It has become accepted that social choice is impossible in the absence of interpersonal comparisons of well-being. This view is challenged here. Arrow obtained an impossibility theorem only by making unreasonable demands on social choice functions. With reasonable requirements, one can get very attractive possibilities and derive social preferences on the basis of non-comparable individual preferences. This new approach makes it possible to design optimal second-best institutions inspired by principles of fairness, while traditionally the analysis of optimal second-best institutions was thought to require interpersonal comparisons of well-being. In particular, this approach turns out to be especially suitable for the application of recent philosophical theories of justice formulated in terms of fairness, such as equality of resources.

The principle of belief persistence, or conservativity principle, states that ‘When changing beliefs in response to new evidence, you should continue to believe as many of the old beliefs as possible’ (Harman, 1986, p. 46). In particular, this means that if an individual gets new information, she has to accommodate it in her new belief set (the set of propositions she believes), and, if the new information is not inconsistent with the old belief set, then (1) the individual has to maintain all the beliefs she previously had and (2) the change should be minimal in the sense that every proposition in the new belief set must be deducible from the union of the old belief set and the new information (see, e.g., Gärdenfors, 1988; Stalnaker, 1984). We focus on this minimal notion of belief persistence and characterize it both semantically and syntactically.

Many criticisms have been made of optimization theory (Laville, 1999a). These objections may be explained by the fact that human rationality is bounded – that decisions are constrained by cognitive limitations (Simon, 1982). In the present paper, I will show that if rationality is bounded, then we must study the processes of decision. My thesis is that cognitive limitations lead to procedural rationality. Although this assertion has already been sustained implicitly by Simon (1959) and explicitly by Mongin (1986), it has not been argued in sufficient depth.

What value should we put on our chances of obtaining a good? This paper argues that, contrary to the widely accepted theory of von Neumann and Morgenstern, the value of a chance of some good G may be a non-linear function of the value of G. In particular, chances may have diminishing marginal utility, a property that is termed chance uncertainty aversion. The hypothesis that agents are averse to uncertainy about chances explains a pattern of preferences often observed in the Ellsberg paradox. While these preferences have typically been taken to refute Bayesian decision theory, it is shown that chance risk aversion is perfectly compatible with it.

According to the instrumentalism of Friedman (1970) and Machlup (1967) it is irrelevant whether the explanatory principles or “assumptions” of a theory satisfy any criterion of “plausibility,” “realism,” “credibility,” or “soundness.” In this view the main or only criterion for selecting theories is whether a theory yields empirically testable implications that turn out to be consistent with observations. All we should require or expect from a theory is that it is a useful instrument for the purpose of prediction. Considerations of the “efficiency” of a theory for the purpose of ordering our experiences are permitted (Friedman), but considerations of “plausibility” are not (Friedman and Machlup). “Explanatory assumptions” are not really explanatory in the sense that they claim to represent underlying causal processes in reality; they only serve to generate, by deduction, implications that are in accordance with as many observations as possible.

It is common to define egalitarianism in terms of an inequality ordering, which is supposed to have some weight in overall evaluations of outcomes. Egalitarianism, thus defined, implies that levelling down makes the outcome better in respect of reducing inequality; however, the levelling down objection claims there can be nothing good about levelling down. The priority view, on the other hand, does not have this implication. This paper challenges the common view. The standard definition of egalitarianism implicitly assumes a context. Once this context is made clear, it is easily seen that egalitarianism could be defined alternatively in terms of valuing a benefit to a person inversely to how well off he is relative to others. The levelling down objection does not follow from this definition. Moreover, the common definition does not separate egalitarian orderings from prioritarian ones. It is useful to do this by requiring that on egalitarianism, additively separable orderings should be excluded. But this requirement is stated as a condition on the alternative definition of egalitarianism, from which the levelling down objection does not follow.

This paper develops a Multidimensional Decision Theory and argues that it better captures ordinary intuitions about fair distribution of chances than classical decision theory. The theory is an extension of Richard Jeffrey’s decision theory to counterfactual prospect and is a form of Modal Consequentialism, according to which the value of actual outcomes often depends on what could have been. Unlike existing versions of modal consequentialism, the multidimensional decision theory allows us to explicitly model the desirabilistic dependencies between actual and counterfactual outcomes that, I contend, are at the heart of common intuitions about fair distribution of chances.

Climate ethics have been concerned with polluter pays, beneficiary pays and ability to pay principles, all of which consider climate change as a single negative externality. This paper considers it as a constellation of externalities, positive and negative, with different associated demands of justice. This is important because explicitly considering positive externalities has not to our knowledge been done in the climate ethics literature. Specifically, it is argued that those who enjoy passive gains from climate change owe gains not to the net losers, but to the emitters, just as the emitters owe compensation to the net losers for the negative externality. This is defended by appeal to theoretical virtues and to the social benefits of generating positive externalities, even when those positive externalities are coupled with far greater negative externalities. We call this the Polluter Pays, Then Receives (‘PPTR', or ‘Peter') Principle.

This paper examines the epistemological arguments about markets and planning that emerged in a series of unpublished exchanges between Hayek and Neurath. The exchanges reveal problems for standard accounts of both the socialist calculation debates and logical empiricism. They also raise questions concerning the sources of ignorance and uncertainty in modern economies, and the role of market and non-market organisations in the distribution and coordination of limited knowledge, which remain relevant to contemporary debates in economics. Hayek had argued that Neurath's work exemplified the errors of rationalism that underpinned the socialist project. In response Neurath highlighted assumptions about the limits of reason and predictability that the two theorists shared and attempted to turn those assumptions back against Hayek in a defence of the possibility of socialist planning. The paper critically compares Neurath's and Hayek's criticisms of rationalism and considers how far Neurath is successful in his attempt to employ Hayek's assumptions against Hayek himself.

How should we define the feasible set? Even when individuals agree on facts and values, as traditionally construed, different views on feasibility may suffice to produce very different policy conclusions. Focusing on the difficulties in the feasibility concept may help us resolve some policy disagreements, or at least identify the sources of those disagreements. Feasibility is most plausibly a matter of degree rather than of kind. Normative economic reasoning therefore faces a fuzzy social budget constraint. Iterative reasoning about feasibility and desirability may help us overcome these problems.

Paradoxical results concerning judgment aggregation have recently been invoked to defend the thesis that a corporate agent can be morally responsible for a decision without any of its individual members bearing such responsibility. I contend that the arguments offered for this irreducibility thesis are inconclusive. They do not pay enough attention to how we evaluate individual moral responsibility, in particular not to the role that a flawed assessment of the normative reasons that bear on the issue to be decided on play in this context. I go on to propose a method for distributing corporate responsibility to individual members within the judgment aggregation framework.

It has been argued by several philosophers that a morally motivated rational agent who has to make decisions under conditions of moral uncertainty ought to maximize expected moral value in his choices, where the expectation is calculated relative to the agent's moral uncertainty. I present a counter-example to this thesis and to a larger family of decision rules for choice under conditions of moral uncertainty. Based on this counter-example, I argue against the thesis and suggest a reason for its failure – that it is based on the false assumption that inter-theoretical comparisons of moral value are meaningful.

In a recent examination of the origins of ordinal utility theory in neoclassical economics, Robert D. Cooter and Peter Rappoport argue that the ordinalist revolution of the 1930s, after which most economists abandoned interpersonal utility comparisons as normative and unscientific, constituted neither unambiguous progress in economic science nor the abandonment of normative theorizing, as many economists and historians of economic thought have generally believed (Cooter and Rappoport, 1984). Rather, the widespread acceptance of ordinalism, with its focus on Pareto optimality, simply represented the emergence of a new neoclassical research agenda that, on the one hand, defined economics differently than had the material welfare theorists of the cardinal utility school and, on the other, adopted a positivist methodology in contrast to the less restrictive empiricism of the cardinalists.

It is a particular pleasure to be able to participate in this symposium in honor of Amartya Sen. We agree on a wide range of topics, but I will focus here on an area of relative disagreement. Sen is much more attracted to consequentialism than I am, and the main topic of my paper will be the particular version of consequentialism that he has articulated and the reasons why he is drawn to this view.

As an emerging discipline, neuroeconomics faces considerable methodological and practical challenges. In this paper, I suggest that these challenges can be understood by exploring the similarities and dissimilarities between the emergence of neuroeconomics and the emergence of cognitive and computational neuroscience two decades ago. From these parallels, I suggest the major challenge facing theory formation in the neural and behavioural sciences is that of being under-constrained by data, making a detailed understanding of physical implementation necessary for theory construction in neuroeconomics. Rather than following a top-down strategy, neuroeconomists should be pragmatic in the use of available data from animal models, information regarding neural pathways and projections, computational models of neural function, functional imaging and behavioural data. By providing convergent evidence across multiple levels of organization, neuroeconomics will have its most promising prospects of success.

Revealed preference approaches to modelling agents’ choices face two seemingly devastating explanatory objections. The no self-explanation objection imputes a problematic explanatory circularity to revealed preference approaches, while the causal explanation objection argues that, all things equal, a scientific theory should provide causal explanations, but revealed preference approaches decidedly do not. Both objections assume a view of explanation, the constraint-based view, that the revealed preference theorist ought to reject. Instead, the revealed preference theorist should adopt a unificationist account of explanation, allowing her to escape the two explanatory problems discussed in this paper.

This paper builds upon, but substantially revises, John Harsanyi's concept of ‘extended preferences’. An individual ‘history’ is a possible life that some person (a subject) might lead. Harsanyi supposes that a given spectator, formulating her ethical preferences, can rank histories by empathetic projection: putting herself ‘in the shoes’ of various subjects. Harsanyi then suggests that interpersonal comparisons be derived from the utility function representing spectators’ (supposedly common) ranking of history lotteries. Unfortunately, Harsanyi's proposal has various flaws, including some that have hitherto escaped scholarly attention. In particular, it ignores the limits of personal identity. If the subject has welfare-relevant attributes that the spectator cannot acquire without changing who she is, full empathetic identification of the latter with the former becomes impossible. This paper proposes instead to use sympathy as the attitude on a spectator's part that allows us to make sense of her extended preferences. Sympathy – an attitude of care and concern – is a psychological state quite different from empathy. We should also allow for hetereogeneity in spectators’ extended preferences. Interpersonal comparisons emerge from a plurality of sympathetic spectators, not (as per Harsanyi) from a common empathetic ranking.

It often appears that the most appropriate form of addressing disadvantage related to disability is through policies that can be called “status enhancements”: changes to the social, cultural and material environment so that the difficulties experienced by those with impairments are reduced, even eradicated. However, status enhancements can also have their limitations. This paper compares the relative merits of policies of status enhancement and “personal enhancement”: changes to the disabled person. It then takes up the question of how to assess the priority of the claims of disabled people in the face of scarcity of resources for which there can be many competing social claims, arguing for the theory of “declustering disadvantage”.

Proponents of evidence-based policy (EBP) call for public policy to be informed by high-quality evidence from randomized controlled trials. This methodological preference aims to promote several epistemic values, e.g. rigour, unbiasedness, precision, and the ability to obtain causal conclusions. I argue that there is a trade-off between these epistemic values and several non-epistemic, moral and political values. This is because the evidence afforded by standard EBP methods is differentially useful for pursuing different moral and political values. I expand on how this challenges ideals of value-freedom and -neutrality in EBP, and offer suggestions for how EBP methodology might be revised.