Margaret Gilbert

This article explores the question: what is it for two or more people to intend to do something in the future? In a technical phrase, what is it for people to share an intention ? Extending and refining earlier work of the author’s, it argues for three criteria of adequacy for an account of shared intention (the disjunction, concurrence, and obligation criteria) and offers an account that satisfies them. According to this account, in technical terms explained in the paper, people share an intention when and only when they are jointly committed to intend as a body to do such-and-such in the future. This account is compared and contrasted with the common approach that treats shared intention as a matter of personal intentions, with particular reference to the work of Michael Bratman.

Margaret Gilbert offers an incisive new approach to a classic problem of political philosophy: when and why should I do what the law tells me to do? Do I have special obligations to conform to the laws of my own country and if so, why? In what sense, if any, must I fight in wars in which my country is engaged, if ordered to do so, or suffer the penalty for law-breaking the law imposes - including the death penalty? Gilbert's accessible book offers a provocative and compelling case in favour of citizens' obligations to the state, while examining how these can be squared with self-interest and other competing considerations.

Philosophers using game-theoretical models of human interactions have, I argue, often overestimated what sheer rationality can achieve. (References are made to David Gauthier, David Lewis, and others.) In particular I argue that in coordination problems rational agents will not necessarily reach a unique outcome that is most preferred by all, nor a unique 'coordination equilibrium' (Lewis), nor a unique Nash equilibrium. Nor are things helped by the addition of a successful precedent, or by common knowledge of generally accepted personal principles. Commitments like those generated by agreements may be necessary for rational expectations to arise. Social conventions, construed as group principles (following the analysis in my book On Social Facts), would suffice for this task.

What is it for a group to believe something? A summative account assumes that for a group to believe that p most members of the group must believe that p. Accounts of this type are commonly proposed in interpretation of everyday ascriptions of beliefs to groups. I argue that a nonsummative account corresponds better to our unexamined understanding of such ascriptions. In particular I propose what I refer to as the joint acceptance model of group belief. I argue that group beliefs according to the joint acceptance model are important phenomena whose aetiology and development require investigation. There is an analogous phenomenon of social or group preference, which social choice theory tends to ignore.