bills brings that distinction into a contemporary dispute. The Court concluded that judicially created “deemed assent” would amount to a substitution of the Court for a constitutional functionary. At the same time, it held that prolonged, unexplained and indefinite inaction by a Governor can invite limited judicial scrutiny and a direction to perform the constitutional function without dictating its substantive outcome.

I do not think the value of the 2025 opinion depends on agreeing with every line the Court drew. The more useful point is the difference it exposes between requiring a constitutional actor to do its job and doing the job in that actor’s place. A court may insist that a Governor act because the Constitution has assigned a duty to the Governor; it is another matter for the court to supply the constitutional decision itself. In difficult cases the two can sit uncomfortably close together. Both may be defended as checks, and both may be criticised as encroachments. Merely naming the three powers does not resolve that disagreement.

When a check becomes a substitution

I would put the distinction in practical terms. A constitutional check matters when it prevents an institution from being the only judge of a question about its own authority. Judicial review gives courts a role in testing executive and legislative action against law. Legislative oversight can require administrators to explain what they have done with delegated power. Assent requirements, hearings, confirmations, consultation and duties to give reasons work in related ways. They put another institutional voice into the process before one actor’s position becomes final.

The checking institution is not exempt from the same concern. Judicial review changes character if the court stops reviewing an executive choice and simply makes the choice itself. Administration can likewise become a form of lawmaking if the executive treats implementation as authority to dispense with legislation. And a legislature that resolves an individual dispute committed to adjudication has moved from making general law to judging a particular case. In each example the problem is not contact between branches. It is the displacement of one branch’s assigned task by another.

Seen this way, separation of powers is less a filing system for governmental functions than a rule about how public authority must be justified. It matters who acted, but it also matters what that official or institution can point to when challenged. Possession of power is not an answer in itself. The claim has to be connected to something the constitutional system recognises: text, procedure, precedent, appropriation, delegation, election, or another source that does not depend entirely on the actor's own say-so.

What Plato adds

In Gods, Judges, and Presidents, I came to this problem from a somewhat different direction, through legal history, political philosophy and older descriptions of divided social authority. Plato enters that discussion partly because the Republic later describes both city and soul in three parts. Yet for the narrower argument here, Book I is more revealing. Thrasymachus does not merely offer a cynical definition of justice. He raises the possibility that the language used to justify rule can itself be written by those who benefit from the rule.

A constitution cannot refute Thrasymachus by assuming that officials will be disinterested. It has to work with the less comfortable possibility that they will have ambitions, interests and institutional loyalties. The response is structural: decisions are divided, reasons are demanded, procedures interposed, and competing institutions are given opportunities to object. Those devices succeed unevenly, of course. Their common premise is more modest. Power should not become lawful merely because the person exercising it says that it is.

This helps explain why the principle remains relevant even where the old textbook picture has become untidy. Agencies may write rules, enforce them and decide disputes. Parliamentary government joins executive leadership to a legislative majority. Courts sometimes order remedies that have obvious policy consequences. Those facts make a perfectly clean functional map impossible, but they do not make the constitutional problem disappear. The question becomes whether there are still real institutional means of challenging an actor's account of the authority it claims.

Who gets the last word?

I therefore think the important feature of separated power is not geometric neatness. It is the refusal to let any institution make its own legal claim conclusive simply because it is the institution making it. Legislatures, executives and courts each exercise substantial power, but not the same kind of power, and none ordinarily writes every limit that applies to itself. That dependence on rules and institutions outside the immediate decision is part of what gives constitutional restraint practical content.

Thrasymachus imagined a political world in which the stronger could define justice to match its own advantage. A constitutional order cannot abolish the struggle for advantage, and it should not pretend to. It can, however, make that struggle pass through institutions that interrupt one another’s claims to finality. Separation of powers is one way of ensuring that power must still answer to something beyond itself.

*Charles Lincoln is currently a Ph.D. student at the University of Groningen studying international tax law in the field of business law, European law and tax law. He is also the author of "Gods, Judges, and Presidents: Trifunctional Archetypes in American Law and Government" where he interprets the U.S. Constitution through the mythic and psychological lens of Georges Dumézil's trifunctional framework - priest, warrior, and producer - linking it to thinkers like Homer, Plato, Freud, and Montesquieu.

The views expressed above are the author's alone and do not represent the beliefs of Pith & Substance: The CCAL Blog.