Domain 15
Faith and Community
Assurance and repetition do the work; costly participation acts as a signal of commitment.
Two mechanisms do most of it. Repetition with visibility means reputation enforces cooperation without any formal authority — small groups sustain contributions that large anonymous ones cannot. And costly participation works as a screen: requirements that seem inefficient from outside are effective at excluding people who would take without contributing, which is a well-supported explanation for why demanding groups are frequently more durable than undemanding ones.
The people who would join and cannot meet the entry cost, who are invisible precisely because the screen worked. Also those who left, whose reasons are rarely recorded anywhere.
What to look for
- Would people act if they believed others would? Then it is assurance, not apathy.
- Is the demanding requirement excluding free riders, or excluding people you wanted?
- Is contribution visible? Invisible contribution decays.
- Who is not here, and is their absence a design outcome?
The shapes that run this field
The Stag Hunt
Mutual cooperation is the best outcome for everyone, but it is risky — and the safe option is available unilaterally.
Shape 05Public Goods and the Free Rider
A non-excludable, non-rival good: contribution is privately costly and the return is shared, so it is underprovided.
Shape 07The Repeated Game
Repetition creates a future cost to defecting today, which can make cooperation individually rational without changing anyone's character.
Shape 12Costly Signalling
A costly, observable action that reveals private information because faking it would not pay.
Shape 04Pure Coordination
Multiple equilibria, no conflict of interest — the whole problem is agreeing which one.
In practice
Public Goods and the Free Rider
A rota that works when everyone can see the list and collapses when they cannot.
Costly Signalling
A group whose demanding commitments are what keep it durable rather than what limit it.
The Stag Hunt
A project everyone would join if they knew others were joining, and nobody starts.