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What Is Team Reasoning?

‘You and another person have to choose whether to click on A or B. If you both click on A you will both receive £100, if you both click on B you will both receive £1, and if you click on different letters you will receive nothing. What should you do?’ (Bacharach 2006, p. 35) Game theory alone cannot explain why your both choosing A is more rational than your both choosing B. Team Reasoning is an attempt to improve on game-theory and offers an explanation of this. But what is team reasoning?

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This section depends on you having studied some other sections:


This section provides an informal explanation of team reasoning starting from Bacharach’s initial characterisation:

‘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)

What Is a Team?

Several different proposals have been made. Sugden (2000) proposes:

‘[A] team exists to the extent that its members take themselves to be members of it.’


‘[T]o take oneself to be a member of a team is to engage in such reasoning oneself, while holding certain beliefs about the use of such reasoning by others’

What Makes an Action Best Possible?

Sugden (2000) explains the contrast between the standard, game-theoretic way of thinking about best possible actions ...

‘In the standard theory, the individual appraises alternative actions by her in relation to some objective (her preferences), given her beliefs about the actions that other individuals will choose.’

... and the distinctive way of thinking about best possible actions that is characteristic of team reasoning:

‘An individual who engages in team-directed reasoning appraises alternative arrays of actions by members of the team in relation to some objective (team-directed preferences).’

‘At the level of the team, team preference is a ranking of outcomes which is revealed in the team's decisions.’

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 Dilemma[1] and Hi-Lo[1:1] (Bacharach, 2006; Sugden, 2000)

Alternative Approach

Although not covered in these lectures, Misyak & Chater (2014)’s proposal about virtual bargaining also looks like a promising development of game theory.

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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
Misyak, J. B., & Chater, N. (2014). Virtual bargaining: A theory of social decision-making. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1655), 20130487.
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.
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 Appendix: Index of Games ↩︎ ↩︎