Recall our question, What distinguishes joint actions from parallel but merely individual actions?
‘A first step is to say that what distinguishes you and me from you and the Stranger is that you and
I share an intention to walk together—we (you and I) intend to walk together—but you and the Stranger
do not. In modest sociality, joint activity is explained by such a shared intention; whereas no such
explanation is available for the combined activity of you and the Stranger. This does not, however,
get us very far; for we do not yet know what a shared intention is, and how it connects up with joint
action’ \citep[p.~152]{Bratman:2009lv}.
‘A first step is to say that what distinguishes’ the sisters cycling together from the strangers cycling side by side is that the sisters to cycle together ... but the strangers do not.
Bratman, 2009 p. 152
Parallel with individual action ...
It is helpful to draw a parallel with individual action ...
Consider Davidson’s question
‘What events in the life of a person reveal agency; what are his deeds and his doings in contrast to mere happenings in history; what is the mark that distinguishes his actions?’
Davidson (1971, p. 43)
\citep[p.~43]{Davidson:1971fz}
It is perhaps helpful to think of this question by contrasing actions 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).
‘Echoing Wittgenstein's question about the difference, in the individual case,
between my arm's rising and my raising it, we can ask: what is the difference
between such a contrast case and corresponding shared intentional activity?
In the case of individual intentional human action, we can see the difference from
a contrast case as involving an explanatory role of relevant intentions of the
individual agent. ... I propose an analogous view ofthe shared case: the difference
in the case of shared agency involves an appropriate explanatory role of relevant
shared intentions. Our painting together is a shared intentional activity,
roughly, when we paint together because we share an intention so to act.’
\citep[p.~10]{bratman:2014_book}
In short, 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.