In this book, T. M. Scanlon offers new answers to these questions, as they apply to the central part of morality that concerns what we owe to each other.

In this paper, I explain a challenge to the Equal Weight View coming from the psychology of group inquiry, and evaluate its merits. I argue that while the evidence from the psychology of group inquiry does not give us a reason to reject the Equal Weight View, it does require making some clarifications regarding what the view does and does not entail, as well as a revisiting the ethics of belief.

How should one react when one has a belief, but knows that other people—who have roughly the same evidence as one has, and seem roughly as likely to react to it correctly—disagree? This paper argues that the disagreement of other competent inquirers often requires one to be much less confident in one’s opinions than one would otherwise be.

I propose a dynamical analysis of interaction in anarchy, and argue that this kind of dynamical analysis is a more promising route to predicting the outcome of anarchy than the more traditional a priori analyses of anarchy in the literature. I criticize previous a priori analyses of anarchy on the grounds that these analyses assume that the individuals in anarchy share a unique set of preferences over the possible outcomes of war, peace, exploiting others and suffering exploitation. Following Hobbes' classic (...) analysis of anarchy, I maintain that typically in anarchy some moderate individuals will most desire mutual cooperation while other dominators will most desire to exploit others' cooperation. I argue that once one allows for different types of individuals in anarchy, any a priori analysis of anarchy requires unrealistic assumptions regarding the agents' common knowledge of their situation. However, this move also suggests a dynamical analysis of anarchy, one that assumes no common knowledge. In the Variable Anticipation threshold model developed here, individuals modify their behavior as they learn from repeated interactions. I present specific instances of this model where the individuals in anarchy converge to different equilibria corresponding to either peace or war, depending on the initial conditions. I show that individuals are liable to converge to Hobbes' war of all against all even if only a small percentage of are dominators. The presence of only a few “nasty” individuals gradually drives all, including those inclined to be “nicer”, to imitate the “nasty” conduct of these few. This dynamic analysis suggests that the Hobbesian war in anarchy is indeed inevitable in most realistic circumstances. You have the same propension, that I have, in favor of what is contiguous above what is remote. You are, therefore, naturally carry'd to commit acts of injustice as well as I. Your example both pushes me forward in this way by imitation, and also affords me a new reason for any breach of equity, by showing me, that I shou'd be the cully of my integrity, if I alone shou'd impose on myself a severe restraint amidst the licentiousness of others. (David Hume, A Treatise of Human Nature) (Published Online July 11 2006) Footnotes1 Thanks to Luc Bovens, Sharon Lloyd, Brian Skyrms, Susanne Sreedhar and an anonymous referee for many helpful comments of early versions of this essay. (shrink)

Public reason theories are characterized by three conditions: constructivism, representation, and stability. Constructivism holds that justification does not rely on any antecedent moral or political values outside of the procedure of agreement. Representation holds that the reasons for the choice in the model must be rationally explicable to real agents outside the model. Stability holds that the principles chosen in the procedure should be stable upon reflection, especially in the face of diversity in a pluralistic society. Choice procedures that involve (...) at least two-stages with different information, as Rawls’s theory does, will be path-dependent and not meet the condition of representation since it will not be globally coherent. Attempts to solve this problem without eliminating the segmentation of choice in the procedure will run afoul of constructivism or stability. This problem is instructive because it highlights how public reason theories must evolve in the face of increased concerns about diversity. (shrink)

This article provides a critical introduction to contractualism as a moral or ethical theory, that is, as a theory of the rightness and wrongness of individual conduct – focusing specifically on the influential 'Kantian' version of contractualism due to T. M. Scanlon. I begin by elucidating the key features of Scanlon's contractualism: justifiability to others; reasonable rejectability; the individualist restriction; and mutual recognition. I then turn to discuss both its appeal and the main objections that have been raised to it (...) – objections concerning our duties to the cognitively limited and impaired, aggregation, demandingness, normativity and explanatory adequacy. I conclude by mentioning some contractualist alternatives to Scanlon's theory. (shrink)

In this paper we argue that there is a kind of moral disagreement that survives the Rawlsian veil of ignorance. While a veil of ignorance eliminates sources of disagreement stemming from self-interest, it does not do anything to eliminate deeper sources of disagreement. These disagreements not only persist, but transform their structure once behind the veil of ignorance. We consider formal frameworks for exploring these differences in structure between interested and disinterested disagreement, and argue that consensus models offer us a (...) solution concept for disagreements behind the veil of ignorance. (shrink)

It is argued that the Nash bargaining solution cannot serve as a principle of distributive justice because (i) it cannot secure stable cooperation in repeated interactions and (ii) it cannot capture our moral intuitions concerning distributive questions. In this article, I propose a solution to the first problem by amending the Nash bargaining solution so that it can maintain stable cooperation among rational bargainers. I call the resulting principle the stabilized Nash bargaining solution. The principle defends justice in the form (...) 'each according to her basic needs and above this level according to her relative bargaining power'. In response to the second problem, I argue that the stabilized Nash bargaining solution can serve as a principle of distributive justice in certain situations where moral reasoning is reduced to instrumental reasoning. In particular, I argue that rational individuals would choose the stabilized Nash bargaining solution in Rawls' original position. (shrink)

Game theory poses problems for modeling rational belief, but it does not need a new theory of rationality. Experimental results that suggest otherwise often reveal difficulties in testing game theory, rather than mistakes or paradoxes. Even though the puzzles Colman discusses show no inadequacy in the standard theory of rationality, they show that improved models of belief are needed.

How should you take into account the opinions of an advisor? When you completely defer to the advisor's judgment, then you should treat the advisor as a guru. Roughly, that means you should believe what you expect she would believe, if supplied with your extra evidence. When the advisor is your own future self, the resulting principle amounts to a version of the Reflection Principle---a version amended to handle cases of information loss. When you count an advisor as an epistemic (...) peer, you should give her conclusions the same weight as your own. Denying that view---call it the ``equal weight view''---leads to absurdity: the absurdity that you could reasonably come to believe yourself to be an epistemic superior to an advisor simply by noting cases of disagreement with her, and taking it that she made most of the mistakes. Accepting the view seems to lead to another absurdity: that one should suspend judgment about everything that one's smart and well-informed friends disagree on, which means suspending judgment about almost everything interesting. But despite appearances, the equal weight view does not have this absurd consequence. Furthermore, the view can be generalized to handle cases involving not just epistemic peers, but also epistemic superiors and inferiors. (shrink)

One of John Rawls’s major aims, when he wrote A Theory of Justice, was to present a superior alternative to utilitarianism. Rawls’s worry was that utilitarianism may fail to protect the fundamental rights and liberties of persons in its attempt to maximize total social welfare. Rawls’s main argument against utilitarianism was that, for such reasons, the representative parties in the original position will not choose utilitarianism, but will rather choose his justice as fairness, which he believed would securely protect the (...) worth of everybody’s basic rights and liberties. In this paper, I will argue that, under close formal examination, Rawls’s argument against utilitarianism is self-defeating. That is, I will argue that Rawls’s own reasons, assumptions, and the many theoretical devices he employs demonstrably imply that the representative parties in the original position will choose utilitarianism instead of justice as fairness. (shrink)

Hobbes’s own justification for the existence of governments relies on the assumption that, without a government, our lives in the state of nature would result in a state of war of every man against every man. Many contemporary scholars have tried to explain why universal war is unavoidable in Hobbes’s state of nature by utilizing modern game theory. However, most game-theoretic models that have been presented so far do not accurately capture what Hobbes deems to be the primary cause of (...) conflict in the state of nature – which is uncertainty, rather than people’s egoistic psychology. Any game- theoretic model that does not incorporate uncertainty into the picture is, therefore, I claim, the wrong model. In this paper, I use Bayesian game-theory to show how universal conflict can break-out in the state of nature - even when the majority of the population would strictly prefer to cooperate and seek peace with other people - due to uncertainty about the other person’s type. Along the way, I show that the valuation of one’s own life is one of the central mechanisms that drives Hobbes’s pessimistic conclusion. (shrink)

Some philosophers believe that when epistemic peers disagree, each has an obligation to accord the other's assessment the same weight as her own. I first make the antecedent of this Equal-Weight View more precise, and then I motivate the View by describing cases in which it gives the intuitively correct verdict. Next I introduce some apparent counterexamples – cases of apparent peer disagreement in which, intuitively, one should not give equal weight to the other party's assessment. To defuse these apparent (...) counterexamples, an advocate of the View might try to explain how they are not genuine cases of peer disagreement. I examine David Christensen's and Adam Elga's explanations and find them wanting. I then offer a novel explanation, which turns on a distinction between knowledge from reports and knowledge from direct acquaintance. Finally, I extend my explanation to provide a handy and satisfying response to the charge of self-defeat. (shrink)

This article is extracted from a forthcoming book, ‘Natural Justice’. It is a nontechnical introduction to the part of game theory immediately relevant to social contract theory. The latter part of the article reviews how concepts such as trust, responsibility, and authority can be seen as emergent phenomena in models that take formal account only of equilibria in indefinitely repeated games. Key Words: game theory • equilibrium • evolutionary stability • reciprocity • folk theorem • trust • altruism • responsibility (...) • authority. (shrink)

This article examines the central epistemological issues tied to the recognition of disagreement.