This symposium publishes for the first time three key contributions to the debate on the nature and importance of the distinction between egalitarianism (the view that it is in itself bad, when and because it is unfair, for some to be worse off than others) and prioritarianism (the view that each person's welfare has diminishing marginal moral value and that the moral value of a person's welfare depends only on that person's level of welfare, and not on how anyone else fares). These papers were commissioned by the World Health Organization (WHO) in 2000. They were intended for publication in a WHO volume which has not yet materialized, and this has hindered access to these important papers. Permission was therefore secured from the WHO to publish them here.

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.

Deliberation is the process through which we decide what do to, or what to believe. When we think about what to do, we are engaged in practical deliberation. Theoretical deliberation is when we think about what to believe, or about which judgement to make.

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.

This paper questions the distinction between egalitarianism and prioritarianism, arguing that it is important to separate the reasons for particular social preferences from the contents of these preferences, that it is possible to like equality and separability simultaneously, and that some egalitarians and prioritarians may therefore share the same social preferences (though for different reasons). The case of risky prospects, for which Broome has proposed an interesting example meant to show that egalitarians and prioritarians cannot share the same preferences, is scrutinized. The levelling down objection is also examined.

Group judgements are often – implicitly or explicitly – influenced by their members’ individual expertise. However, given that expertise is seldom recognized fully and that some distortions may occur (bias, correlation, etc.), it is not clear that differential weighting is an epistemically advantageous strategy with respect to straight averaging. Our paper characterizes a wide set of conditions under which differential weighting outperforms straight averaging and embeds the results into the multidisciplinary group decision-making literature.

Both egalitarianism and prioritarianism give value to equality. Prioritarianism has an additively separable value function whereas egalitarianism does not. I show that in some cases prioritarianism and egalitarianism necessarily have different implications: I describe two alternatives G and H such that egalitarianism necessarily implies G is better than H whereas prioritarianism necessarily implies G and H are equally good. I also raise a doubt about the intelligibility of prioritarianism.

The Distribution View provides a model that integrates four distributional concerns in the evaluation of risky prospects. Starting from these concerns, we can generate an ordering over a set of risky prospects, or, starting from an ordering, we can extract a characterization of the underlying distributional concerns. Separability of States and/or Persons for multiple-person risky prospects, for single-person risky prospects and for multiple-person certain prospects are discussed within the model. The Distribution View sheds light on public health policies and provides a framework for the discussion of Parfit's Priority View for risky prospects.

A normative Bayesian theory of deliberation and judgement requires a procedure for merging the evidence of a collection of agents. In order to provide such a procedure, one needs to ask what the evidence is that grounds Bayesian probabilities. After finding fault with several views on the nature of evidence (the views that evidence is knowledge; that evidence is whatever is fully believed; that evidence is observationally set credence; that evidence is information), it is argued that evidence is whatever is rationally taken for granted. This view is shown to have consequences for an account of merging evidence, and it is argued that standard axioms for merging need to be altered somewhat.

I argue that, since the legal order is a public good, an act of legal punishment may be viewed as the imposition of a kind of tax, which I label ‘a quasi-tax’. Once punishment is viewed as a quasi-tax, the traditionally opposed approaches to punishment may be reconciled, as both utility and retribution jointly justify an act of legal punishment. I discuss objections to my argument and I reply to them.

How does an individual decision maker update his or her beliefs in the light of others’ beliefs? We present an empirical investigation that varies decision makers’ access to other peoples’ beliefs: whether they know what course of action others have taken (in this case how a problem is solved) and whether they know why this course of action was taken (why a particular solution is preferred). We propose a number of process models of advice taking that do and do not accommodate the reasons given for belief (epistemic social information), and evaluate which is used through model comparison techniques.

The question for those who are concerned with inequalities is not whether to be an egalitarian or a prioritarian. That choice is mislabelled and misconceived. The relevant question is why distributive inequalities are of more than merely instrumental importance with respect to unrelated goals, such as maximizing well-being. The answer is that lessening inequalities in well-being serves a fundamental commitment to equality of moral status. Depending on the circumstances and what is to be distributed, the underlying concern with equality of moral status (coupled with non-distributional concerns about deprivation) might make one resemble a prioritarian, a non-prioritarian egalitarian, or neither.

We present a model of collective decision making in which aggregation and deliberation are treated simultaneously. Individuals debate in a public forum and potentially revise their judgements in light of deliberation. Once this process is exhausted, a rule is applied to aggregate post-deliberation judgements in order to make a social choice. Restricting attention to three alternatives, we identify conditions under which a democracy is ‘truth-revealing’. This condition says that the deliberation path and the aggregation rule always lead to the correct social choice being made, irrespective of both the original profile of judgements and the size of the electorate.

I address an overlooked question about the structure of the cognitive/conative model of the mind that underlies much of the work in economics, psychology and philosophy: namely, whether conative states are fundamentally monistic (desire-like) or comparative (preference-like). I argue that two seemingly promising sets of theoretical considerations – namely, the structure of Rational Choice Theory, and considerations of computational efficiency – are unable to resolve this debate. Given this, I suggest that a consideration that speaks in favour of the preference-based view is the fact that it makes it easier to explain certain empirically observed patterns in decision making.

I present an analysis of feasibility that generalizes the economic concept of a production possibility frontier and develop a model of the feasibility frontier using the familiar possible worlds technology. I then use the model to show that we cannot reasonably expect that adopting political ideals as long-term reform objectives will guide us toward the realization of morally optimal feasible states of affairs. I conclude by proposing that political philosophers turn their attention to the analysis of actual social failures rather than political ideals.

We propose to strengthen Popper’s notion of falsifiability by adding the requirement that when an observation is inconsistent with a theory, there must be a ‘short proof’ of this inconsistency. We model the concept of a short proof using tools from computational complexity, and provide some examples of economic theories that are falsifiable in the usual sense but not with this additional requirement. We consider several variants of the definition of ‘short proof’ and several assumptions about the difficulty of computation, and study their different implications on the falsifiability of theories.

Assuming that in order to best achieve their goal, individuals adapt their behaviour to the game situation, this paper examines the appropriateness of the Berge behaviour rule and equilibrium as a complement to Nash. We define a Berge equilibrium and explain what it means to play in this fashion. We analyse the rationale of individuals playing in a situational manner, and establish an operational approach that describes the circumstances under which the same individual might play in one fashion versus another.

Robert Sugden has suggested a normative standard of freedom as ‘opportunity’ that is supposed to help realign normative economics – with its traditional rational choice orientation – with behavioural economics. While allowing preferences to be incoherent, he wants to maintain the anti-paternalist stance of orthodox welfare economics. His standard, though, presupposes that people respond to uncertainty about their own future preferences by dismissing any kind of self-constraint. We argue that the approach lacks psychological substance: Sugden's normative benchmark – the ‘responsible person’ – can hardly serve as a convincing role model in a contractarian setting. An alternative concept is introduced, and some implications are briefly discussed.