In this study I analyse the performance of a democratic decision-making rule: the weighted majority rule. It assigns to each voter a number of votes that is proportional to her stakes in the decision. It has been shown that, for collective decisions with two options, the weighted majority rule in combination with self-interested voters maximises the common good when the latter is understood in terms of either the sum-total or prioritarian sum of the voters’ well-being. The main result of my (...) study is that this argument for the weighted majority rule — that it maximises the common good — can be improved along the following three main lines. (1) The argument can be adapted to other criteria of the common good, such as sufficientarian, maximin, leximin or non-welfarist criteria. I propose a generic argument for the collective optimality of the weighted majority rule that works for all of these criteria. (2) The assumption of self-interested voters can be relaxed. First, common-interest voters can be accommodated. Second, even if voters are less than fully competent in judging their self-interest or the common interest, the weighted majority rule is weakly collectively optimal, that is, it almost certainly maximises the common good given large numbers of voters. Third, even for smaller groups of voters, the weighted majority rule still has some attractive features. (3) The scope of the argument can be extended to decisions with more than two options. I state the conditions under which the weighted majority rule maximises the common good even in multi-option contexts. I also analyse the possibility and the detrimental effects of strategic voting. Furthermore, I argue that self-interested voters have reason to accept the weighted majority rule. (shrink)

This paper considers the relation between philosophical discussions of, and social-scientific research into popular beliefs about, distributive justice. The first part sets out the differences and tensions between the two perspectives, identifying considerations which tend to lead adherents of each discipline to regard the other as irrelevant to its concerns. The second discusses four reasons why social scientists might benefit from philosophy: problems in identifying inconsistency, the fact that non-justice considerations might underlie distributive judgments, the way in which different principles (...) of justice can yield the same concrete distributive judgments, and the ambiguity of key terms. The third part distinguishes and evaluates three versions of the claim that normative theorising about justice can profit from empirical research into public opinion: that its findings are food for thought, that they amount to feasibility constraints, and that they are constitutive of normatively justified principles of justice. The view that popular opinion about justice has a strongly constitutive role to play in justifying principles of distributive justice stricto sensu is rejected, but it is argued that what the people think (and what they can reasonably be expected to come to think) on distributive matters can be an important factor for the political theorist to take into account, for reasons of legitimacy, or feasibility, or both. (shrink)