According to some views of reality, some objects are fundamental and other objects depend for their existence upon these fundamental objects. In this article, I argue that we have reason to reject these views.

I argue that an ecologically distributed conception of instrumental rationality can and should be extended to a socially distributed conception of instrumental rationality in social environments. The argument proceeds by showing that the assumption of exogenously fixed units of activity cannot be justified; different units of activity are possible and some are better means to independently given ends than others, in various circumstances. An important social heuristic, the mirror heuristic, enables the flexible formation of units of activity in game theoretic (...) situations, including collective units where these are instrumentally effective. In effect, the mirror heuristic makes the formation of units of activity endogenous to instrumental rationality. Moreover, the mirror heuristic is a conditional metaheuristic, which depends on mind reading of the heuristics of other players rather than on predictions of their behavior. Such mind reading can be regarded as emerging from an arms race between behavioral mimicry and ever smarter behavior reading. Even though unilateral mind reading may have benefits, the mirror metaheuristic illustrates that mutual mind reading has distinctive functions in responding to the challenges of social complexity. If simple heuristics can make us smart in the right environments, then social heuristics can make us smarter still. (shrink)

Payoff dominance, a criterion for choosing between equilibrium points in games, is intuitively compelling, especially in matching games and other games of common interests, but it has not been justified from standard game-theoretic rationality assumptions. A psychological explanation of it is offered in terms of a form of reasoning that we call the Stackelberg heuristic in which players assume that their strategic thinking will be anticipated by their co-player(s). Two-person games are called Stackelberg-soluble if the players' strategies that maximize against (...) their co-players' best replies intersect in a Nash equilibrium. Proofs are given that every game of common interests is Stackelberg-soluble, that a Stackelberg solution is always a payoff-dominant outcome, and that in every game with multiple Nash equilibria a Stackelberg solution is a payoff-dominant equilibrium point. It is argued that the Stackelberg heuristic may be justified by evidentialist reasoning. (shrink)

According to David Lewis, the prisoner's dilemma (PD) and Newcomb's problem (NP) are really just one dilemma in two different forms (Lewis 1979). Lewis's argument for this conclusion is ingenious and has been widely accepted. However, it is flawed. As this paper shows, the considerations that Lewis brings to bear to show that the game he starts with is an NP equally show that the game is not a PD.