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Togetherness vs the Simple Theory of Joint Action

To gain a deeper understanding of the Simple Theory of Joint Action, consider an objection it faces: in invoking intentions to do things together, the Simple Theory is presupposing the very thing it was supposed to characterise.

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This is a highly optional section covering some advanced material. It fits here, but the reasons it matters will only become apparent later. Please skip it if you do not have time to study all the sections this week.

The Objection from Togetherness

  1. The Simple Theory of Joint Action depends on agents having intentions to do things together.

  2. For two or more people to do something together is for them to perform an intentional joint action.[1]

  3. Therefore, the Simple Theory presupposes the notion of intentional joint action, the very thing it was supposed to characterise.

Reply to the Objection

For each of the following sentences minus the ‘together’, there is a collective interpretation:

a. The tiny drops soaked Zach’s trousers [together].

b. The three legs of the tripod support the camera [together].

c. Ayesha and Beatrice lifted the block [together].

The collective interpretation makes adding ‘together’ appropriate.

It is the same sense of ‘together’ in each case, (a)-(c).

The truth of the collective interpretation of (c) does not depend on there being any intentional joint action. (As the contrivance introduced in the recording shows, Ayesha and Beatrice need have no awareness of each other’s existence or actions; nor need they have intentions concerning anyone else.)

Therefore, two or more people can do something together without thereby performing a joint action. This contradicts premise (2) of the objection.

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Simple Theory of Joint Action : Two or more agents perform an intentional joint action exactly when there is an act-type, φ, such that each agent intends that they, these agents, φ together and their intentions are appropriately related to their actions.


Dejean, A., Solano, P. J., Ayroles, J., Corbara, B., & Orivel, J. (2005). Insect behaviour: Arboreal ants build traps to capture prey. Nature, 434, 973.
Gilbert, M. P. (2010). Collective action. In T. O’Connor & C. Sandis (Eds.), A companion to the philosophy of action (pp. 67–73). Oxford: Blackwell.
Gilbert, M. P. (2013). Joint commitment: How we make the social world. Oxford: Oxford University Press. Retrieved from
Schweikard, D. P., & Schmid, H. B. (2013). Collective intentionality. In E. N. Zalta (Ed.), The stanford encyclopedia of philosophy (Summer 2013). Metaphysics Research Lab, Stanford University. Retrieved from


  1. Gilbert appears committed to this claim, for she writes that ‘[t]he key question in the philosophy of collective action is simply ... under what conditions are two or more people doing something together?’ (Gilbert, 2010, p. 67). She also suggests that ‘two or more people are acting together if [and only if] they are jointly committed to espousing as a body a certain goal, and each one is acting in a way appropriate to the achievement of that goal, where each one is doing this in light of the fact that he or she is subject to a joint commitment to espouse the goal in question as a body’ (Gilbert, 2013, p. 34). It is possible that she is using ‘together’ in a special technical sense (although she does not say that she is). ↩︎