Logical puzzles like the doctrinal paradox raise the problem of how to aggregate individual judgements into a collective judgement, or alternatively, how to merge collectively inconsistent knowledge bases. In this paper, we view judgement aggregation as a function on propositional logic valuations, and we investigate how logic constrains judgement aggregation. In particular, we show that there is no non-dictatorial decision method for aggregating sets of judgements in a logically consistent way if the decision method is local, i.e., only depends on (...) the individual judgements on the proposition under consideration. (shrink)

The primary aim of this paper is to analyze the concept of degrees of causal contribution for actual events and examine the way in which it can be formally defined. This should go some way to filling out a gap in the legal and philosophical literature on causation. By adopting the conception of a cause as a necessary element of a sufficient set (the so-called NESS test) we show that the concept of degrees of causation can be given clear and (...) even empirical meaning. We then apply a game theoretical framework to derive a measure of causal contribution. Our favoured measure turns out to be a generalised version of the normalized Penrose–Banzhaf index of voting power. (shrink)

This paper examines the structure of moral responsibility for outcomes. A central feature of the analysis is a condition that we term the 'avoidance potential', which gives precision to the idea that moral responsibility implies a reasonable demand that an agent should have acted otherwise. We show how our theory can allocate moral responsibility to individuals in complex collective action problems, an issue that sometimes goes by the name of 'the problem of many hands'. We also show how it allocates (...) moral responsibility in the classic Frankfurt example. (shrink)

We present evidence for the existence of `responsibility voids' in committee decision-making, that is, the existence of situations where no member of a committee can individually be held morally responsible for the outcome. We analyse three types of reasons (causal, normative and epistemic) for the emergence of responsibility voids, and show that each of them can occur in committees. But the conditions for these voids are so restrictive as to reduce the philosophical or institutional significance they might be thought to (...) possess. (shrink)

The condition of liberty which Sen used in his famous theorem on the impossibility of the Paretian liberal was defined in terms of individual preferences. The preference-based approach has been the subject of much criticism, which led to the evolution of the game-theoretic analysis of rights. In this approach no references to individual preferences are made. Two questions are examined in this paper: how can different types of right be distinguished within a game-theoretic setting, and how do rights come into (...) existence? These questions are addressed on the basis of ideas originating from legal theory The discussion shows that an analysis of rights should take account of the whole legal system of which a legal norm forms part. Furthermore, it reveals that preferences should be re-introduced into the formal study of individual rights. (shrink)