Shape 10
The Ultimatum
One side proposes a split; the other can only accept or destroy the whole thing.
This is the cleanest demonstration in the subject that payoff is not money. The formal prediction — offer the minimum, have it accepted — fails in every population studied, with modal offers around 40–50% and low offers rejected roughly half the time. The correct reading is not that equilibrium reasoning fails but that the utility function was wrong: fairness, status and the cost of accepting an insult are genuine payoff terms with measurable magnitudes.
- How it feels
- One side sets the terms and the other can only accept or wreck it.
- The refusal option hurts the refuser too, and is still on the table.
- The words 'on principle' appear, about a sum that seems small.
- Somebody is calculating the offer purely on what the other side can bear.
- Who is playing
- The proposer and the responder — plus, crucially, everyone who will hear how this went. Refusal is much more common in public, because the reputational payoff is real and is missing from the private version.
- Where it lands
- Textbook: the smallest possible offer, accepted. Reality: offers near half, and low offers refused about half the time at real cost to the refuser.
- What moves it
If you are the proposer, price the insult — an offer optimised purely on what they can bear is frequently rejected and always remembered. If you are the responder, decide in advance what you are buying by refusing, so that it is a purchase rather than a reflex.
Not to be confused with
Nearly every misread in practice is a shape mistaken for its neighbour — and each of those mistakes points you at the wrong fix.
Bargaining
Can the second side counter-offer? If yes it is bargaining, and the power is far more symmetric than it looks.
Chicken
Does the destruction hurt both, or mostly the proposer? If refusal is mutually catastrophic you are in chicken, and commitment tactics apply.
Where you have already met it
Work and Careers
A final salary offer calculated on what the candidate will tolerate. It is often accepted and it is always remembered.
Law and Courts
A settlement offer pitched just above the cost of continuing. Refusals here are frequently about dignity and are entirely rational.
Markets and Money
A dominant buyer's terms to a small supplier. The formal analysis says accept; the observed behaviour includes a lot of walking away.
Family and Relationships
Every 'take it or leave it' ever issued across a kitchen table, and the reliable discovery that people will leave it.