Is the overall value of a world just the sum of values contributed by each value-bearing entity in that world? Additively separable axiologies (like total utilitarianism, prioritarianism, and critical level views) say 'yes', but non-additive axiologies (like average utilitarianism, rank-discounted utilitarianism, and variable value views) say 'no'. This distinction is practically important: additive axiologies support 'arguments from astronomical scale' which suggest (among other things) that it is overwhelmingly important for humanity to avoid premature extinction and ensure the existence of a (...) large future population, while non-additive axiologies need not. We show, however, that when there is a large enough 'background population' unaffected by our choices, a wide range of non-additive axiologies converge in their implications with some additive axiology -- for instance, average utilitarianism converges to critical-level utilitarianism and various egalitarian theories converge to prioritiarianism. We further argue that real-world background populations may be large enough to make these limit results practically significant. This means that arguments from astronomical scale, and other arguments in practical ethics that seem to presuppose additive separability, may be truth-preserving in practice whether or not we accept additive separability as a basic axiological principle. (shrink)

Recently, in his Rolf Schock Prize Lecture, Derek Parfit has suggested a novel way of avoiding the Repugnant Conclusion by introducing what he calls “imprecision” in value comparisons. He suggests that in a range of important cases, populations of different sizes are only imprecisely comparable. Parfit suggests that this feature of value comparisons opens up a way of avoiding the Repugnant Conclusion without implying other counterintuitive conclusions, and thus solves one of the major challenges in ethics. In this article, I (...) try to clarify Parfit's proposal and evaluate whether it will help us with the paradoxes in population ethics. (shrink)

In Derek Parfit's original formulation the Repugnant Conclusion is characterized as follows: “For any possible population of at least ten billion people, all with a very high quality of life, there must be some much larger imaginable population whose existence, if other things are equal, would be better even though its members have lives that are barely worth living” (Parfit 1984). The Repugnant Conclusion highlights a problem in an area of ethics which has become known as population ethics . The (...) last three decades have witnessed an increasing philosophical interest in questions such as “Is it possible to make the world a better place by creating additional happy creatures?” and “Is there a moral obligation to have children?” The main problem has been to find an adequate theory about the moral value of states of affairs where the number of people, the quality of their lives, and their identities may vary. Since, arguably, any reasonable moral theory has to take these aspects of possible states of affairs into account when determining the normative status of actions, the study of population ethics is of general import for moral theory. As the name indicates, Parfit finds the Repugnant Conclusion unacceptable and many philosophers agree. However, it has been surprisingly difficult to find a theory that avoids the Repugnant Conclusion without implying other equally counterintuitive conclusions. Thus, the question as to how the Repugnant Conclusion should be dealt with and, more generally, what it shows about the nature of ethics has turned the conclusion into one of the cardinal challenges of modern ethics. (shrink)

This thesis consists of a series of papers in population ethics: a subfield of normative ethics concerned with the distinctive issues that arise in cases where our actions can affect the identities or number of people of who ever exist. Each paper can be read independently of the others. In Chapter 1, I present a dilemma for Archimedean views in population axiology: roughly, those views on which adding enough good lives to a population can make that population better than any (...) other. In Chapter 2, I extend Gustaf Arrhenius’s famous impossibility theorems in population axiology into the domain of choices under risk. My risky impossibility theorems dispense with the assumption that welfare levels are finitely fine-grained, and so tell against lexical views in population axiology. In Chapter 3, I present objections to critical-level and critical-range views in population axiology. I then sketch out what I call the ‘Imprecise Exchange Rates View’ and argue that it is an attractive alternative. In Chapter 4, I address critical-level and critical-range views again. This time, I note that they are vulnerable to objections from biographical identity: identity between lives. I suggest that these objections give us reason to reject critical-level and critical-range views and embrace the Total View. In Chapter 5, I argue that objections of the same form – objections from personal identity – tell against person-affecting views in population ethics. In Chapter 6, I draw out some counterintuitive implications of two recent complaints-based theories of the procreation asymmetry. (shrink)

In Chapter 17 of his magnificent Reasons and Persons, Derek Parfit asks what he describes as an ‘awesome question’: ‘How many people should there ever be?’ For a utilitarian like me, the answer seems simple: there should be however many people it takes to make the world best. Unfortunately, if I answer Parfit's awesome question in this way, I may sink myself in a quagmire of axiological confusion. In this paper, I first describe certain aspects of the quagmire. Then I (...) introduce and explain some of the elements of a novel axiological view – ‘justicism’. Justicism is derived from some ideas originally suggested by Franz Brentano. It was developed in an effort to solve certain other problems confronting utilitarianism – problems explicitly about justice. I think, however, that as a sort of happy by-product, justicism also generates a plausible answer to Parfit's awesome question. This may come as a bit of surprise, since justicism is a form of totalism, and it is widely thought that no totalistic theory can provide a satisfactory answer to Parfit's question. After presenting and explaining my proposed solution, I address some objections. (shrink)

A principal aim of the branch of ethics called ‘population theory’ or ‘population ethics’ is to find a plausible welfarist axiology, capable of comparing total outcomes with respect to value. This has proved an exceedingly difficult task. In this paper I shall state and discuss two ‘trilemmas’, or choices between three unappealing alternatives, which the population ethicist must face. The first trilemma is not new. It originates with Derek Parfit's well-known ‘Mere Addition Paradox’, and was first explicitly stated by Yew-Kwang (...) Ng. I shall argue that one horn of this trilemma is less unattractive than Parfit and others have claimed. The second trilemma, which is a kind of mirror image of the first, appears hitherto to have gone unnoticed. Apart from attempting to resolve the two trilemmas, I shall suggest certain features which I believe a plausible welfarist axiology should possess. The details of this projected axiology will, however, be left open. (shrink)

Recently, in his Rolf Schock Prize Lecture, Derek Parfit has suggested a novel way of avoiding the Repugnant Conclusion by introducing what he calls “imprecision” in value comparisons. He suggests that in a range of important cases, populations of different sizes are only imprecisely comparable. Parfit suggests that this feature of value comparisons opens up a way of avoiding the Repugnant Conclusion without implying other counterintuitive conclusions, and thus solves one of the major challenges in ethics. In this article, I (...) try to clarify Parfit’s proposal and evaluate whether it will help us with the paradoxes in population ethics. (shrink)

Act Utilitarianisms divide into Total and Average versions. Total versions seem to imply Parfit’s “Repugnant Conclusion”. Average versions are proposed in part to avoid the Repugnant Conclusion, but these are subject to “Mere Addition” arguments as detailed by Hudson in “The Diminishing Marginal Value of Happy People”. Thus, various intermediate versions of utilitarianism, such as the one investigated by Hurka in “Value and Population Size”, take on interest. But Hudson argues that such compromise theories are subject to the mere addition (...) arguments, and are therefore no improvement over Average Utilitarianism. I disagree: some such compromise solutions escape Hudson’s Mere Addition arguments. (shrink)

A set of arguments shows that either the Repugnant Conclusion and its variants are true or the better-than relation isn't transitive. Which is it? This is the most important question in population ethics. The answer will point the way to Parfit's elusive Theory X.

Critical-set views avoid the Repugnant Conclusion by subtracting some constant from the welfare score of each life in a population. These views are thus sensitive to facts about biographical identity: identity between lives. In this paper, I argue that questions of biographical identity give us reason to reject critical-set views and embrace the total view. I end with a practical implication. If we shift our credences towards the total view, we should also shift our efforts towards ensuring that humanity survives (...) for the long term. (shrink)

Nick Bostrom and others have suggested treating decision-making under moral uncertainty as analogous to parliamentary decision-making. The core suggestion of this “parliamentary approach” is that the competing moral theories function like delegates to the parliament, and that these delegates then make decisions by some combination of bargaining and voting. There seems some reason to hope that such an approach might avoid standard objections to existing approaches (for example, the “maximise expected choiceworthiness” (MEC) and “my favourite theory” approaches). However, the parliamentary (...) approach is so far extremely underspecified, making it largely indeterminate how such a model will in fact behave in the respects that those concerned with moral uncertainty care about. This paper explores one way of making it precise. We treat predicaments of moral uncertainty as analogous to bargaining situations alone (setting aside voting), and apply a version of the Nash solution that is standard in bargaining theory. The resulting model does indeed perform in many of the hoped-for ways. However, so also does a version of MEC that employs a structural approach to intertheoretic comparisons. It seems to us an open question which, regarding this version of MEC and the bargaining-theoretic approach, is superior to the other. We identify the key points on which the two differ. (shrink)

Is the overall value of a world just the sum of values contributed by each value-bearing entity in that world? Additively separable axiologies (like total utilitarianism, prioritarianism, and critical level views) say 'yes', but non-additive axiologies (like average utilitarianism, rank-discounted utilitarianism, and variable value views) say 'no'. This distinction appears to be practically important: among other things, additive axiologies generally assign great importance to large changes in population size, and therefore tend to strongly prioritize the long-term survival of humanity over (...) the interests of the present generation. Non-additive axiologies, on the other hand, need not assign great importance to large changes in population size. We show, however, that when there is a large enough `background population' unaffected by our choices, a wide range of non-additive axiologies converge in their implications with additive axiologies—for instance, average utilitarianism converges with critical-level utilitarianism and various egalitarian theories converge with prioritarianism. We further argue that real-world background populations may be large enough to make these limit results practically significant. This means that arguments from the scale of potential future populations for the astronomical importance of avoiding existential catastrophe, and other arguments in practical ethics that seem to presuppose additive separability, may succeed in practice whether or not we accept additive separability as a basic axiological principle. (shrink)

The issue of the time of intrinsic value focuses on the time during which a state has a level of intrinsic value. This is distinct from the time that desert makes a state of affairs good or bad (time of desert) and the time that statements about desert are true or false (time of the desert statement). To arrive at this conclusion, I assumed that intrinsic value is a function of desert-adjusted well-being. Both desert and well-being should be understood as (...) contemporaneous properties that occur at a particular moment in time. Hence, the time of intrinsic value is a point in time since the relevant property occurs at a point, albeit one that refers to the past. This result is significant because it relates to the dual-ledger account of intrinsic value. On one version of this account, desert is treated as similar to credits and well-being as similar to debits. It thus presents a tidy and intuitively appealing account of intrinsic value at a time and across times and persons. (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)