What is the virtue of a proportionate response?

The question is a line of screen dialogue, asked in 1999 by a fictional president of his Chairman of the Joint Chiefs, and it is worth taking seriously because of the answer it gets. The Chairman does not defend proportionality. He concedes the point — “It isn’t virtuous Mr. President. It’s all there is” — and the argument continues on entirely different ground. That concession is where this page starts, because a defence nobody offers cannot be the reason the practice survives.

Six defences are offered for proportionate response. Two of them turn out to be defending something other than what is under attack, three hold, and the sixth fails on its own terms — which is the one the position’s advocates are right about.

Two things are granted throughout. Adversaries who structure themselves around a known rule are real and documented, and a rule the adversary has already priced in is not functioning as a constraint on him. The question is what follows from that.

It is what the law requires

The most common defence collapses on inspection, because the legal rule and the popular one are not the same rule.

Proportionality in the law of armed conflict forbids an attack whose expected incidental civilian harm would be excessive relative to the concrete and direct military advantage anticipated. It compares harm to military gain. It does not compare harm to harm, it has never required matching a blow with a blow, and nothing in it obliges a state to answer a transmitter with a transmitter. The tit-for-tat convention — the thing the question is actually asking about — is a political and strategic practice, not a legal one.

What this establishes and does not. An argument against eye-for-eye symmetry does not touch the legal rule it is usually taken to attack, so the defence fails as stated and the attack misses as aimed. Both sides of the public argument are frequently discussing different objects. What survives is a narrower and harder question about the legal rule itself, which is whether “concrete and direct military advantage” can be assessed honestly against an adversary who has arranged the battlefield so that every advantage is expensive.

It protects civilians from an adversary hiding among them

The related claim is that proportionality is what stops a defender from being able to act at all when military capability is placed inside protected sites — hospitals, schools, mosques, tunnels beneath cemeteries. Documented cases of exactly this exist and are not in dispute here.

The rule does not do what this defence says it does. A protected site used for military purposes loses its protection; that is settled law and not a loophole. What remains is the proportionality calculation on incidental harm, which is a real constraint but a different one — and the party that placed the capability there bears responsibility for the consequences under the same body of law. Perfidy, which is often reached for at this point, is narrower than its colloquial use: it means killing, injuring or capturing an adversary by inviting his confidence that protection is owed and then betraying that confidence, not simply operating among civilians.

What this establishes and does not. The defence is confused about its own content, and so is the attack on it. The genuine problem is neither that the law forbids striking a mosque used as an armoury nor that proportionality is a suicide pact. It is that the calculation gets harder, slower and more contestable exactly where the adversary has made it so, which is a claim about friction rather than about prohibition.

It deters

This is the defence that fails, and the failure is the strongest ground the disproportion argument has.

A rule the adversary knows is a rule he can plan around. The drama makes the case better than most policy writing does: the four targets in the proportional package have been abandoned for four days, the satellites show it, and the strike will land on empty ground because the response was predictable enough to evacuate. “They did that, so we did this, it’s the cost of doing business, it’s been factored in.” The Chairman’s answer is “No sir, you’re right sir.” A response whose size and shape can be derived in advance from the provocation is not a deterrent; it is a tariff, and a tariff is something an adversary budgets for.

The same structure appears in the field. Where a rule of engagement is known and stable, a sufficiently adaptive opponent will reorganise around it — uniforms abandoned, capability moved beneath protected sites, operations timed to the constraint. At that point the rule has stopped deterring anything and has started allocating advantage.

What this establishes and does not. Predictability defeats deterrence, and the defence does not survive. It establishes that the practice of matching a blow with a blow buys less than it is assumed to buy. It does not establish that the alternative buys more, which is a separate question the remaining three defences answer.

It preserves the coalition

Here the defences begin to hold, and they hold on cost rather than on virtue.

The disproportionate option in the drama is priced out loud: thousands of civilian dead, a region’s medical supply and drinking water crippled, and then the bill — no allies, no Western coalition, no Britain, no Japan, no Congress. “You’ll have doled out a five thousand dollar punishment for a fifty buck crime.” The president is not talked out of it morally. He is shown the invoice, asks for a cigarette, and takes the proportional plan.

What this establishes and does not. This is a real constraint and it is not answerable by pointing out that the enemy is worse. It is contingent, though: it binds a state that needs allies and does not bind one that has decided it doesn’t, which is why the defence tends to be strongest exactly where a country’s strategic position is weakest.

It preserves the escalation ladder

The proportional response, in the Chairman’s phrasing, does not empty the options box for the future. A maximum response spends the maximum threat, and what remains afterwards is either repetition, which is no longer maximum, or nothing.

Escalation research supports the mechanism and adds a sharper finding. Attempts at escalation dominance produce reciprocal adaptation — opponents seek asymmetric strengths, prolong the conflict, and adopt precisely the behaviours that make the original problem worse. Human shielding is named in that literature as a predictable response to an adversary attempting dominance, which places it partly downstream of the strategy that cites it as justification.

What this establishes and does not. The defence holds and it is the most damaging one, because it turns the case against proportionality partly circular: the conduct offered as proof that restraint fails is in part produced by the attempt to escape restraint. That does not make the conduct acceptable and it does not mean restraint caused it outright. It means the causal story runs both directions and a page arguing only one of them is arguing half.

The rules protect our own people

The last defence is the one nobody in the public argument answers, and it is not moral in form. Reciprocity is why a captured soldier is supposed to be treated as a prisoner rather than as an object, and a state that has publicly announced it will answer an eye with a head has said something about what its own personnel can expect. The objection is usually made by former officers rather than by lawyers, which is worth noting: it is a force-protection argument wearing a legal coat.

What this establishes and does not. It holds, and it is narrower than it sounds. Reciprocity binds where the adversary is capable of reciprocating in kind and cares to, which describes states more than it describes the irregular opponents the argument is usually about. Against an adversary who was never going to observe the rule, the defence is weak; against the next war, which may be against someone else entirely, it is strong, and the precedent set does not stay in the theatre it was set in.

Where this leaves the question

The concession is genuine and it should be granted: proportionality is not a virtue. It is not morally superior to have answered a barracks with two transmitters, and the deterrence claim made on its behalf does not survive an adversary who can read the rule. Anyone defending the practice on those grounds is defending it badly.

What survives is entirely consequential. The practice persists because the alternative costs allies, spends the escalation ladder, and sets a precedent that outlives the conflict it was set for — and because the specific behaviour that most justifies abandoning it is partly a response to previous attempts at abandoning it.

Two observations complicate the frame further and belong on the record. Ratio retaliation has been tried as formal policy, most explicitly in a 1941 occupation order setting fifty to a hundred lives against one, and the officer who signed it was prosecuted at Nuremberg for that order among others. And the specific formula now circulating in English — a head for an eye — entered the 2026 exchange as an Iranian threat months before it was adopted as American policy, and its clearest theoretical defence was given by a hardline member of the Iranian parliament: “The defense doctrine of ‘an eye for an eye’ is wrong because it is not deterrent. The defense doctrine of ‘a head for an eye’ is correct because it is deterrent.” Whatever the argument is, it is not a Western insight about an adversary who only understands force. It is a doctrine both sides reach for, in the same words, in the same month.

Sources

• The West Wing, season 1 episode 3, “A Proportional Response”, written by Aaron Sorkin, aired NBC 6 October 1999. Transcript: westwingtranscripts.com; official podcast transcript, thewestwingweekly.com.
• Additional Protocol I to the Geneva Conventions, 8 June 1977, Articles 37, 44(3), 51(5)(b), 52. United Nations Treaty Series vol. 1125.
• Morgan et al., Dangerous Thresholds: Managing Escalation in the 21st Century, RAND MG-614-AF, 2008.
• Order for the suppression of communist insurrectionary movements in the occupied territories, 16 September 1941; Nuremberg document 389-PS.
• UN Fact-Finding Mission reporting on the Dahiya doctrine as declared by an Israeli Northern Command chief.
• Hamid Rasaei, member of the Iranian Majlis, 23 July 2026, Iran International.
• Full research bank, including the counter-case and the empirical record on reprisal and insurgency: 01 - Workbench/Proportional Response - Research Bank.md.