Stag Hunts: fascinating and useful game theory model for collective action problems


4 Responses to “Stag Hunts: fascinating and useful game theory model for collective action problems”

  1. John says:

    Obligatory alumnus correction: JohnS Hopkins.

  2. bryanb says:

    So, in a stag hunt, all can win, get their best outcome, if they can coordinate. Typically that depends on trust, but having everyone on guard outside the classroom is a practical way to ensure that everyone is following the cooperative strategy.

    In a stag hunt there is a stable win-win Nash Equilibrium where no one has an incentive to defect. That contrasts with Prisoner’s Dilemma, where cooperation gets only second-best, and is unstable, since the individual incentive is to defect to get the best outcome (but if both defect, then both end up at second-worst.

    For an interesting synthesis of research on stag hunts and their implications, see Brian Skyrms, The Stag Hunt and the Evolution of Social Structure. 

    There is actually a family (or herd) of stag hunts, also known as coordination or assurance games, all with two Nash Equilibria, one of which is win-win where both get their best outcome, but variations in how the other payoffs are distributed. Robinson and Goforth’s topology of 2×2 games provides a way to map how these are related by swaps in payoffs. For some enhanced visualizations of the topology (that I’ve developed), see

  3. Philbert says:

    Can someone explain the relevance to Internet peering?

  4. Paul Harrison says:

    Yes! I’ve also heard this called a “coordination game”, and it requires a strangely recursive form of knowlege called “common knowledge”, knowledge that you know everyone knows, know everyone knows everyone knows, etc. Many of the stranger things people do in groups make sense when viewed as establishing common knowledge in order to win coordination games.

    See the book “Rational Ritual: Culture, Coordination, and Common Knowledge” by Michael Suk-Young Chwe.

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