We believe that philosophical progress is best achieved through the statement of sharply defined positions which are then contested in robust debate. We expected our arguments to be controversial, and we are pleased that they have been examined so carefully by two writers whose work has influenced our own. Before replying to their comments, inevitably emphasizing differences between our respective positions, we wish to acknowledge the extent to which Benedetto Gui and Julie Nelson are engaged in the same enterprise as we are. We all share the belief that market relationships can, and often do, involve genuine sociality of a kind that is not represented in traditional economic theory. What is at issue between us is how that sociality should be understood.

We sense that Nelson is particularly unhappy with our characterization of her approach as ‘another reworking of the market/social opposition’. Perhaps that wording was unclear, but we were trying to express what we still believe to be a significant difference between her approach and ours. She is right to say that her work rejects the hypothesis that real market relationships are asocial. However, it retains a distinction between the self-interested motivations that economists have traditionally used to explain market behaviour and an array of other-regarding and ‘intrinsic’ motivations that, equally traditionally, have been thought to belong to a separate domain of social life. Nelson's approach does not resolve the opposition between these two types of motivation; instead, it understands behaviour in markets as exhibiting a mixture of them.

This idea of a mixture of motivations is well expressed in the title of the paper that Nelson wrote with Nancy Folbre, and to which Nelson refers: ‘For love or money – or both?’ (Folbre and Nelson, Reference Folbre and Nelson2000) The suggestion is that behaviour in markets is partly self-interested (‘for money’) and partly other-regarding (‘for love’). The same idea appears as the fear that care providers ‘may be motivated only by the reward of a paycheck’, the corresponding hope being that their self-interest will be mixed with a sufficiently strong ‘concern for the well-being of the recipient’. It appears again in Nelson's suggestion that real markets have ‘dimensions of provisioning, relationships, and incomplete commodification’. Notice how Nelson treats ‘relationships’ as a dimension of markets; the implication is that this is distinct from the instrumental dimension of self-interested exchange. In contrast, our account of the sociality of market relationships is based on a single motivation – joint commitment to mutual assistance, modelled as team reasoning. The motivations that Nelson mixes are the motivations of individuals, even though some of them have other-oriented, pro-social or non-instrumental content. Our analysis differs by using a relational rather than individual concept of motivation, represented as the jointness of actions and intentions. Relationality in this structural sense, rather than any particular content of motivations, is for us the essential characteristic of sociality.

We claim that this kind of joint motivation belongs to neither component of Nelson's mixture. Nelson disagrees, arguing that it can be expressed equivalently as an intrinsic motivation. She maintains that our characterization of intrinsic motivation, while consistent with the definition given by Richard Ryan and Edward Deci, does not correspond with her own, less individualistic interpretation of the concept. We accept this, but we are not convinced that intrinsic motivation, as understood by Nelson, can have the relational content of a joint commitment to mutual assistance.

Following Bruno Frey, Nelson treats a motivation as intrinsic if it is not a response to ‘monetary payment’ or ‘command’, and if it is ‘self-determined’ or ‘internally generated’. This definition can include both the enjoyment of an activity in itself (which Ryan and Deci would classify as an ‘intrinsic’ motivation) and other-oriented motivations with which the individual freely identifies (which Ryan and Deci would classify as ‘internal’ but ‘extrinsic’). But notice how, here and throughout Nelson's discussion, concepts that are associated with economic exchange (‘money’, ‘payment’, ‘paycheque’, ‘commodity’, ‘wealth’) are consistently aligned with non-autonomous motivation; the pursuit of economic ‘reward’ is classified in the same way as acting on a command. Although ‘relatedness’, ‘relationships’, ‘community’, ‘affiliation’ and so on repeatedly appear as objects that might be sought by autonomously motivated individuals, the literature of intrinsic motivation seems unable to make sense of the idea that the achievement of mutual benefit through exchange might be the content of an authentic relationship. The implication is that the ordinary economic transactions on which we all depend for our survival are somehow inauthentic. Whether this attitude is interpreted as a romantic yearning for a lost Rousseauian age of economic innocence or as a disturbing alienation from real life, it is not one that we share.

We do not deny that, in principle, the concept of intrinsic or internal motivation could be expanded to include joint commitment to mutual assistance. But that would be possible only by removing the substantive psychological content of Ryan and Deci's analysis and substituting that of ours; and that would make ‘intrinsic motivation’ an empty formula. A similar response can be made to Gui's claim that team reasoning can be represented ‘in the language of individual motivation’ by using Amartya Sen's concept of commitment. Gui agrees with us that altruism, reciprocity (as modelled in Matthew Rabin's theory of ‘fairness’) and inequity aversion – the most common ingredients in theories of social preference – differ from team reasoning by treating sociality as self-sacrifice. However, he proposes to model a commitment to team reasoning either as guilt aversion (a utility penalty for deviating from that commitment) or as warm glow (a utility premium for upholding it). But guilt aversion and warm glow are not substantive psychological motivations in the sense that altruism is; they are only placeholders for an unspecified theory which describes the kind of attitude or action to which the individual is committed. Any theory of behaviour can be re-described in this way, but nothing seems to be gained by doing so. For example, think of conventional consumer theory, in which the individual maximizes the value of a function defined on commodity space. Why not replace this with warm-glow consumer theory, in which the individual's objective is not to maximize that function directly, but instead to uphold a commitment to maximize it? Or with guilt-aversion consumer theory, in which the individual feels guilt if she deviates from that commitment? The obvious answer is that these new versions of consumer theory add nothing to the original except unnecessary complexity. Just the same is true when the theory of team reasoning is re-expressed as a commitment to act on team reasoning.

Gui raises more substantial issues when he comments on our treatment of self-sacrifice. Before responding to these comments directly, let us make clear that we do not claim that sociality never involves self-sacrifice. Our central claim is that mutually beneficial exchange can be the content of a genuinely social relationship. We can agree with Nelson that authentic caring is sometimes provided in relationships of dependency (as in her variant of our story of Arthur and Betty). When, at the very end of our paper, we offered the tentative thought that reciprocity might ‘go all the way down’, we did not mean to exclude that kind of caring. We intended only to suggest that the authenticity of relationships, even within families and between friends, should usually be understood in terms of reciprocity rather than sacrifice. Sadly, dependency is sometimes unavoidable, but the responses it requires need not be seen as the paradigm of authentic sociality.

Gui's main concern is not with dependency but with the role of (what he sees as) sacrifice in initiating and maintaining cooperative relationships. He argues that one person's ‘readiness to sacrifice an immediate benefit’ in favour of an actual or potential partner in a joint enterprise can be a ‘powerful message’. Such an action can signal a willingness to initiate a cooperative relationship. Or, by expressing the friendliness and goodwill that characterize fraternal relations, it can help to maintain both parties’ commitments to an ongoing cooperative enterprise. We agree completely, except that we would prefer not to use the language of sacrifice. As Gui makes clear, he is not thinking of a benefactor who intends to transfer wealth to another person. He is thinking of a would-be cooperator who acts with the intention of initiating or maintaining a mutually beneficial relationship, but who incurs the risk that the other person will not reciprocate. This is an attitude of bravery or trust, of casting one's bread on the waters; it may be a virtue, but it is not self-sacrifice. Our original paper includes some discussion of this attitude, in relation to the fair division of the surplus created by cooperation, but we recognize that more work needs to be done here.

Finally, there is the issue of vocabulary raised by Nelson. We have no wish to describe friendliness, goodwill and mutual respect in sexist language. But the word ‘fraternity’ is well-established, with deep roots in the liberal tradition. Etymologically, the reference to brothers is metaphorical. Fraternity is not the relationship of brothers; it is a relationship like that of brothers, and that need not exclude anyone. Some readers may wish to rewrite the Enlightenment trinity as Liberty, Equality, Siblingty; but we prefer the original.