When Mr. Collins proposes to Elizabeth Bennet early on in Jane Austen's Pride and Prejudice, he begins by saying " before I am run away with by my feelings on this subject, perhaps it will be advisable for me to state my reasons for marrying," and then goes on to list them. When Elizabeth rejects him, he fails to take her rejection seriously, putting it down to her wish "of increasing my love by suspense, according to the usual practice of elegant females." Moreover, he backs up this conclusion by pointing out that since she has no reasons that he can see to reject him, her refusal is "merely words." At this point, Elizabeth rejects him more forcefully (though not successfully) and asks that he consider her not as "an elegant female intending to plague you, but as a rational creature speaking the truth from her heart." Attention to this exchange brings to light a certain ambiguity in how we think and talk about reasoning. Both Mr. Collins and Elizabeth expect their encounter to be an instance of reasoning, and both criticize the other for failing to live up to that expectation. It turns out, however, that they have very different activities in mind. For Mr. Collins, reasoning is a matter of aligning one's thoughts, words and actions with a set of established principles: logical and rational, but also prudential, social and moral. Failure to reason comes from ignoring these principles, or giving sway to one's emotions or passions. In such instances, one ends up uttering mere words, and not giving reasons. According to this view, he is reasoning and Elizabeth is not. For Elizabeth, however, reasoning requires that a person be responsive to those with whom he is reasoning. It calls for genuine listening and exchange. Failure to reason in this sense comes in the form of commanding or deferring to, or, in Mr. Collins's case, merely ignoring what our interlocutor says. On this view, it is Mr. Collins, list of reasons and all, who is failing to reason. Le déjeuner (The Lunch) by Pierre-Auguste Renoir (Oil on canvas, 90x80 cm, 1879. The Barnes Foundation, Merion, USA) A great deal of theoretical work on reasoning, whether in philosophy, economics, psychology or the other social sciences, takes up Mr. Collins's picture of what reasoning involves, and a great deal of our ordinary understanding of the place of reasoning in human life is also guided by this picture. So, for instance, we analyze and describe instances of reasoning together by asking whether their participants conform to norms and principles of reason. We then picture reasoning together as an exercise in bargaining or negotiation towards an agreement or decision, or a way of pooling resources to improve our ability to reach rational conclusions. What gets lost in such accounts, however, is precisely the values realized by reasoning of the sort Elizabeth demands: the values intrinsic to certain forms of human living together. In addition, reliance on this picture often leads us to dismiss too quickly those with whom we disagree and whom we don't fully understand as not fully rational or reasonable, as uttering "mere words." In order, then, to think clearly about the activity of reasoning that involves genuinely speaking and thinking and acting together, the sort of reasoning that Elizabeth hopes for in a marriage as well as a proposal, we need, I argue, to build an account of this activity from the ground up. Doing so offers us what I call a social picture of reasoning. Such a picture enables us to think differently about the possibilities of living together because it offers us new tools for describing this activity and criticizing its failures. It gives us, for instance, the background framework to make good on Elizabeth's charge that it is Mr. Collins and not she who is guilty of a failure of reasoning, despite his repeated urging of otherwise unimpeachable reasons. The social picture of reasoning describes reasoning as an activity that is interactive, responsive and reciprocal. It proposes that we think of reasoning as involving the ongoing activity of inviting one another to take our words as speaking for them as well. That is to say that in reasoning together, each of us makes open-ended proposals to the other to see the world a certain way, to take norms or ideas or conceptualizations as potential common ground. By describing reasoning in terms of the issuing of invitations, I highlight that for what we say to one another to count as reasoning, we have to leave it always open to criticism and rejection. One consequence of this central feature of reasoning is that reasoning does not involve wielding the sort of authority that we commonly associate with reason. Thus, reasoning with someone is not an alternative way of compelling her to bend to the force of the better argument, but a joint exploration of whether those reasoning can stand together on the ground proposed. It requires not so much the deployment of strings of complex argumentation or the marshaling of irrefutable facts and principles, but the articulation of where one stands, and the ability and willingness to hear and respond to what others say about where one stands. It requires that each participant in the joint activity of reasoning is as open to her interlocutors' influence on her as she hopes they will be to her influence on them. Reasoning, as the social picture I develop in this book conceives it, is an on-going, rather than an end-directed, activity. Consequently, in order to understand the activity of reasoning, we cannot look to its ends, as more traditional accounts do. Rather, I argue that we should think of reasoning as a species of casual conversation, sharing the norms that characterize conversation, and yet requiring greater levels of responsiveness and reciprocity than is needed merely to converse. We can then distinguish types of reasoning by the tightness of the requirements of responsiveness. What, then, defines an utterance as a reason is that it takes place within a form of reasoning, which is to say within a form of activity characterized by a set of norms, although not the sort of rational principles on which Mr. Collins relies. The book elucidates a set of norms that characterize reasoning: norms governing the intelligibility of what we say, and the relationships we stand in to those with whom we reason and to what we say. In particular, engaging in the activity of reasoning I depict requires that what people say to each other is intelligible as an invitation, and is left open to their rejection or criticism of it. It also requires that they stand in reciprocal relations in which each accepts that she can be touched or moved by what others say as she hopes to touch or move them with what she says. Finally, it requires that each offers her invitations in good faith. Looking at reasoning as the social picture reveals it to us opens up a new field of reflection and study. By characterizing reasoning in terms of levels of responsiveness, we can offer new characterizations of the norms of deliberation that make them significantly different from those governing bargaining. Because reasoning involves always leaving what one says open to rejection and criticism, it also turns out that determining whether people are reasoning together requires looking forward to how they go on rather than merely back at what has been said. That opens the possibility that we might bring others to reason with us not by force or command but by reasoning with them. Such perspectives and others that emerge in the development of the social picture provide valuable payoffs and possibilities for action and interaction, both political and personal. They offer a path forward for democratic civic engagement as well as a better understanding of how to propose to a rational creature.