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Why Investigate Team Reasoning?

There are at least three motives for us to investigate team reasoning. It provides a development of game theory which arguably better captures the notion of rational choice in many ordinary social interactions. It promises to provide an explanation of how there could be aggregate subjects. And it might provide an account of shared intention.

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This section introduces some motives for investigating team reasoning. Another section, What Is Team Reasoning?, explains what team reasoning is and the justification for supposing that it exists.


This section depends on you having studied some other sections:

Applications of Team Reasoning

Team reasoning can be drawn on in attempting, perhaps not always successfully, to provide:

  • an account of rational decision which differs from plain vanilla game theory on what is rational in many ordinary social interactions which have the structure of games like the Prisoner’s Dilemma1 and Hi-Lo1 (Bacharach, 2006; Sugden, 2000)

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aggregate subject : A subject whose proper parts are themselves subjects. A paradigm example would be a Portuguese man o' war (Physalia physalis), which is an animal that can swim and eat and whose swimming and eating is not simply a matter of the swimming or eating of its constituent animals. Distinct from, but sometimes confused with, a plural subject.
game theory : This term is used for any version of the theory based on the ideas of Neumann et al. (1953) and presented in any of the standard textbooks including. Hargreaves-Heap & Varoufakis (2004); Osborne & Rubinstein (1994); Tadelis (2013); Rasmusen (2007).
shared intention : An attitude that stands to joint action as ordinary, individual intention stands to ordinary, individual action. It is hard to find consensus on what shared intention is, but most agree that it is neither shared nor intention. (Variously called ‘collective’, ‘we-’ and ‘joint’ intention.)
team reasoning : ‘somebody team reasons if she works out the best possible feasible combination of actions for all the members of her team, then does her part in it’ (Bacharach, 2006, p. 121).


Bacharach, M. (2006). Beyond individual choice. Princeton: Princeton University Press. Retrieved from
Gold, N., & Sugden, R. (2007). Collective intentions and team agency. Journal of Philosophy, 104(3), 109–137.
Hargreaves-Heap, S., & Varoufakis, Y. (2004). Game theory: A critical introduction. London: Routledge. Retrieved from
Neumann, J. von, Morgenstern, O., Rubinstein, A., & Kuhn, H. W. (1953). Theory of Games and Economic Behavior. Princeton, N.J. ; Woodstock: Princeton University Press.
Osborne, M. J., & Rubinstein, A. (1994). A course in game theory. MIT press.
Pacherie, E. (2013). Intentional joint agency: Shared intention lite. Synthese, 190(10), 1817–1839.
Pettit, P. (2014). Group Agents are Not Expressive, Pragmatic or Theoretical Fictions. Erkenntnis, 79(9), 1641–1662.
Rasmusen, E. (2007). Games and information: An introduction to game theory (4th ed). Malden, MA ; Oxford: Blackwell Pub.
Sugden, R. (2000). Team preferences. Economics and Philosophy, 16, 175–204.
Tadelis, S. (2013). Game theory: An introduction. Princeton: Princeton University Press.
  1. These games are specified in the Index of Games  2