GROUP AGENTS AND
COLLECTIVE INTENTIONS
Raimo Tuomela
University of Helsinki
University of Munich
Individualism in Social Science
(a) Conceptual understanding of an individual’s action
must be based on either the individual’s own attitudes or
reasons or some other agent’s (individual’s or reducible
group agent’s) attitudes and reasons as its ground.
(Meaning)
(b) Explanation of an individual’s action must have
either the individual’s own attitudes and reasons or some
other agent’s (individual or reducible group agent’s)
attitudes and reasons as its explanatory basis.
(Explanation)
(c) The basic ontology of the best explaining social
scientific theory must consist solely of the activities and
properties and interactions of either individuals or
groups reducible to the individualistic basis referred to in
(a) and (b). (Ontology)
Why we-thinking?
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We-thinking in the full we-mode sense is
in some cases conceptually necessary, e.g. in contexts where
the we-mode constitutes (and thus constructs) full-blown group
notions—collective artifacts—such as group beliefs or social
institutions;
functionally required in many contexts, especially in cases of joint
action requiring synergy effects for collectively (and individually)
beneficial results.
theoretically sufficient for (dis)solving central collective action
dilemmas (e.g. the PD) and thus for creating collective order.
needed for group-based cultural evolution in “developed” cases.
is capable of handling large groups better than the I-mode
(primary dependence concerns the group and not individuals).
We-mode group
A person functions in the we-mode if she functions as a
group member (in a strong sense) and in the I-mode if
she functions as a private person, possibly in a group
context.
A group is in most contexts below assumed to be a wemode group (a species of corporatio). It is assumed to
commit itself to a group ethos (certain constitutive goals,
beliefs, standards, norms, etc.) and to relevant wereasoning and we-acting. A we-mode group constructs
itself as a group in a quasi-entifying sense and can be
viewed as a functional group agent.
Because of group membership the members of a wemode group ought to act as group members and thus to
“identify with the group”.
History 1:
Group minds and group agents
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Group minds and agents have been discussed for
thousands of years.
The ancient Romans built into their law the idea of
corporate responsibility, speaking of organized
collectives that were also referred to by the terms
“universitas”, “corporatio,” and “collegium”.
A corporation (corporatio) contrasts with “societas,” a
collective based on interaction of individuals who do not
form an intentional group agent or a “group person”
(where the term “person” indicates a theatrical mask).
A corporatio is a persona capable of action and of
making promises and fulfilling them (Hobbes).
History 2:
Accounts of group minds and group agents
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Intrinsically intentional group agents: groups are
intrinsically intentional analogously with the
intentionality of individual agents.
Extrinsically intentional group agents: group
members form the group mind (collective attitudes,
etc.) e.g. by their relevant kind of collective
acceptance or some related group-internal process
or mechanism.
Group Agents 1
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An organized group (e.g. a we-mode group) can
functionalistically be taken to be an agent (person) if it is
goal-directed and if it can also be taken to reason and
even reflect upon its activities. Its mental states are
functionalistically construed as group-level states.
In simple cases, a group agent is (possibly “emergently”)
constructed on the basis of individuals’ properties and
relations. In the case of corporations and states and
other group agents with normatively characterized
positions a more top-down kind of construction is
typically used. We thus have a group-level description of
collective intentions and beliefs, etc. and a member-level
description of them.
Group Agents 2
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A group agent exists as a functional social
system capable of producing uniform action,
not as an intentional agent with phenomenal
features. It can only function via its members’
functioning appropriately. In many cases a
group agent involves some fictitious and
irreducible constructive elements and cannot
be fully accounted by individualism.
Three central we-mode criteria
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The we-mode involves the following three central ideas
on the member level (Tuomela, The Philosophy of
Sociality, Oxford UP, 2007 and Tuomela (forthcoming)):
(authoritative) group reason,
collectivity condition, and
collective commitment.
We-mode mental attitudes are had in the way or
mode satisfying the above requirements for thinking
and acting with the full we-perspective with a
“togetherness-we”. People can e.g. carry a table
either in the I-mode or in the we-mode. A content
can in this sense be intended in various modes.
I thinking and we-thinking in the I-mode
versus the we-mode 1
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In general, there can be we-thinking and
action, etc. in the we-mode and we-thinking
or action in the I-mode (even for the benefit of
the group’s goals and interests).
On the other hand, there can be I-thinking
and action in the we-mode (conceptually
group-dependent thinking, e.g. I we-intend to
participate in joint action) and in the I-mode
(“private” I-thinking without conceptual
dependence on the group).
I thinking and we-thinking in the I-mode
versus the we-mode 2
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The above classification can be presented concisely in terms of
symbols as follows, where e.g. J = carrying a table jointly:
(1) IM(I, PJ)
(2) WM(I, PJ)
(3) IM (W, J)
(4) WM(W, J)
Here IM and WM are operators covering the contents within the
parentheses. I and W respectively mean I-intention and weintention where the mode of the we-intention determines in which
way or manner the content is held and in the case of WM the
“strength” of the “we” involved in it. J means joint action as the
content of a we-intention and PJ an individual member’s part
action in the members’ joint performance of J.
An argument for the central we-mode criteria
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The idea of a group agent capable of acting as a group
can in part be based on an intuitive analogy of intentional
action (as action for a reason) in both the individual and
the group case. Analogously to typical intentional action
by an individual agent, intentional action by a group
agent (and its parts, the members) is normally based on
reasons for actions. Analogously to an individual’s
having to coordinate the movements of her body parts,
the members of a (we-mode) group coordinate their
activities (including mental ones) in order to achieve
group goals. Analogously to an individual agent
committed to her intended actions, the group members
are committed as a group, i.e. collectively committed, to
the group's actions.
We-mode versus I-mode: functional
differences
One of Bacharach’s (1999) results can be applied to show that the
(pro-group) I-mode and the we-mode, probabilistically construed
concerning mode adoption, do not entail the same equilibrium
behaviors. This holds also for cases (even) where the choices,
utilities and the probabilities of the players acting for their own
benefit instead of the group’s benefit are the same: The pro-group Imode admits Pareto-suboptimal equilibria (e.g. DD in Hi-Lo) that in
many cases will not be equilibria in the we-mode case.
The above applies especially to common interest (Paretian) game
situations with strong interdependence (such as, the Hi-Lo game
and the PD).
In Hi-Lo a full-blown group “framing” obviously makes joint outcome
Hi-Hi (rather than Lo-Lo) a rational group’s choice.
II
COLLECTIVE INTENTIONS
Joint intentions, we-intentions, and group
agent’s intentions
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Collective intentions in this talk include joint intentions,
we-intentions, and group agents’ intentions.
One can act jointly either on an I-mode joint intention or,
in a conceptually and functionally stronger sense, on a
we-mode joint intention. We-intentions are components
of joint intentions. In addition also intentions attributed to
groups qua collective intentions will be discussed. All
these three kinds of collective intentions are closely
interconnected.
In some agents’ we-mode joint action the agents form a
we-mode group even in fleeting cases.
I-mode intention
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(IMI) Agent A has the intention that P in the I-mode
if and only if A is privately committed to satisfying P
(or participating in satisfying P) and he intends to do
it at least in part for himself qua private person
(rather than qua group member).
(PLIMI) Agent A has the intention that P in the plain
I-mode if and only if A is privately committed to
satisfying P (or participating in satisfying P) and he
intends to do it only for himself qua private person.
Pro-group I-mode intention
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(PROGIMI) Agent A has the intention that P
in the pro-group I-mode in group g if and only
if A is functioning qua member of g (in a weak
sense), A is privately committed to
participating in satisfying P and he intends to
do it at least in part for the members of group
g but in part for himself qua private person.
We-mode intention
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(WMI) Agent A has the intention P in the we-mode in
a group, g, of agents if and only if
(i) A is functioning qua member of g,
(ii) the intention toward P is based on or at least
compatible with what has been collectively accepted
for g by the agents,
(iii) A intends to participate in the satisfaction of
intention P for g, and
(iv) the criteria of group reason, collectivity, and
collective commitment are satisfied for the agents.
Collectivity, collective commitment, and
group reason
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Collectivity condition for intention: On the ground of (ii), it is
necessary that the intention is satisfied for A if and only if it is
satisfied for other group members sharing it.
Collective commitment in the we-mode case:
(i) We-mode collective commitment is based on a group reason, viz.
a reason for the members to participate -- as distinct from a group
agent’s reason to act.
(ii) Giving up one’s commitment here generally requires the group’s
permission.
(iii) In the plain or mere I-mode case a person is committed to
herself to furthering her own interests. In the pro-group I-mode case
she is committed to herself to furthering, at least in part, the group’s
interests. In the we-mode case she is committed to the group to
furthering the (we-mode) group’s interests.
Core joint intention
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Some participants’ joint intention consists of interdependent
member intentions (we-intentions) all of which are also
expressible by “We will do X together.” I regard the notion of a
we-mode joint intention as a conceptually primitive notion, one
that prima facie is not reducible to individuals’ mental states
without invoking the notion of agentive social group.
The core idea in my view of joint intention is that if we, viz. you
and I qua members of g, jointly intend to perform X together, this
requires that you and I both intend to participate in our
performing X jointly for us and do it qua members of g and being
collectively committed to performing X jointly; and you and I
mutually know (or correctly believe) all this.
Plan acceptance and joint intention
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(PJI) Some agents (say, A1,…,Am) have formed the joint
intention to perform X if and only if (a) each of them has
accepted a plan to perform X jointly, (b) each of them has
communicated this acceptance to the others, and (c) it is a true
mutual belief among A1,…,Am that (a) and (b) and that they are
collectively committed to performing X and that there is or will be
a part or share (requiring at least potential contribution) of X for
each agent to perform that he accordingly is or will be committed
to performing.
On the right-hand side of the analysis, mutual acceptance need
only amount to “coaction” that falls short of collectively intentional
joint acceptance that would make the account directly circular.
Joint intention further clarified
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If the members of a group collectively accept the
truth (correctness) of “We will do X together as a
group”, this understood as a conative expression
with the world-to-mind fit, and if the central we-mode
criteria of group reason, collectivity, and collective
commitment are satisfied, then and only then they
jointly intend qua group members to perform X
together as a group.
Given this view, what will be said of we-intentions
below, in view of the idea that we-intentions are a
kind of slices of joint intentions, will also give more
information about the notion of joint intention.
We-mode we-intention in joint action
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We-mode intentions need not always concern joint action in a
specific sense but in general the group members’ activities as group
members in a group. Note that The agents to which we-mode
intentions can be attributed can also be group agents, e.g. the
member states in the EU. Accordingly group agents’ interaction and
interdependence features (e.g. cooperation, conflict) can be
investigated within this framework..
In the the case of a specific joint action such as painting a house
together a participant A can be said to we-intend to perform an
action X with the other members – linguistically, to accept the truth
of “We will do X together, as a group”.
The notion of we-intention is analyzed below. It can be seen to
satisfy the three central we-mode criteria of group reason,
collectivity, and collective commitment.
An account of we-intention
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(WI) Member Ai of group g we-intends to perform X together as a
group with the other members if and only if
(i) Ai intends to participate in the members’ (“our”) doing X together
and to do his part of X as his part of X;
(ii) Ai truly believes that the group members (including himself)
collectively accept “We will do X together as a group” in that context
and that thus a joint intention to perform X jointly exists between the
participants, and this fact is his main justificatory reason for (i);
(iii) Ai has a true belief to the effect that the joint action opportunities
for an intentional performance of X will obtain;
(iv) Ai truly believes that there is (or will be) a mutual belief among
the participating members of g to the effect that the joint action
opportunities for an intentional performance of X will obtain;
(v) (i) and (ii) are in part true because of (iii) and (iv).
Reasoning schemas constitutive of we-intending
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(W1)
(i) We will do X together.
(ii) I am one of “us” (the present group).
Therefore,
(iii) I will do my part of our joint performance of X.
(W2)
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(i) We will do X together.
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(ii) X cannot be performed by us together unless we perform action Z (e.g.
help or teach a group member to do his part)
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Therefore,
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(iii) We will do Z.
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(iv) Unless I perform Y we cannot perform Z.
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Therefore (because of (iii) and (iv)),
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(v) I will do Y (as my contribution to Z).
(W1) expresses group membership, (W2) collective commitment and helping.
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I-mode joint intention
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(IMJI) You and I share in the I-mode the intention to perform X jointly
if and only if
(1) I intend that we X in the external reason-based we-attitude sense
(namely, I intend that we X in part because I believe that you intend
in the external reason-based sense that we X and that we mutually
believe that each of us so intends), and
(2) you similarly intend that we X in the external reason-based weattitude sense,
(3) it is mutually believed by you and me that (1) and (2).
External reasons above are contingent (as contrasted with
conceptually required) reasons for one’s intention as explained in
Tuomela (2007), Chapter 4. Bluntly speaking, the other persons and
their intentions are taken to be a contingent part of the intender’s
environment conducive to his own purposes.
Group agent’s intention 1
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Finally, a (we-mode) group’s intention to see to it
that something X will be the case is based on its
members’, or at least some members’ relevant
joint intention. In simple, e.g. egalitarian, cases
this kind of account creates a group-level
attitude on the basis of member-level attitudes.
Here members’ having a joint intention is
normally truth equivalent with the group’s having
the intention with that content.
The other members because of their
membership ought to accept what the operatives
have accepted as the group’s intention, all this in
conditions of mutual knowledge.
Group agent’s intention 2
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(GI) Group g intends to see to it that X obtains (or comes about, etc.,
where X is an action or state) as a group if and only if there are
operative members of g such that
(1) these agents, when acting as group members in the we-mode or in
the quasi we-mode sense, have the joint intention toward X (e.g.,
involving acceptance of the conative expression “Our intention as a
group is to see to it jointly that X” or one of its cognates for g) and are
collectively committed to bringing about X;
(2) there is a mutual belief among the operative members to the effect
that (1);
(3) because of (1), the (full-fledged and adequately informed)
nonoperative members qua members of g tend (explicitly or implicitly)
to accept with collective commitment—or at least group-normatively
ought so to accept—that their group g intends to perform X (as
specified in clause (1));
(4) there is a mutual belief in g to the effect that (3).
Groups with differing psychologies
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We may note that—compatibly with (IG)—corporations
(e.g. business companies) can in real life operate on the
basis of different kinds of “psychologies”, so to speak.
There can be we-mode thinking and acting, I-mode
thinking and acting, or some kinds of mixtures of these.
In this sense on the group level there may be
independence of psychological mode.
Above only “we-mode guided” cases where at least the
leaders are assumed to function in the we-mode and
thus for the group in a strong sense. Especially, progroup I-mode guided cases are possible, but overall the
we-mode way of operating tends to lead to collectively
better results.
Levels of we-mode collective intention: an
example
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(a) Group g intends to paint the house. (Group intention):
(b) We (the members of g) accept collectively (in an explicit or
implicit sense) that we will paint the house jointly and hence
accept as true for g the intention expression “We will paint the
house jointly.” (Joint intention)
(c) Each of us accepts the intention expression “We will paint the
house jointly.” (We-intention)
(d) I, qua member of g and a participant in our joint intention to
paint the house jointly with the others, intend to perform my part
(or contributory share) of our painting the house. (Generic partperformance intention; the central intention-component of a weintention)
(e) My part being to paint the front of the house, I intend to do it
and set myself to do it. (Specific part-performance intention
followed by intention-in-action that initiates action)
Group reasons as coordinating collective
activities
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The fact expressed by (a) may be a social, coordinative group
reason for (b) when (a) is conceptually and justificatorily prior to
(b)—such as it is e.g. in the case of a leader’s order entailing (a)
given that (a), furthermore, is collectively accepted by the
members. In simple egalitarian cases without delegation of group
tasks to specially authorized members (a) and (b) can be
regarded as truth-equivalent.
(b) expresses a social, at least coordinative reason for (c), (c)
entails (d) on conceptual grounds, and (d) entails (e) on
conceptual and situation-specific informational grounds. In the
sense of this schema group reason requires acting at least partly
for the group.
The group reason for members’ participation expressed by (a)
serves in this context as the central explanans of (e).
III
SOME HISTORICAL ACCOUNTS OF GROUP
AGENTS AND COLLECTIVE VOLITIONS
Collective will a century ago and now
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About a century ago many group phenomena were
discussed that current collective intentionality and social
ontology discussions also are concerned with, though in
a more sophisticated way.
These early theoreticians in effect made basically the
distinction between individualistic and collectivistic
thinking and acting that I have called the pro-group Imode versus we-mode thinking and acting. This is
interesting, as modern literature on collective
intentionality with the exception of my recent work does
not discuss this distinction and its significance.
Collective will a century ago and now (cont’d)
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In my 2007 book the grand research theme is the progroup I-mode / we-mode distinction and its functional
effects. In 2007 came upon game theoretician Michael
Bacharach’s posthumous 2006 book and read his 1999
paper on team reasoning. That paper in effect makes the
distinction between the pro-group I-mode and the wemode in a game-theoretic context and shows their
functional differences concerning action equilibria in
certain game-theoretic contexts (see also Hakli et al.,
2010). The we-mode entails fewer equilibria than the
pro-group I-mode in the case of some dilemma cases.
The distinction between pro-group I-mode and we-mode
cases was in a rudimentary sense considered by at least
McDougall and Vierkandt but was then forgotten.
McDougall on collective volition
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McDougall (1920) considers a group of pilgrims on their way to a city
and discusses the following five cases of increasing strength:
1. Impulsive collective action: Robbers attack a group on its way and
the members of the group flee in panic.
2. In a stronger case, the individual wills are strengthened by the
“community of purpose.” There is no collective volition here, and the
action is not due to the will of all. The members do not at all care for
the arrival of the group as a whole; they desire and will only their
own arrival. This is a case of plain I-mode intention and action.
3. In the next case, it is assumed that the group members are aware
of the danger of robbers and that the group will need its full strength
for its members not to get robbed. Each member privately desires
that the whole group shall reach the city. This is not truly a
collective volition because the individual desires (volitions) are
private and diverse. This is a case of the pro-group I-mode.
McDougall on collective volition (cont’d)
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4. In the next case, the group is taken to be an army of crusaders
composed of various nationalities: all members will the same
collective action and desire the same end of that action, and they
also have similar motives arising from their “sentiment for the city”.
Still their combined actions are not due to a collective volition but
only a coincidental collection of individual volitions. This is a
(strengthened form of) pro-group I-mode intention and action.
5. In the strongest case the crusaders are of the same nationality
and each member identifies himself with the army and desires its
success as an end in itself. Here we have collective will: The
participants with the same cultural and social background share an
underlying motive (sentiment) and desire to achieve the same end.
The participants identification with the group in the context of their
shared sentiment and desire makes them intend (will) and act as a
group. This is a strong kind of we-mode case of a group’s intention
and of its members jointly intending as a group.
Vierkandt on groups and group will
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Alfred Vierkandt’s theory in his book
Gesellschaftslehre (2nd ed.) of 1928 contains
interesting accounts of group life.
Vierkandt postulates a group agent in a subjective
sense—the group seems to its members to be an
objective (super)agent without really being one. He
argues that a “we” is needed for analyzing the group
and group will. A group will is a will that is active in
all members (or at least in the authoritative and
leading members) and that the members experience
it as “our” will.
Vierkandt on group will (cont’d)
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Vierkandt distinguishes between a will that is shared (“gemeinsam”)
and one that is “societal” (“gemeinschaftlich”) on McDougallian lines.
Vierkandt’s societal will or intention is a rudimentary version of a wemode group intention and his shared intention amounts to pro-group
I-mode intention.
Example: When some people aim at shooting at an escaped lion
they may just do it together (gemeinsam) based on their personal
(private) “affect” while having the same object (the lion) as the
physical object of the shooting and while coordinating their activities
appropriately. This seems to be pro-group I-mode willing and
shooting—the subjects are different and there is no group will.
But when they (like an army unit would do) form their will and act on
it as a group, also the subject is the same, viz. the group. The
societal (gemeinschaftlich) case covers organized groups that can
be viewed as group agents. We have a we-mode case here.
Tönnies on collective volition (will)
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Ferdinand Tönnies published the first edition of his wellknown book Gemeinschaft und Gesellschaft
(1887/1996). In his late 1931 paper, entitled
“Gemeinschaft und Gesellschaft” as well, he makes
some new points.
He postulates an artificial, imaginary collective person, a
kind of plural agent consisting of persons, as a carrier of
the collective will that also is needed for unifying the
group.
The collective person unifies its members not only by
making them factually dependent on the basis of their
knowledge of the shared collective will but also
normatively dependent, for the collective will is supposed
to give the participants relevant rights and duties
(interpersonal social commitment ensues).
Tönnies on collective will (cont’d)
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“If the volition of the one [person] meets and combines with the
volition of the other, there results a common volition which may
be interpreted as unified because it is mutual. This common
volition postulates or requires, and thus controls, the volition of A
in accordance with the volition of B as well as the volition of B in
accordance with the volition of A.” “…thus, the will of each single
person who belongs to the group is part of and at the same time
conditioned by the group’s collective will, which is to say he is
dependent on it.” “Every collective will can represent itself in a
single natural person or in a number of those whose common will
is conceived as the representation of a higher collective will.”
References
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Bacharach, M. 1999. “Interactive Team Reasoning: A Contribution to
the Theory of Co-operation”, Research in Economics 53, 117-147.
Hakli, R., Miller, K., and Tuomela, R. 2010. “Two Kinds of WeReasoning.” Economics and Philosophy.
McDougall, W. (1920). The Group Mind. Cambridge: Cambridge
University Press.
Tuomela, R. (2007). The Philosophy of Sociality: The Shared Point of
View, New York: Oxford University Press. (Paperback ed. 2010).
Tuomela, R. (forthcoming), Social Ontology: Collective Intentionality
and Group Agents, Oxford University Press
Tönnies, F. (1887/1996). Community and Society (Gemeinschaft und
Gesellschaft), New Brunswick, NJ: Transaction Publishers.
Vierkandt, A. (1928/1975), Gesellschaftslehre, 2nd Ed. New York: Arno
Press
We-mode versus I-mode intentions and
social action
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The following cases of social action in a multiagent context are at
least conceptually possible while any other combinations of the
basic elements involved are conceptually excluded:
(1) An agent has an I-intention in the I-mode to perform an action Y
as his participatory action in an action X performed jointly in the Imode;
(2) An agent has an I-intention in the we-mode to perform an action
Y as his participatory action in an action X performed jointly in the
we-mode;
(3) An agent has a we-intention in the I-mode to perform an action X
jointly with some others in the I-mode;
(4) An agent has a we-intention in the we-mode to perform an action
X jointly in the we-mode with some others.
The restriction to a multiagent context in this classification excludes
single-agent action that has a social reason (e.g. somebody drives a
sports car because all cool guys do it, etc.) and also group agent’s
action (see below in the text).
A general argument for the satisfaction of the three wemode criteria in the case of organized groups 1
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(1) A we-mode group can perform intentional actions (at least in
a functional sense).
(2) Intentional action requires an agent, an individual agent or a
group agent, respectively, in the individual case and the group
case.
(3) Intentional action by an individual agent and by a group agent
are relevantly analogous concerning the central features of the
common sense conceptual framework of agency (cf. premise (5)
below).
(4) Intentional action requires that the agent acts for a reason, is
committed to the action, and appropriately coordinates the
activities and movements that the performance of the action in
question requires.
A general argument for the satisfaction of the three wemode criteria in the case of organized groups 2
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(5) On the basis of (3) and (4), intentional action by
a group agent requires that the group acts for a
unitary reason, is committed to its activities and
coordinates the activities and movements that the
performance of the action requires.
(6) A group acts (and can only act) intentionally
through its members (acting as group members).
(7) Acting as a group member in the full sense, viz.
in the we-mode, requires acting for a group reason,
satisfying the coordinative collectivity condition, and
the member’s taking part in the participants’
collective commitment to the joint action (a part of
which an individual member is performing).
The centrality of joint intention 1
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1) Joint intentions figure centrally in participants’ (social) practical
reasoning and resulting joint action. Thus:
a) Joint intentions - in analogy with single-agent intentions - present
problems and restrict available action alternatives. E.g. forming a joint
intention to go swimming excludes other alternatives and pre-sents
problems concerning the means to perform the joint action in question.
b) Joint intentions serve - in the “jointness” sense - to initiate, guide,
control, and monitor joint action, creating order - especially
interpersonal coordination - in social life. Furthermore, there cannot be
intentional joint action without joint intention (at least joint “intention-inaction”).
c) Joint intentions help to connect the group-level with the personal
level. Thus it can be argued that a group’s intentional action - e.g., a
business company’s buying another company - must be based on the
joint intentions of some authority-possessing members of the group.
d) Joint intentions have a normative impact on the agents’ thinking and
acting.
The centrality of joint intention 2
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2) The concept of joint intention is central both in philosophy of social
science and in theorizing about the social world.Thus:
a) The concept of joint intention (a person’s we-intention) is needed for
a satisfactory characterization of the social “I” (viz. “I” as “one of us”). It
will argued below that joint intentions - which are necessary ingredients
of intentional joint action – arguably are conceptually and ontologically
irreducible to private intentions and other private notions.
b) The concept of joint intention helps to conceptualize the conflict
between the group-level and personal level interests and is central for
the analysis of group-phenomena such as actions performed by groups
in terms of what group members think and do;
c) The notion of joint intention (and related jointness-notions) can be
and should be important in theory-formation in the social sciences. The
most basic argument for this is simply that people have joint intentions
in many central social situations and that, therefore, social theory must
deal with the concept of joint intention.
d) The notion of a joint intention entails joint commitment, which is at
least a weakly normative notion.