Luke Roelofs (Australian National University)
Intentional explanation is a strikingly useful form of explanation, and human life would be unrecognisable if we did not routinely apply it to the understanding of individual behaviour. So it is not surprising that we routinely also use the idiom of intentional explanation – of beliefs, desires, and actions aimed at satisfying those desires according to those beliefs – to talk about human collectives. After all, if we could explain collective behaviour by reference to collective beliefs and desires, that would be a major explanatory boon. On the other hand, if we applied this explanatory scheme to phenomena which do not fit it, we would simply be entangling ourselves in unproductive metaphors. The philosophical project of analysing collective intentionality is important because it helps us to see when intentional explanations of collective phenomena are well-founded, and when they are not.
There are two well-discussed sorts of case where intentional explanations of collective phenomena are appropriate; this paper aims to make space for a third in between them. In the simpler case, all the collective claims are read distributively, as simply summarising the mental states and actions of agents. If I say ‘the people in the park believed it was going to rain and wanted to stay dry, so they ran under the gazebo’ (example from Searle 1990), I might simply mean that each individual believed it would rain, wanted to stay dry, and consequently ran under the gazebo. On the other hand, there are cases where a group of people qualifies as an intentional agent in its own right: that is, the very same criteria of agency which apply to individuals are satisfied by the group considered as a whole (see esp. Pettit & List 2011, cf. Huebner 2014). We can then explain group actions by group beliefs and desires, which may be shared by few, or even none, of the individuals making up the group. If we say that ‘the court believed that the defendant had committed the act they were accused of, and wanted to punish such acts harshly, and so it decided to apply a harsh punishment to the defendant’, this can be appropriate even if most individual members of the court do not instantiate all of those intentional states (see List 2006).
In between these two extremes, however, there is joint intentional action: action undertaken by many people together (so it is not just an aggregate of individual actions), but which nevertheless involves no group that meets the demanding criteria for itself being an agent in the full sense. But while there has been considerable philosophical attention paid to joint intentional action (see e.g. Searle 1990, Gilbert 1990, 2000, 2009, Bratman 1997, 2009, 2014, Tuomela 2007), it remains to be shown how it can feature in intentional explanations. This is connected to the preponderance of attention given to joint intention, with much less given to joint belief, and almost none to joint desire. But intentional explanations turn on the interplay of these three types of state. I believe that by focusing on the inter-relation among these three notions, we can develop new ways to characterise joint beliefs and joint desires, which will illuminate the range of cases where intentional explanations are applicable to collective phenomena without being either merely summative or requiring full-fledged group agents. Yet in the course of developing these points, it will emerge that the groups to which they most often apply are likely to be in certain respects akin to agents – they are what I will call ‘quasi-agential’ even without being fully agents.
Section 1: Joint Mentality, Between Groups and Individuals
It will be useful to start by regimenting terminology, because so many terms in this area admit of multiple meanings. First, ‘distributive’ and ‘collective’ are grammatical modes of predication: whenever some predicate is applied to a plural term, it can be read either distributively, in which case the sentence is equivalent to a series of sentences applying that predicate to each individual member of the plurality, or collectively, in which case it is not.
Second, I will use ‘group’ for a singular entity which has many individuals as members, and ‘collection’ or ‘plurality’ as a singular term which is shorthand for plural reference to many individuals. That is, any sentence of the form ‘this collection does X’ is equivalent to a sentence of the form ‘person 1, person 2… and person N do X’ (where ‘do X’ could be read either collectively or distributively).
I will talk about group intentional states, joint intentional states, and individual intentional states: the first belong to a group in its own right, the second to a collection of individuals collectively, and the third to an individual. Individual mental states can also be ascribed by applying mental-state predicates distributively to collections. I will use the term ‘aggregate’ to signal such states: an aggregate belief is a belief that all or most individual members of some collection hold.
Distributive predications of intentional states to collections do not imply collective predications of the same state to the same collection, but they might be implied by the latter. For example, philosophers of joint intentionality disagree about whether some people having a joint intention requires that they each have a corresponding intention with the same content. We can formalise this as follows:
Distribution Principle (DP): When some individuals jointly intend (believe, desire) that P, it follows that all or most of them individually intend (believe, desire) that P.
Stronger or weaker versions of DP would involve higher or lower standards for ‘all or most’: the strongest would be simply ‘all’, while very weak versions might be 51% or more, or perhaps even less (cf. List 2014, pp.1602-1609). For convenience I will tend to speak as though the requirement were ‘all’, but plausibly it may be less than this, especially in very large collections.
Does any version of DP apply to joint intention? Bratman (2009) says yes, while Gilbert (2009, pp.171-173) says no, appealing to cases where two individuals undertake a joint action with a certain end point, but then both privately lose their resolve before reaching that end point. Gilbert thinks it intuitive that until they make this public, they still jointly intend that they complete the task even though neither individually intends that they complete the task (see Kopec and Miller ms, for criticism). I can feel the intuitive pull of Gilbert’s claim, but ultimately go with the pro-DP side. This is because the main sense in which the joint intention seems to remain, when the individual intentions are gone, is that the commitment both made to each other is still binding. In this paper I want to focus on the most basic sorts of joint agency: those that do not require hierarchies of authority, or institutional rules or procedures, or mutual obligations voluntarily entered into, and which are at work in the active, collaborative, setting up of such hierarchies, procedures, or obligations.
What about joint belief – does that obey DP? Gilbert (1994) again argues that it does not, on the basis that people may jointly believe something none of them individually believe, by feeling bound to speak and act as though that thing were true, when speaking and acting in their capacity as group members. For the same reason as above, I disagree: I want to understand the sort of joint mental states which we can attribute to people even before they start doing things like distinguishing their ‘capacity as group member’ from their ‘capacity as individual’.
A related worry is that the ‘joint beliefs’ that Gilbert describes are undertaken voluntarily and with goals in mind, which makes them less like beliefs and more like mere ‘acceptances’ (as argued by, e.g., Wray 2002). Joint beliefs governed by DP would qualify better as beliefs in this respect, since people do not choose (individually, jointly, or as a group) to have something believed by most of them. If joint beliefs (and desires) obey DP, that makes them much more similar to individual beliefs (and desires): unchosen, sometimes inarticulate, states which are formed unconsciously and manifested in a variety of behaviour, rather than actively and deliberately formed one-at-a-time. It is beliefs and desires like this which we primarily appeal to in our intentional explanations of individual actions, while consciously-formed states are more often the things we wish to explain. So in looking for the minimum preconditions for collective intentional explanations, we should focus on states which obey DP.
Section 2: Joint Belief and Desire as the Causes of Joint Intention
The following principle regarding the mental states of belief, desire, and intention seems to be a truism:
Belief-Desire-Intention Principle (BDIP): When S desires that P, and believes that doing A will bring it about that P, S will form an intention to A.
Obviously BDIP is not an exceptionless law – for one thing, S may have countervailing desires, or may not notice the relevance of their belief to their desire. But its being true for the most part is integral to how we think about these three mental states. That is, we go a long way towards explicating our notions of belief, desire, and intention just by saying:
S desires that P iffdef S is disposed to form an intention to A, whenever S believes that doing A will bring it about that P.
S believes that Q iffdef S is disposed to form an intention to A, whenever S desires that P and Q implies that doing A will bring it about that P.
S intends to A iffdef S is in a state that disposes them to A, and which they are disposed to enter whenever they desire that P, and believe that doing A will bring it about that P.
How far these three inter-definitions capture everything that is essential to these three notions is debated – for one thing, they leave out anything either phenomenal or normative. We might still say, however, that they suffice to characterise a thin, ‘functional’, notion of belief, desire, and intention. This is what Pettit and List (2010) do, and they ascribe agency to groups based primarily on their possession of states for which these inter-definitions hold (along with certain others, such as consistency of beliefs and intentions, which I will discuss in section 4).
I propose that if there are useful notions of joint desire, belief, and intention available, they should satisfy BDIP. And we have good accounts – multiple good accounts! – of joint intention. Using one of these accounts, together with the DBIP and the distribution principle, thus offers a cheap and easy way to put constraints on a useful notion of joint desire and joint belief. Namely, joint desires and beliefs are aggregate desires and beliefs together with whatever conditions are necessary to allow for the formation of joint intentions when their contents are right. More formally:
Two or more people jointly desire that P iffdef (i) each of them desires that P and (ii) they are disposed to jointly intend to A whenever they jointly believe that doing A will bring it about that P, and A is not something they can do individually.
Two or more people jointly believe that Q iffdef (i) each of them believes that Q and (ii) they are disposed to jointly intend to A whenever they jointly desire that P, and Q implies that doing A will bring it about that P, and A is not something they can do individually.
Note two shortcomings of this pair of definitions. Firstly, they are clearly dependent on one another, in such a way that it will be hard to speak meaningfully of a joint desire if we do not already have an idea of joint belief, which in turn we cannot get an idea of without some grip on joint desire, and so on. This is unfortunate from the point of view of clarity and ease of application, but it arguably corresponds to a similar holism in individual beliefs and desires. So I do not regard this as an objection to the definitions.
Secondly, as it stands these definitions are not very informative, since we have little idea what condition (ii) of each definition actually amounts to. But although the definitions do not tell us what it takes for some people to be disposed to act in the ways specified, we can look to social science and reflection on familiar social dynamics to give us some idea. Let us label the set of factors which would, in actual human societies, allow for condition (ii) in both definitions to be true, ‘corporality’ (for it allows them to desire and believe ‘as a body’). Thus joint belief and joint desire, for actual humans, are a matter of aggregate belief plus corporality, and aggregate desire plus corporality.
So what is corporality? I propose to flesh out this notion by considering ways that it might be lacking. That is, we can ask ‘under what circumstances could all members of a collection individually desire that P, and believe that doing A will bring it about that P, and know that they can only do A by working together, and yet fail to do A, not through a mere failure to execute a joint intention but through failure to form one?’ More concisely: ‘if everyone wants it, and everyone knows how they can get it, why wouldn’t they at least try?’ By seeing what factors are lacking in such cases we can build up an account of what corporality would have to be – what factors must be present to avoid such failures of collective action. Those factors will be what make condition (ii) in the above definitions true: they are elements of corporality.
In the next section I discuss three ways that collection action might fail even in the presence of aggregate beliefs and desires: by identifying the conditions for avoiding them, I develop a preliminary description of corporality. This in turn can provide an explanatorily useful conception of joint beliefs and desires, as the kinds of things that tend to lead to joint intention and thus to joint action.
Section 3: What is Corporality? Knowledge, Coordination, and Incentivisation
Joint beliefs and desires are meant to provide intentional explanations of joint action, in the sense discussed by Bratman, Gilbert, Searle, and others. This means that they must tend to produce such action when their contents rationalise it. This means that to specify what constitutes a joint belief or desire, we need to rule out cases where aggregate beliefs and desires, whose contents rationalise some joint action, might systematically fail to produce such action. So how might this happen?
I will discuss three conditions where such systematic failure might occur, all of which have been widely discussed by social scientists: ‘mutual ignorance’, ‘coordination problems’, and ‘collective action problems’. Roughly speaking, these are the cases where:
- Everyone desires that P, and believes that jointly doing A will bring it about the P, but some or all people do not know that the others desire and believe these things.
- Everyone desires that P, and believes that jointly doing A will bring it about the P, but some or all people cannot settle on mutually consistent ways of doing their parts in A.
- Everyone desires that P, and believes that jointly doing A will bring it about that P, but some or all are unwilling to do their parts in A, despite wanting the outcome, due to other desires they have.
The first of these possibilities is straightforwardly derived from the inclusion in many accounts of joint intention of a ‘common knowledge’ condition (e.g. Bratman 2009, p.157, Gilbert 2009, pp.180). If we act in ways that in fact accomplish a common goal, or even in ways that in fact depend on each other’s actions, we are still not acting together if we are ignorant of this fact. Admittedly, the exact characterisation of common knowledge is tricky (see Lewis 1969, Friedell 1969, Monderer and Samet 1988). For one thing, belief would seem as good as knowledge if our focus is on explaining what people do. To circumvent such worries, I will adopt a locution Bratman sometimes uses to express the idea behind the common knowledge condition, namely that the relevant facts should be ‘out in the open’.
Joint desire and belief require the same sort of ‘common knowledge’, because where common knowledge fails, joint action is likely to also fail. For an example of aggregate desire not leading to joint action due to a failure of common knowledge, consider five friends, each of whom wishes they would go out to the bar together (we may assume that they all have accurate beliefs about how to go to bars). But each is unaware of the other’s sharing this desire, and so nobody makes the first move and each remains at home. For an example of aggregate belief not leading to joint action due to a failure of common knowledge, consider the ‘fog of war’. Five soldiers share the desire to capture an enemy bunker, and this much is common knowledge. Each has moreover learned, independently of the others, that the bunker has a weak spot at which a few people attacking together could easily get inside, though a single attacker would fail. Because communications between them have broken down, and none knows that the others know of the weak spot, none can expect their attack to be supported and thus no attack is launched.
So common knowledge of both desire and belief are needed for aggregate beliefs and desires to lead to joint action; thus common knowledge is one element of ‘corporality’. What does deserve mention, however, is that there are two necessary components to secure common knowledge, one physical and one sociological. First, there must be means of communication available – this is what the soldiers lack. Second, people must be disposed to share information about their beliefs and desires fairly freely, and not held back by social inhibitions, or by the fear of punishment – this is what the five friends lack. So we may say: people jointly believe (desire) that P only if all or almost all of them believe (desire) that P, and they are both physically able and psychologically willing to share this information freely.
A second component of corporality comes from the requirement of what Bratman calls ‘meshing sub-plans’ (2009, p.158). Joint action requires not only that we both aim at a goal, knowing that we are doing so, but also that we be disposed to co-ordinate our efforts so as to not get in each other’s way. Consider a case where everyone wants P, and knows this, and everyone knows how they can jointly achieve P, and knows this too, but where moreover the joint action required could be done in a number of ways (at a minimum, by assigning different people to its sub-tasks), and people cannot settle on a particular way. Joint action would then not be likely, both because any actual attempt is likely to fail, with different people using incompatible methods, and because people are likely to know this and not even try as a result.
This sort of situation has been studied under the heading of ‘coordination problems’ (e.g Cooper 1998, Chwe 2001). A simple example is two people trying to meet, but not able to communicate and so unable to settle on a particular location. With larger numbers of people the options for failures of coordination are even greater, and so the ability to co-ordinate will be an important factor in moving from aggregate beliefs and desires to joint action: thus ability to co-ordinate is a component of ‘corporality’.
Like common knowledge, the ability to co-ordinate requires both physical infrastructure and certain social dispositions. We need to be able to communicate, and we need to be willing to communicate – and for some joint actions to communicate at tedious length. So we may say: people jointly believe (desire) that P only if all or almost all of them believe (desire) that P, and they are both physically able and psychologically willing to seek and settle on co-ordinated plans.
The third factor pertains not to knowledge or communication but to incentives. It might be that every individual wishes for action A to be performed, but due to their other desires some or all of them are unwilling to do their part to accomplish A. But there are actually four different types of case we should distinguish here, and only some would violate BDIP. That is, there are some ways that people’s desires might prevent them jointly acting on their aggregate desires and beliefs, which are compatible with them having joint desires and beliefs.
The relevant cases differ on three dimensions: the average strength of the aggregate desire, the connectedness or diversity of the countervailing desires, and whether the countervailing desires pertain to the object of the aggregate desire, or to the individual action it requires.
The first dimension is simple: does the collection fail to act on a strong or on a weak aggregate desire? If the aggregate desire is weak, then it is less surprising that it not be acted upon: such a case would be rather like an individual who feels a weak desire for some outcome but does not bother to act on it due to laziness, inattention, or distraction. To put it another way, one of the ways that BDIP should be qualified is to allow that a desire’s tendency to issue in intentional action is stronger, the stronger the desire is. So it is compatible with aggregate beliefs and desires being jointly held that when the desires are very weak, they have little tendency to produce joint action.
The second dimension concerns whether the reasons that various individuals have for not engaging in joint action are the same or different: when many individuals are unwilling to participate, is it just a coincidence, with them each having unrelated personal reasons, or are they all unwilling for similar reasons? To define corporality, we should look at cases where the countervailing desires are at least somewhat cohesive, because the above qualification to BDIP (that action becomes more likely as desire becomes stronger) remains true when the only countervailing desires to consider are diverse. This is because as the aggregate desire becomes stronger, it becomes statistically more and more unlikely that significant numbers of individuals have independent desires strong enough to override it. Since we are not looking for exceptionless rules but only useful generalisations, it is enough for our purposes that the likelihood of this kind of failure to act declines as the aggregate desire becomes stronger. Thus corporality need not rule out cases where the aggregate desire is very weak, or where the countervailing desires are strong and diverse.
The third dimension of variation concerns what exactly it is that individuals do not want. They may not want the outcome which the aggregate desire itself aims at – that is, they may have conflicting desires about the very same state of affairs, and the desire to avoid that outcome is stronger than the desire to achieve it. Or they may wholeheartedly desire the outcome, but dislike the steps that they individually would have to take to achieve it – i.e. each would ideally like the outcome to come about, but by someone else’s efforts. If it is the former, and if moreover the reasons are cohesive, then it turns out that one aggregate desire is being overridden by another – and this is not a violation of BDIP, which clearly ought to allow for desires to be overridden by other desires. It is only the latter case – when everyone desires the outcome, but is unwilling to bear the individual costs it requires – that corporality needs to rule out.
Cases of this sort are already well-studied, under the name of ‘collective action problems’. Their essential structure is exhibited in the “prisoners’ dilemma” (Tucker & Kuhn 1950), where two people both desire an outcome which they can achieve by both taking a certain action, but where each does better if they let the other take that action alone, and loses more from taking that action alone themselves than if neither takes it. A wide range of social problems, from climate change to consumerism, have been modelled in these terms (Cole 2008, Heath 2000). Thus part of ‘corporality’ will have to be some mechanism for solving collective action problems. Such mechanisms may either be things like legal punishments for free-riding or rewards for contributions to the collective effort, which change the decision-environment that individuals confront, or things that change individual psychology, such as inculcating a strong desire for joint actions to succeed. The various ways of solving collective action problems have been discussed at length, so I will not repeat that discussion here (though see, e.g., Axelrod 1981, Olson 1971, Ostrom 1990, 1999). So we may say: people jointly believe (desire) that P only if all or almost all of them believe (desire) that P, and they are sufficiently motivated (by whatever motives) to do their part in a joint action to achieve P.
In summary, people have a joint belief or desire when they have an aggregate belief or desire, together with at least the following three things: common knowledge of that belief or desire, sufficient ability to coordinate on the actions which it would rationalise, and sufficient incentives for individuals to willingly contribute to such actions. The first two require both physical mechanisms of communication, and social willingness both to share information and to find and accept coordinated plans. The third could be accomplished either by the inculcation of dispositions to conformity, or by skill in the provision of rewards and sanctions. There might turn out to be other requirements, but these three will suffice for now.
Section 4: Quasi-Agential Groups
Most of the elements of corporality are not specific to particular desires or beliefs. If people are in regular communication, have procedures for coordinating, and are incentivised to bear sacrifices for the sake of joint goals, then all their aggregate beliefs and desires are likely to be joint ones; if they are not, most likely none will. Thus it is useful to look not just at particular states on particular occasions, but at the group in general. A group may have more or less corporality, and so may approximate better or worse to the model of an agent as something which has beliefs and desires and can be expected to perform any action which they rationalise.
It should not be thought that corporality is hard to establish. The physical conditions that enable coordination and commonality of knowledge can be established simply by spatial proximity, and the psychological conditions for these things, and for individual willingness to make costly contributions, can be established by the normal psychology of social relationships (see e.g. MacMillan & Chavis 1986). If a hundred people live in the same village, with regular communication, mutual concern, and a willingness to work together, then they might well show a high degree of corporality, so that whatever beliefs and desires were aggregate would be liable to lead to joint action, and thus jointly held. Obviously, corporality in larger groups will be harder to achieve, and formal institutions (e.g. chains of command) and ideologies (e.g. nationalism) can be seen as partly aiming to render larger groups more corporal than they would otherwise be.
High levels of corporality make a collection of people operate in some respects like an agent, in that some but not all of the defining principles of agency hold of them collectively. What does hold is BDIP: they will tend to act (jointly) whenever it is rationalised by their (joint) beliefs and (joint) desires. What does not hold of them is, firstly, consistency: it is not true that they will generally have only consistent sets of (joint) beliefs or (joint) intentions, or that when they have inconsistent (joint) beliefs or (joint) intentions they will take steps to correct this inconsistency. Another way in which they are not fully agential is the lack of scope of their attitudes: on any topic where many of the individuals disagree, they will neither jointly believe P nor jointly believe not-P, or neither jointly desire that P nor jointly desire that not-P. If they have little agreement, then they may have so few joint beliefs and desires that rationalising explanations only rarely make useful predictions.
These two failings are inversely related: the more we allow ourselves to say that people have a joint belief (say) even when they are not unanimous, but merely show some strong majority opinion, the more easily will inconsistencies arise, while if we try to rule out inconsistencies by insisting on unanimity, the fewer will be the joint states we can posit. This is (a simplified version of) the ‘discursive dilemma’ (List 2006, cf. Arrow 1950), which Pettit and List use to show that even weak versions of the distribution principle must fail when we are dealing with genuine group agents.
I will use the term ‘quasi-agential’ for groups whose members have both high corporality, and high agreement in beliefs and desires (i.e. a high proportion of individual beliefs and desires are ‘aggregate’, shared by many individuals). High corporality ensures that beliefs and desires which are aggregate will be jointly held, while high agreement ensures that there will be enough aggregate beliefs and desires to underwrite a range of interesting predictions. Quasi-agential groups are not group agents, but they are a natural precursor, since their propensity to joint action will both motivate steps to prevent contradictory beliefs and intentions (which would lead to self-defeating actions), and allow them to set up measures to do this which will have enough support and participation to work. Quasi-agential groups are fertile ground for the creation of agential groups, and thus provide a fertile conceptual link between joint agency and group agency.
At the same time, quasi-agential groups allow for explanations at a collective level that are relevantly and usefully different from explanations at an individual level. This is not because an explanation purely in terms of individuals could not be given: I think it could in principle, just as my every move could in principle be predicted by a neuroscientifically-omniscient person with superhuman calculating abilities. But just like the best higher-level explanations, explaining that some people did something jointly because they jointly believed that it would bring about something they jointly desired provides elegance and unity by abstracting from irrelevant details. This is true particularly because so much of the individual-level explanation would have to mention each individual’s beliefs about and attitudes towards the other individuals, who in turn had complex beliefs and attitudes concerning the others, and so on in a web of relations that would be grotesquely complicated to spell out in detail. It is an advantage to cut past those multiple looping feedback relations by saying that the group involved satisfied certain group-level conditions, such as those comprising what I have labelled ‘corporality’.
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 List 2014 distinguishes a form of group attitude that is more than just a summary but less than a group agent’s attitude, namely a ‘common attitude’, which is a widely shared attitude whose wide sharing is common knowledge among those who share it. As he argues there, common attitudes are a precondition for many forms of joint action: my notion of a ‘joint attitude’ is stronger yet, in aiming to be a predictor of joint action.
 Indeed, Gilbert’s account of joint intention makes joint commitment central, and the account has in consequence been accused of circularity: to intentionally do anything jointly requires first jointly committing, but committing is presumably something that must be done intentionally, so doing it jointly seems to require a prior joint commitment, which in turns requires another, and another, and so on (cf. Tollefsen 2002).
 It should be emphasised that P is to be understood as a non-indexical content. If everyone’s desire is that “I get the cake”, they do not desire the same thing – rather, they each desire something different. They would each desire the same thing if there was a particular person who they each desired to get the cake.
 I will discuss condition (ii) of both definitions together, since I believe that they will be satisfied by roughly equivalent factors.
 For another thing, common knowledge sometimes seems to have an indefinitely iterated character: I know that you want it, and I know that you know that I know that you want it, and I know that you know that I know that you know that I know that you want it… But it’s not clear we should include this as a requirement: if two people can have iterated knowledge of the other’s knowledge up to the third level, that would seem to be enough for practical purposes.
 I believe a similar requirement is implicit in Gilbert’s requirement that to jointly intend some action we must strive “as far as possible to emulate, by virtue of the actions of each, a single body that intends” that action (2009, p.180).
 Institutional procedures of coordination, like division of labour or a chain of command, might be thought of a ‘stored’ deliberation, in that they allow for a particular coordinated action based not on everyone thinking about and agreeing to that particular plan of action, but on everyone having thought about and accepted the institutional procedures at various earlier times.
 This is certainly not an exceptionless rule. For instance, a collection of people might observe taboos about talking publicly about certain topics, with the result that aggregate desires pertaining to those topics were not common knowledge, and hence not joint desires, while aggregate desires pertaining to other topics were. To this extent the discussion here, in which corporality is equal for all aggregate states, represents a simplification. But I believe it is a simplification much less distorting than the opposite simplification, of assuming that corporality for any particular aggregate state is independent of corporality for any other.
 Another aspect of agency is the tendency for beliefs to be responsive to evidence: if beliefs have no correlation with the truth of their contents, it is less clear that they are really ‘functioning as beliefs’. By and large aggregate beliefs will tend to be as evidence-responsive as the individual beliefs that constitute them (a joint belief ‘an earthquake is happening’ might be responsive to evidence because it arises only when an earthquake is happening, because individuals will only believe that en masse when an earthquake is happening). But divergences are entirely possible: a group in which people with a track record of being right are more likely to be talked with would be more evidence-responsive than a group where such people are shunned for being ‘know-it-alls’, even if the average evidence-responsiveness of each individual member is the same. The precise way to spell out the requirement of evidence-responsiveness is of course complicated by the difficulty of saying what counts as ‘evidence’ at the collective scale: in this paper I do not attempt to address this interesting question.
 Pettit 2007 speaks in a similar way of ‘embryonic group agents’, but this is simply a pragmatic category: they are groups which it would be useful for us to treat as agents, in the hope that they will incorporate themselves and become agents. It is not an intermediate level of intrinsic intentional functioning, as is my notion of a quasi-agential group.