We give two social aggregation theorems under conditions of risk, one for constant population cases, the other an extension to variable populations. Intra and interpersonal welfare comparisons are encoded in a single ‘individual preorder’. The theorems give axioms that uniquely determine a social preorder in terms of this individual preorder. The social preorders described by these theorems have features that may be considered characteristic of Harsanyi-style utilitarianism, such as indifference to ex ante and ex post equality. However, the theorems are (...) also consistent with the rejection of all of the expected utility axioms, completeness, continuity, and independence, at both the individual and social levels. In that sense, expected utility is inessential to Harsanyi-style utilitarianism. In fact, the variable population theorem imposes only a mild constraint on the individual preorder, while the constant population theorem imposes no constraint at all. We then derive further results under the assumption of our basic axioms. First, the individual preorder satisfies the main expected utility axiom of strong independence if and only if the social preorder has a vector-valued expected total utility representation, covering Harsanyi’s utilitarian theorem as a special case. Second, stronger utilitarian-friendly assumptions, like Pareto or strong separability, are essentially equivalent to strong independence. Third, if the individual preorder satisfies a ‘local expected utility’ condition popular in non-expected utility theory, then the social preorder has a ‘local expected total utility’ representation. Fourth, a wide range of non-expected utility theories nevertheless lead to social preorders of outcomes that have been seen as canonically egalitarian, such as rank-dependent social preorders. Although our aggregation theorems are stated under conditions of risk, they are valid in more general frameworks for representing uncertainty or ambiguity. (shrink)

Since the last ice age, when ice enveloped most of the northern continents, the earth has warmed by about five degrees. Within a century, it is likely to warm by another four or five. This revolution in our climate will have immense and mostly harmful effects on the lives of people not yet born. We are inflicting this harm on our descendants by dumping greenhouse gases into the atmosphere. We can mitigate the harm a little by taking measures to control (...) our emissions of these gases, and to adapt to the changes by, for instance, building sea walls around coastlines threatened by rising sea levels. But these measures will be very expensive, and the costs will be born by us, the present generation, whereas the benefits will come to future generations. How much should we sacrifice for the sake of the future? Economists and philosophers have independently worked on the question of our responsibility to future generations. This book brings their work together and applies it to global warming. It suggests a programme for future research on the economic and ethical issues. The book is intended for economists, and for philosophers and other social scientists who have a little knowledge of economic methods. (shrink)

Values are incommensurable when they cannot be measured on a single cardinal scale. Many philosophers suggest that incommensurability can help us solve the problems of population ethics. I agree. But some philosophers claim that populations bear incommensurable values merely because they contain different numbers of people, perhaps within some range. I argue that mere differences in how many people exist, even within some range, do not suffice for incommensurability. I argue that the intuitive neutrality of creating happy people is better (...) captured by a version of average utilitarianism. But this view is problematic. So I suggest a version of total utilitarianism that avoids the repugnant conclusion by appealing to incommensurable dimensions of wellbeing. (shrink)

Ethical theory faces a group of difficult puzzles concerning populations. Here is one: would it be right to maximize utility by causing the number of people existing in the further future to be very, very large, even if this means that each of their lives is barely worth living? Derek Parfit concludes that standard utilitarianism yields the result that it would be right to create such a world. He calls this conclusion "repugnant." I begin with an examination of the objection, (...) in which I argue that the problem is axiological, not normative. I present my interpretation of the problem, and consider and reject the most popular and plausible responses in the literature. ;Many people agree with Parfit that the repugnant conclusion is unacceptable. They see this as a strong objection to impersonalism, and conclude that only person-affecting utilitarianism solves the population problems in question. I argue that the most credible person-affecting theories incorrectly answer simple population questions and are deficient in other respects. ;Need we accept Parfit's objection? I advance my own view---that there are totalistic axiologies that do not imply the repugnant conclusion, and defeat the mere addition paradox. I show that these theories have much in common with classical totalism, and they give the intuitively correct result in the crucial cases under consideration. (shrink)

While different worries about population size are present in public debates, political philosophers often take population size as given. This paper is an attempt to formulate a Rawlsian liberal egalitarian approach to population size: does it make sense to speak of ‘too few’ or ‘too many’ people from the point of view of justice? It argues that, drawing on key features of liberal egalitarian theory, several clear constraints on demographic developments – to the extent that they are under our control (...) – can be formulated. Based on these claims, we can clarify both the grounds and content of our obligations to future generations. (shrink)