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What Is Joint Action? Bratman’s Account

Minimally, an account of joint action should explain what distingiushes joint action from parallel but merely individual action.

What distingiushes joint action from parallel but merely individual action?

shared intention

Lots of philosophers and some psychologists think that all joint actions involve shared intention, and even that characterising joint action is fundamentally a matter of characterising shared intention.

‘I take a collective action to involve a collective [shared] intention.’


(Gilbert 2006, p. 5)

‘The sine qua non of collaborative action is a joint goal [shared intention] and a joint commitment’


(Tomasello 2008, p. 181)

‘the key property of joint action lies in its internal component [...] in the participants’ having a “collective” or “shared” intention.’


(Alonso 2009, pp. 444-5)

‘Shared intentionality is the foundation upon which joint action is built.’


(Carpenter 2009, p. 381)


shared intention

It is helpful to draw a parallel with individual action ... Consider Davidson’s question is, Which events are actions?
Suppose we ask, Which events are actions? (This is Davidson’s question.) Here the contrast is with things that merely happen to an agent. To illustrate, we might be struck by the contrast between your arm being caused to go up by forces beyond your control, and the action you perform when you raise your arm. Or we might be struck by the contrast between mere reflexes, such as the eyeblink reflex, and the action of blinking your eyes (perhaps to greet someone).
One quite natural and certainly influential way to answer this question is by appeal to intention. The idea is that events are actions in virtue of being appropriately related to an intention of yours.
Note that I’m not confidently endorsing this answer; in fact I’m not even confident that the question is ultimately the right question to ask. I’m just suggesting this is a reasonably straightforward starting point for us.
This question about ordinary, individual action is parallel to our current working question about joint action, which we might phrase as ‘Which events are *joint* actions’ ...
Now we can see one attraction of appealing to shared intention. It allows us to give a parallel answer to the question about joint action: a joint action is an event which is appropriately related to a shared intention.
So to the extent that we are persuaded by the standard account of which events are actions, it is natural to aim for a structurally parallel account of which events are joint actions. To do this we merely have to characterise shared intentions.
As we shall see, there are long running, deep conflicts over the nature of shared intention. The range of different approaches can be quite daunting. This parallel between intention and shared intention is important because it is a rare point on wihch almost everyone will agree. \textbf{Despite the disagreement on details, I think one thing almost everyone agrees about is this: shared intention is to joint action at least approximately what ordinary individual intention is to ordinary, individual action.}
It’s important to acknowledge that we haven’t yet said anything very informative about what shared intention is. The question was, Which events are joint actions? The answer was, those which stand in an appropriate relation to a shared intention. Then we ask what a shared intention is. And the answer is, it’s something in virtue of which events are joint actions. I don’t think the circle makes this completely useless; but I’m mentioning the circularity to stress that we don’t yet have an account of what shared intention is. An account of shared intention should to provide deep insight into the nature of shared agency.
‘I will … adopt Bratman’s … influential formulation of joint action … each partner needs to intend to perform the joint action together ‘‘in accordance with and because of meshing subplans’’ (p. 338) and this needs to be common knowledge between the participants.’
\citep[][p.\ 281]{carpenter:2009_howjoint}

Carpenter(2009, p. 281)

What is shared intention?

Functional characterisation:

shared intention serves to (a) coordinate activities, (b) coordinate planning and (c) structure bargaining


Inferential integration... and normative integration (e.g. agglomeration)

In making this idea more precise, Bratman proposes sufficient conditions for us to have a shared intention that we J ...

Substantial account:

We have a shared intention that we J if

‘1. (a) I intend that we J and (b) you intend that we J

‘2. I intend that we J in accordance with and because of la, lb, and meshing subplans of la and lb; you intend [likewise] …

‘3. 1 and 2 are common knowledge between us’

(Bratman 1993: View 4)

... the idea is then that an intentional joint action is an action that is appropriately related to a shared intention.
Explain the emergence of sophisticated human activities including referential communication and mindreading.
Joint action plays a role in explaining how sophisticated human activities emerge.

Can you anticipate a problem?