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\title {Joint Action \\ Lecture 05}

\maketitle

Lecture 05

Joint Action

[email protected]

\def \ititle {Lecture 05}

\def \isubtitle {Joint Action}

\begin{center}

{\Large

\textbf{\ititle}: \isubtitle

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\iemail %

\end{center}

\section{Shared Intention and Development}

Several philosophers have suggested that Bratman’s account of shared intention cannot be the full story if an interesting conjecture about the role of joint action in development is true. What is the objection from development? How might a defender of Bratman’s approach counter it?

challenge

Explain the emergence of sophisticated human activities including referential communication and mindreading.

The challenge is to explain the emergence, in evolution or development, of sophisticated forms of human activity including, referential communication and mindreading.

A number of researchers have suggested that meeting this challenge requires us to invoke some kind of social interaction ...

According to what Moll and Tomasello call the Vygotskian Intelligence Hypothesis,

‘participation in cooperative ... interactions … leads children to construct uniquely powerful forms of cognitive representation.’

(Moll & Tomasello 2007)

\citep{Moll:2007gu}

‘perception, action, and cognition are grounded in social interaction’

(Knoblich & Sebanz 2006)

\citep[p.\ 103]{Knoblich:2006bn}

‘human cognitive abilities … [are] built upon social interaction’

(Sinigaglia and Sparaci 2008)

\citep{sinigaglia:2008_roots}

I'm going to assume that they are right.

If we take these ideas seriously, the first question we need to ask is, What kinds of social interaction matters for the emergence of sophisticated human activities?

What kinds of social interaction? Joint actions!

There seems to be some consensus on the idea that joint action is particularly important.

But what is joint action?

challenge

Explain the emergence of sophisticated human activities including referential communication and mindreading.

So the challenge was to explain the emergence of sophisticated human activities including referential communication and mindreading.

conjecture

Joint action plays a role in explaining how sophisticated human activities emerge.

The conjecture I want to consider, borrowed from a variety of researchers, is that joint action plays a role in explaining how sophisticated human activities emerge. There is a compelling objection to this conjecture. It will take me a while to explain what the objection is. The objection arises when we ask ask what joint action is.

(a) All joint action involves shared intention.

(b) Bratman is right about shared intention.

‘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)

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

... the idea is then that an intentional joint action is an action that is appropriately related to a shared intention.

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)

Note that the conditions require not just that we intend the joint action, but that we intend it because of each other's intentions, where this is common knowledge.

So we need not just intentions about intentions ...

... also you need to know things about my knowledge of your intentions concerning my intentions.

This indicates that, in general, having shared intentions requires mindreading at close to (or perhaps just beyond) the limits of most adult humans' abilities. Bratman's account of shared intention is an example where reciprocity is modeled as higher-order escalation.

Objection: Meeting the sufficient conditions for joint action given by Bratman’s account could not significantly \textit{explain} the development of an understanding of minds because it already \textit{presupposes} too much sophistication in the use of psychological concepts.

And this is a problem for us ...

challenge

Explain the emergence of sophisticated human activities including referential communication and mindreading.

conjecture

Joint action plays a role in explaining how sophisticated human activities emerge.

This is a problem because our conjecture was that joint action plays a role in explaining how sophisticated human activities emerge.

objection

Joint action presupposes mindreading at the limits of human abilities.

But if joint action presupposes mindreading at close to the limits of human abilities, and if mindreading abilities are a paradigm case of humans' cognitive sophistication, then we must reject the conjecture. For in appealing to joint action we would be presupposing what was supposed to be explained. In what follows I want to defend the conjecture by identifying a way around the objection.

But before I do this, I want to mention a problem with the objection ...

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)

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.)

As it stands, then, this objection does not establish much. It concerns conditions imposed by the substantial account of shared intention which are sufficient but not necessary conditions. The substantial account is supposed to characterise one—perhaps one among many—ways in which the functional role of shared intentions can be realised. So the objection serves only to raise a question.

\textbf{Are there in fact alternative sufficient conditions for shared intention, conditions that can be met without already having abilities to use psychological concepts whose development was supposed to be explained by joint action?}

The answer to this question is not entirely straightforward. We must begin with the functional roles of shared intention, for these provide necessary conditions. One of the roles of shared intentions is to coordinate planning. What does coordinating planning involve? Intuitively the idea is that just as individual intentions serve to coordinate an individual’s planning over time, so shared intentions coordinate planning between agents. (I use the terms ‘individual intention’ and ‘individual goal’ to refer to intentions and goals explanatory of individual actions; an ‘individual action’ is an action performed by just one agent such as that described by the sentence ‘Ayesha repaired the puncture all by herself’.) A second role for shared intentions is to structure bargaining concerning plans. To understand these roles it is essential to understand what ‘planning’ means in this context. The term ‘planning’ is sometimes used quite broadly to encompass processes involved in low-level control over the execution of sequences of movements, as is often required for manipulating objects manually \citep[e.g.][]{en_1535}, as well as processes controlling the movements of a limb on a single trajectory \citep[e.g.][]{en_1681}. In Bratman’s account and this paper, the term ‘planning’ is used in a narrower sense. Planning in this narrow sense exists to coordinate an agent’s various activities over relatively long intervals of time; it involves practical reasoning and forming intentions which may themselves require further planning, generating a hierachy of plans and subplans. Paradigm cases include planning a birthday party or planning to move house.

Given the functional roles of shared intention, when (if ever) must the states which realise shared intentions include intentions about others’ intentions? Coordinating plans with others does not seem always or in principle to require specific intentions about others’ intentions. It is plausible that in everyday life some of our plans are coordinated largely thanks to a background of shared preferences, habits and conventions. Consider, for example, people who often meet in a set place at a fixed time of day to discuss research over lunch. These people can coordinate their lunch plans merely by setting a date and following established routine; providing nothing unexpected happens, they seem not to need intentions about each other’s intentions. Within limits, then, coordinating plans may not always require intentions about intentions. The same may hold for structuring bargaining. But when the background of shared preferences, habits and conventions is not sufficient to ensure that our plans will be coordinated, it is necessary to monitor or manipulate others’ plans. And since intentions are the basic elements of plans (in the special sense of ‘plan’ in terms of which Bratman defined shared intention), this means monitoring or manipulating others’ intentions. The background which makes for effortlessly coordinated planning is absent when our aims are sufficiently novel, when the circumstances sufficiently unusual (as in many emergencies), and when our co-actors are sufficiently unfamiliar. In all of these cases, coordinating plans and structuring bargaining will involve monitoring or manipulating others’ intentions. Now this does not necessarily involve forming intentions about their intentions because, in principle, monitoring and manipulating others’ intentions could (within limits) be achieved by representing states which serve as proxies for intentions rather than by representing intentions as such, much as one can (within limits) monitor and manipulate others’ visual perceptions by representing their lines of sight. But possession of general abilities to monitor and manipulate others’ intentions does require being able to form intentions about others’ intentions.

The question was whether there are sufficient conditions for shared intention which do not presuppose abilities to use psychological concepts whose development is supposed to be explained by joint action. As promised, the answer is not straightforward. In a limited range of cases, coordinating plans and perhaps structuring bargaining does not appear to require insights into other minds. But in other cases, particularly cases involving novel aims or agents unfamiliar with each other, intentions about others’ intentions are generally required.

The main question for this section was whether Bratman’s account captures a notion of joint action suitable for explaining the early development of children’s abilities to think about minds. Some of the joint actions which young children engage in involve novel aims, and some involve unfamiliar partners. So if these joint actions did involve coordinating planning and structuring bargaining, they could not rest on a shared background but would require abilities to form intentions about others’ intentions. It follows that joint action would presuppose much of the sophistication in the use of psychological concepts whose development it was supposed to explain. So given the premise that joint action plays a role in explaining early developments in understanding minds, it cannot be the case that the joint actions children engage in as soon as they engage in any joint actions involve shared intentions as characterised by Bratman.

challenge

Explain the emergence of sophisticated human activities including referential communication and mindreading.

conjecture

Joint action plays a role in explaining how sophisticated human activities emerge.

objection

Joint action presupposes mindreading at the limits of human abilities.

How to get around the objection?

1. joint action fosters an understanding of minds;

2. all joint action involves shared intention; and

3. a function of shared intention is to coordinate two or more agents’ plans.

The objection arises because not all of the following claims are true: % \begin{quote} (1) joint action fosters an understanding of minds; (2) all joint action involves shared intention; and (3) a function of shared intention is to coordinate two or more agents’ plans. \end{quote} % These claims are inconsistent because if the second and third were both true, abilities to engage in joint action would presuppose, and so could not significantly foster, an understanding of minds.

What are our options?

This is a bad option; it either involves rejecting claims about intention that amount to saying there is no such thing as intention, or else it involves breaking the parallel between intention and shared intention. But that parallel is pretty much all we have to anchor or understanding of shared intention.

Bratman already refuted? No. But we need more.

At this point we might take Bratman as a rock around which to build. I thought for a long time that this was the right approach. But more recently I discovered an apparently compelling objection to Bratman’s whole approach ...

A Counterexample to Bratman

\section{A Counterexample to Bratman}

No one has yet offered a convincing counterexample to Bratman’s account of shared agency in print. I think there is one, though. If successful, the counterexample motivates considering alternative, more exotic approaches.

I want to start by considering an objection to Bratman which I think is misguided, because seeing how this objection is misguided is the key to understanding what is wrong with Bratman’s account.

Having a shared intention involves us each intending that we, you and I, φ together.

Bratman

‘Bratman’s account presupposes the element of sharedness it aims to explain.’

\citep[p.~36]{schmid:2009_plural_bk}

‘It is only because we intend to J that I can have intentions of the form “I intend that we J”’

\citep[p.~36]{schmid:2009_plural_bk}

‘Bratman’s ... account of shared intentionality ... fails to give an account of the crucial element of collectiveness that is presupposed at its very base’

\citep[p.~37]{schmid:2009_plural_bk}

[The reply to Schmid is the people who block the asile, or the Tarantino walkers.]

Full quote: ‘Consider the following example. If we jointly intend to meet for lunch today, it does not seem necessary – indeed it is redundant – for me to form an intention of the form “I intend that we meet for lunch today” (rather, I will typically form some we-derivative [Sellars 1980: 99] or participatory [Kutz 2000a] intention of the kind “I intend to call you before noon to arrange a meeting place”). If and only if I take myself to be in a position to have a say in that matter, I might form an additional intention that specifies the content of our we-intention, and this additional intention might be of the form “I intend that we Jx” (e.g., “I intend that we have lunch together at the Japanese restaurant”). But intentions of this sort presuppose shared intentions instead of being their building blocks. It is only because we intend to J that I can have intentions of the form “I intend that we J”. Thus it seems that Bratman’s “reductive” account of shared intentionality “in terms of attitudes and actions of the individuals involved” (1999: 108) simply fails to give an account of the crucial element of collectiveness that is presupposed at its very base, because he endorses formal individualism.’

Schmid (2009, p. 36)

I think Schmid is wrong that Bratman’s presupposes collectiveness. Quite the opposite: I think it fails to capture collectiveness. So my objection takes a line opposite Schmid’s (and cannot be correct unless his objection is wrong).

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)

Blomberg (personal communication)

Ayesha and Beatrice are bitter rivals. They each have one wrist handcuffed to the steering wheel of the same moving car. They are matched in strength closely enough that neither can decide the car’s course alone: its movements will be a consequence of both of their actions.

Ayesha, determined that Beatrice should die and wishing to die herself, is wondering how she could bring this about. Thinking that she could pull her gun on Beatrice to force her to cooperate, she intends, unilaterally, that they, Ayesha and Beatrice, drive the car off the road and over a cliff.

If they now drive off the cliff in accordance with Ayesha’s intention, they won’t be exercising shared agency. Contrast this case with Thelma and Louise’s better known and more romantic intentional car crash (the two friends evade capture by driving off a cliff together; Khouri 1992). Whereas Thelma and Louise’s escape is a paradigm case of collective agency, the initial episode involving Ayesha and Beatrice does not seem to involve collective agency at all.

But now change how it happens. Let a sudden jolt causes the gun to fly from her hand and land far out of reach. Just as it seems she will have to abandon her intention, it strikes her that Beatrice has an intention which renders the gun unnecessary. For Beatrice, whose thoughts and actions mirror Ayesha’s, plainly intends what Ayesha intends, namely that they drive the car over the cliff. So Ayesha retains this intention and changes her mind only about the means.

Is this change enough to transform Ayesha and Beatrice’s actions into a joint action? If it is, Bratman’s account is in trouble---it would be a counterexample.

I used to think this is a counterexample, but now I’m not so sure. What do you think.

Is it a counterexample?

[btw] A counterexample to the sufficiency of Bratman’s conditions for shared intention is also a counterexample to the Simple View.

a second attempt

\begin{minipage}{\columnwidth}

We have an \emph{unshared intention} that we <J$_1$, J$_2$> where J$_1$$\neq$J$_2$ just if:

\begin{enumerate}[label=({\arabic*$^\prime$}),itemsep=0pt,topsep=0pt]

\item (a) I intend that we J$_1$ and (b) you intend that we J$_2$

\item I intend that we J$_1$ in accordance with and because of la, lb, and meshing subplans of la and lb; you intend that we J$_2$ ...

\item 1 and 2 are common knowledge between us.

\end{enumerate}

\end{minipage}

Our individual subplans concerning our <J$_1$, J$_2$>-ing \emph{mesh} just in case there is some way I could J$_1$ and you could J$_2$ that would not violate either of our subplans but would, rather, involve the successful execution of those subplans.

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 conditions for unshared intention are just like those for shared intention except that they concern two distinct activities, J1 and J2.

So for you and I to have an unshared intention that we , ...

If it is possible for Bratman's sufficient conditions for shared intention to be met without relevant irrationality or ignorance, then it is likewise possible for these conditions on unshared intention to be met.

Here is an example of two people who have an unshared intention.

Ayesha and Ahmed. They can each tilt the table, but only along one axis.

(Note that Ayesha can unilaterally intend that they, Ayesha and Ahmed, make the ball hit the red square.)

Ayesha and Ahmed meet the conditions for unshared intention concerning hitting the blue cross and hitting the red square. And their actions are appropriately related to their intentions.

Ayesha and Ahmed are not acting as one (or exercising shared agency). This is not just a matter of their having different intentions, I think. More fundamentally, each sees the other’s intentions merely as constraints to work around or opportunities to exploit. While I don’t think that viewing another’s intentions in this way is entirely incompatible with acting as one, in Ayesha and Ahmed’s case each views the other’s intentions *merely* as opportunities to exploit or constraints to work around. And this is, surely, incompatible with acting as one. (*Qualified in the book chapter for Catrin Misselhorn.)

If you think Ayesha and Ahmed are having a bad hair day, you should see Beatrice and Baldric ...

Now explain that Ayesha and Ahmed have an unshared intention, but Beatrice and Baldric have a shared intention.

I claim that Beatrice and Baldric have a shared intention that they J$_1$ only if Ayesha and Ahmed have a shared intention. This claim follows from the similarities of the two cases. The only difference is that Beatrice and Baldric happen to have same task, whereas Ayesha and Ahmed have different tasks. But neither Beatrice nor Baldric makes use of the fact that they have the same task. So if we consider how Beatrice and Baldric's case differs from Ayesha and Ahmed’s, we can see that these differences do not plausibly amount to a difference with respect to shared agency. Shared intention cannot feature in one case but not the other.

This is a bit delicate. I am supposing that Beatrice and Baldric are each making use of the fact that Beatrice intends J1 and of the fact that Baldric intends that J2, but that they are neglecting to make any use of the fact that J1=J2.

So the only difference is that Beatrice and Baldric happen to have same task, whereas Ayesha and Ahmed have different tasks. But neither Beatrice nor Baldric makes use of the fact that they have the same task.

Beatrice does rely on the fact Baldric intends that they J1, of course; but she does not rely on the fact that what Baldric intends is what she intends.

true? A&A make use of?
Ayesha intends J₁ ✓ ✓
Ahmed intends J₂ ✓ ✓
J₁=J₂ ✗ ✗

	true?	A&A make use of?
Ayesha intends J₁	✓	✓
Ahmed intends J₂	✓	✓
J₁=J₂	✗	✗

true? B&B make use of?
Beatrice intends J₁ ✓ ✓
Baldric intends J₂ ✓ ✓
J₁=J₂ ✓ ✗

	true?	B&B make use of?
Beatrice intends J₁	✓	✓
Baldric intends J₂	✓	✓
J₁=J₂	✓	✗

So I take this case to be an objection to the idea that we can explain acting as one by appeal to shared intention if we also accept Bratman's claims about what is sufficient for shared intention.

So, at least provisionally, we can add Beatrice & Baldric to the right side of our list of cases of parallel but merely individual action.

This is a case where we have interconnected planning but no shared agency.

I'll strengthen the case for denying that BnB have a shared intention later by constructing a contrasting case in which there really is a shared intention.

(I might mention that there are also mundane counterexamples.)

Joint Action

Parallel but Merely Individual Action

Two people making the cross hit the red square in the ordinary way.

Beatrice & Baldric’s making the cross hit the red square

Two sisters cycling together.

Two strangers cycling the same route side-by-side.

Members of a flash mob simultaneously open their newspapers noisily.

Onlookers simultaneously open their newspapers noisily.

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)

So I reject two attempts to say what is involved in acting as one. The Simple View fails because it is possible to meet this condition while walking in the Tarantino sense, and the Bratman-esque Shared Intention Account fails because it’s possible to meet these conditions in a situation where you are merely treating others’ intentions as opportunities to exploit and constraints to work around.

Acting as one requires more than this (and perhaps less than this too). But what is missing?

The problem I think is that we are failing to capture the agents’ perspective. Acting as one is in part a matter of how things seem to the agent. It is also, I think, partly a matter of the agents exploiting the fact that they each intend the same thing, or that their actions have a collective goal. But how can we get from such an intuition to a theoretical account of acting as one?

Bratman’s idea that we can get at shared agency by shifting from intentions to intentions about intentions faces a putative counterexample.

Bratman’s brilliant idea for avoiding this sort of problem is to suggest that we don’t just each intend the action but rather we each intend to act by way of the other's intentions.

We can put this by saying that our intentions must interlock: mine specify yours and yours mind.

Now this appeal to interlocking intentions enables Bratman to avoid counterexamples like the Tarantino walkers; if I intend that we walk by way of your intention that we walk, I suppose can't rationally also point a gun at you and coerce you to walk.

‘each agent does not just intend that the group perform the […] joint action.

‘Rather, each agent intends as well that the group perform this joint action in accordance with subplans (of the intentions in favor of the joint action) that mesh’

(Bratman 1992: 332)

conclusion

In conclusion, ...

Given a conjecture about development, Bratman’s account cannot be the whole story about joint action.
There is a (putative) counterexample to Bratman’s account

Bratman’s account is excellent and it is difficult (but perhaps not impossible) to provide convincing objections to it. It would be reasonable to continue investigating it rather than moving on. But for my part, I’m provisionally convinced by the counterexample.

so?

Either we need an alternative way of answering our question, What distinguishes merely parallel from genuinely joint action?

Or else maybe there is something wrong with the question itself.

Either way, there is probably plenty we can learn from Bratman’s account, even if it fails. (It certainly serves as the key reference point for almost all philosophers writing about joint action.)

For my part, I’m open to the idea that we are asking the wrong question. But I think it’s too early to conclude that. What we need instead is to search, in what philosophers other than Bratman have written, for alternative theories ...

Is Common Knowledge Necessary?

\section{Is Common Knowledge Necessary?}

Many accounts of joint action assume, mostly without argument, that common knowledge is necessary for intentional shared agency. But is it? Blomberg (2015) argues that it is not.

What is shared intention?

Substantial account:

Bratman isn’t saying that common knowledge is necessary, but other accounts do. And why should Bratman mention it at all?

‘Miller (2001, 60) submits that ‘mutual knowledge is what distinguishes joint action from interdependent action that is not joint’, but never explains why mutual knowledge has this transformative power’

Blomberg, 2015 p. 3

Last piece of business: why require common knowledge in the construction of shared intention?

Why common knowledge?

Facts about your intentions feature in my planning.

Only known facts can feature in my planning.

Therefore *knowledge* is required.

do we get from here to *common* knowledge?

‘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.’

Bratman (2015, p. 57)

\citep[p.~57]{bratman:2014_book}

What is Bratman saying? I’m not sure.

What I intend depends on my knowledge of what you intend

... which depends on your knowledge of what I intend

... which depends on my knowledge of what you intend

...

Keyboard Shortcuts?

Lecture 05

Joint Action

[email protected]

A Counterexample to Bratman

Is Common Knowledge Necessary?

Keyboard Shortcuts`?`