Conflict between safety and cooperation
This article is about the game theory problem about stag hunting. For the painting about stag hunting, see
Stag Hunt. For stag hunting, see
Deer hunting.
In game theory, the stag hunt, sometimes referred to as the assurance game, trust dilemma or common interest game, describes a conflict between safety and social cooperation. The stag hunt problem originated with philosopher Jean-Jacques Rousseau in his Discourse on Inequality. In the most common account of this dilemma, which is quite different from Rousseau's, two hunters must decide separately, and without the other knowing, whether to hunt a stag or a hare. However, both hunters know the only way to successfully hunt a stag is with the other's help. One hunter can catch a hare alone with less effort and less time, but it is worth far less than a stag and has much less meat. But both hunters would be better off if both choose the more ambitious and more rewarding goal of getting the stag, giving up some autonomy in exchange for the other hunter's cooperation and added might. This situation is often seen as a useful analogy for many kinds of social cooperation, such as international agreements on climate change.[1]
The stag hunt differs from the prisoner's dilemma in that there are two pure-strategy Nash equilibria:[2] one where both players cooperate, and one where both players defect. In the Prisoner's Dilemma, in contrast, despite the fact that both players cooperating is Pareto efficient, the only pure Nash equilibrium is when both players choose to defect.
An example of the payoff matrix for the stag hunt is pictured in Figure 2.
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Stag
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Hare
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| Stag
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a, a
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c, b
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| Hare
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b, c
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d, d
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| Fig. 1: Generic symmetric stag hunt
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Stag
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Hare
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| Stag
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10, 10
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1, 8
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| Hare
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8, 1
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5, 5
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| Fig. 2: Stag hunt example
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