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Aggregate Subjects

Assume we do need a theory of shared intention in order to solve The Problem of Joint Action. Perhaps we construct such a theory using the idea that a shared intention is an intention of an aggregate subjects. Before doing this, we need to know what aggregate subjects are, whether there are any, and whether they could have intentions.

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Aggregate Subjects

Are there aggregate subjects and, if so, can they have intentions?

Theories of team reasoning require that teams can have preferences. To have a preference is to be a subject (of the preference), so teams are aggregate subjects.

If aggregate subjects can have not just preferences but also intentions, then it is possible that to have a shared intention is to be a part of an aggregate subject which has an intention.

Reductive Strategy

On the Reductive Strategy, there is no need for aggregate agents in constructing an account of shared intention.

On a view like Bratman (2014)’s, for us to have a shared intention is just for us each to have certain intentions and for this to be common knowledge among us.

This is a reductive strategy: nothing other than ordinary individual subjects need have intentions.

Background: Terminology

Why aggregate? From biology (an aggregate or colonial organism): Wikipedia: ‘the Portuguese man o' war is a colony of four different types of polyp or related forms’

Theories of group agency are theories of aggregate subjects.

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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.
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.)
The Problem of Joint Action : What distinguishes doing something jointly with another person from acting in parallel with them but merely side by side?


Bacharach, M. (2006). Beyond individual choice. Princeton: Princeton University Press. Retrieved from
Bratman, M. E. (2014). Shared agency: A planning theory of acting together. Oxford: Oxford University Press. Retrieved from
Dixit, A., Skeath, S., & Reiley, D. (2014). Games of strategy. New York: W. W. Norton; Company.
Gold, N., & Sugden, R. (2007). Collective intentions and team agency. Journal of Philosophy, 104(3), 109–137.
Helm, B. W. (2008). Plural agents. Nous, 42(1), 17–49.
Sugden, R. (2000). Team preferences. Economics and Philosophy, 16, 175–204.