Bratman on Shared Intention

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Bratman on Shared Intention

So I wanted to start by showing you his picture.

Bratman (2009, p. 150) starts with our question, What distinguishes ...?

But he immediately goes on to say, ‘Step back: what do we want from an answer to this question?’

‘three main concerns: conceptual, metaphysical, and normative.

‘We seek an articulated conceptual framework that adequately supports our theorizing about modest sociality;

‘... to understand what in the world constitutes such modest sociality;

‘and ... an understanding of the kinds of normativity—the kinds of ‘oughts’—that are central to modest sociality.

‘And throughout we are interested in the relations—conceptual, metaphysical, normative—between individual agency and modest sociality.’

Why is this a reasonable strategy? One consideration is that, developmentally and evolutionarily, modest sociality almost certainly came first. So it is reasonable to hope that if we can understand this, we can build up to more complex cases. Another, related thought is Fred Dretske’s maxim that you don’t know how something works until you know how to build it. It is a reasonable guess that in building agents capable of exercising shared agency, a good first target is to get them started with modest sociality.

Note that this is only a starting point: we are also going to consider large scale joint actions (like electing a president) and very small scale joint actions (like sharing a smile or moving an egg).

the continuity thesis

‘once God created individual planning agents and ... they have relevant knowledge of each other’s minds, nothing fundamentally new--conceptually, metaphysically, or normatively--needs to be added for there to be modest sociality.’

Bratman (2015, p. 8)

\citep[p.~8]{bratman:2014_book}

What is shared intention?

Functional characterisation:

Substantial account:

To illustrate: if we share an intention that we cook dinner, this shared intention will (iii) structure bargaining insofar as we may need to decide what to cook or how to cook it on the assumption that we are cooking it together; the shared intention will also require us to (ii) coordinate our planning by each bringing complementary ingredients and tools, and to (i) coordinate our activities by preparing the ingredients in the right order.

The functional characterisation is really important: if we accept it, then it tells a lot about what shared intentions could and could not be. In particular, it either rules out Searle’s account or at least shows that the account is not clearly an account of shared intention because it does not explain how the attitude Searle characterises, the ‘we-intention’ could coordinate activities, coordinate planning and structure bargaining.

inferential integration ... [illustrate with planning example where you have to plan both individual and joint action]

normative integration (e.g. agglommeration)

[illustrate agglomeration for individual case first, then joint]

These points are extremely simple but also extremely powerful. They are powerful because they create problems for many approaches to shared agency. Consider Searle’s view again. He thinks that shared intentions are not intentions but a new, sui generis kind of attitude (which is why he uses the term ‘we-intentions’). If you think this, you have to explain how come the new attitudes are inferentially and normatively integrated with ordinary intentions. (I’m not saying this can’t be done, just that doing it is challenging, and certainly not something that Searle has attempted as far as I know.)

We’ll shortly see how the substantial account is built step by step. But maybe it’s helpful to mention the strategy

creature construction is an idea from Grice ...

the construction ...

step 1

‘Our shared intention to paint together involves your intention that we paint and my intention that we paint.’

Bratman (2015, p. 12)

\citep[p.~12]{bratman:2014_book}

(Compare the Simple View)

This is roughly what the simple view said This might seem completely innocuous, but it is interestingly controversial.

the ‘mafia case’* motivates ... and painting the house different colours motivates ...

step 2

We each intend that we paint by way of the intentions that we paint* and by meshing* subplans of these intentions.

Given what I said earlier, I don’t think the mafia case actually motivates step 2. But I did provide other cases (the Tarantino walkers and blocking the asile) which do seem to motivate step 2.

star: complication ‘and that the route from these intentions to our joint activity satisfies the connection condition’ \citep[p.~52]{bratman:2014_book}.

On the connection condition: It is ‘the condition that specifies the nature of [the] explanatory relation’ between shared intention and joint action \citep[p.~78]{bratman:2014_book}.. ‘the basic idea is that what is central to the connection condition is that each is responsive to the intentions and actions of the other in ways that track the intended end of the joint action--where all this is out in the open.’ \citep[p.~79]{bratman:2014_book}.

We intend to paint the house, but I blue and you red. Earlier work: I trick you ... In the book: ‘we have a problem. In a case of shared intention we will normally try to resolve that problem by making adjustments in one or both of these sub-plans, perhaps by way of bargaining, in the direction of co-possibility. So we want our construction to account for is standard social norm-responsive functioning of the shared intention.’ \citep[p.~53]{Bratman:2012fk}

meshing subplans are required

star: meshing

‘The sub-plans of the participants \emph{mesh} when it is possible that all of these sub-plans taken to gether be successfully executed.’ \citep[p.~53]{bratman:2014_book}

So much for step 2; now we come to the last major step (I’m skipping some details.)

why??

step 3

‘there is common knowledge among the participants of the conditions cited in this construction’

Bratman (2015, p. 58)

\citep[p.~58]{bratman:2014_book}

Why impose the common knowledge condition? Before discussing this [I might have to skip discussion of this, but there is a useful quote on the handout], let me provide a summary of where we are with Bratman’s account.

Why require common knowledge in the construction of shared intention? ‘in shared intention the fact of the shared intention will normally be out in the open: there will be public access to the fact of shared intention. Such public access to the shared intention will normally be involved in further thought that is characteristic of shared intention, as when we plan together how to carry out our shared intention. Since such shared planning about how to carry out our shared intention is part of the normal functioning of that shared intention, we need an element in our construction of shared intention whose functioning supports some such thinking of each about our shared intention.’ \citep[p.~57]{bratman:2014_book}

What is shared intention?

Functional characterisation:

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

Constraint:

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

Substantial account:

These are the conditions that we have been discussing.

Note that these conditions are offered as sufficient but not necessary. (Bratman originally claimed that they were necessary and sufficient, but nothing in the construction rules out alternative realisations of the functional characterisation of shared intention.)

Are sufficient conditions sufficient for achieving Bratman’s aims? Bratman’s pitch is this. Recall the continuity thesis (‘once God created individual planning agents and ... they have relevant knowledge of each other’s minds, nothing fundamentally new--conceptually, metaphysically, or normatively--needs to be added for there to be modest sociality.’ p.8) Bratman reasons that if we can give sufficient conditions for shared agency that are consistent with the continuity thesis, then our default assumption should be that shared agency does not require concepual, metaphysical or normative innovation.

So if we accept Bratman’s sufficient conditions, then we should also accept the continuity thesis. (There might issues about whether merely sufficient conditions are enough to fulfil his aim of providing a framework for theorising about shared agency; more on this when we come to consider joint action and development.)

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Bratman on Shared Intention

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