The Laws of
Game Theory

The Law of Cheap Force

Why do cheap weapons beat expensive ones? The weaker party builds its strategy around cheap, expendable systems precisely because it cannot match expensive platforms — and the exchange rate favours it. A defence that spends millions to stop something that cost thousands is losing while winning.

The mechanism

Force comparison counts platforms. That assumes the contest is decided by whether you can defeat the incoming thing, and the answer is usually yes.

The right question is at what price, how many times, and how fast can each side replace what it spent. An interceptor takes months and a specialised supply chain. The thing it intercepted took days and used components sold to anyone. Both sides consume stock; only one can replace it at the rate of consumption.

Institutions make this worse. Procurement is rewarded for capability per unit on a decade-long cycle, measured against the most demanding threat rather than the most common one. It builds exquisite things slowly, which is correct for its incentives and wrong for the war it gets. Nobody's career advances by proposing the cheap thing.

A worked example

Set the two cost curves side by side over a year of exchanges.

The attacker launches items costing thousands, produced by industries that are not defence industries, at a rate limited by ordinary manufacturing. The defender intercepts with items costing hundreds of times more, produced by two suppliers, at a rate limited by a specialised chain.

Score the engagements: the defender wins nearly all of them. Score the economics: the defender is depleting a stock it cannot refill while the attacker is depleting a stock it can.

Then add the third party. Every other state is watching, and the exchange rate is now public. The lesson outlasts the conflict and is read by everyone who might face the same defender.

What would prove this wrong

A sustained campaign in which cheap attritable systems fail to impose disproportionate cost — because the defence found a kill mechanism at comparable marginal cost, or because the attacker's production proved more fragile than the defender's.

Where it comes from

Book One, chapter Game Theory #9: The US-Iran War. The arithmetic is worked through there on a conflict that was live at the time. The law is named in the second edition of that volume.

All 27 laws The method behind them

Last reviewed 31 July 2026