Simon Beard

One of Derek Parfit’s greatest legacies was the search for Theory X, a theory of population ethics that avoided all the implausible conclusions and paradoxes that have dogged the field since its inception: the Absurd Conclusion, the Repugnant Conclusion, the Non-Identity Problem, and the Mere Addition Paradox. In recent years, it has been argued that this search is doomed to failure and no satisfactory population axiology is possible. This chapter reviews Parfit’s life’s work in the field and argues that he provided all the necessary components necessary for a Theory X. It then shows how these components can be combined together and applied to the global challenges Parfit argued matter most: preventing human extinction, managing catastrophic risks, and eradicating global poverty and suffering. Finally, it identifies a number of challenges facing his theory and suggests how these may be overcome.

In this paper, we argue that our moral concern for future well-being should reduce over time due to important practical considerations about how humans interact with spacetime. After surveying several of these considerations (around equality, special duties, existential contingency, and overlapping moral concern) we develop a set of core principles that can both explain their moral significance and highlight why this is inherently bound up with our relationship with spacetime. These relate to the equitable distribution of (1) moral concern in a universe that we can only causally affect in one temporal direction; (2) access to the benefits from using spacetime as a resource; and (3) the burdens of care given (1) and (2). We conclude by considering the practical implications of our argument and find that, while it is often assumed that a preference for present over future well-being weakens the case for existential risk mitigation, this likely is not the case.

This paper examines and evaluates a range of methodologies that have been proposed for making useful claims about the probability of phenomena that would contribute to existential risk. Section One provides a brief discussion of the nature of such claims, the contexts in which they tend to be made and the kinds of probability that they can contain. Section Two provides an overview of the methodologies that have been developed to arrive at these probabilities and assesses their advantages and disadvantages. Section Three contains four suggestions to improve best practice in existential risk assessment. These suggestions centre on the types of probabilities used in risk assessment, the role of methodology rankings including the ranking of probabilistic information, the extended use of expert elicitation, and the use of confidence measures to better communicate uncertainty in probability assessments. Finally, Section Four provides an annotated literature review of catastrophic and existential risk probability claims as well as the methodologies that were used to produce each of them.

This paper examines and evaluates a range of methodologies that have been proposed for making useful claims about the probability of phenomena that would contribute to existential risk. Section One provides a brief discussion of the nature of such claims, the contexts in which they tend to be made and the kinds of probability that they can contain. Section Two provides an overview of the methodologies that have been developed to arrive at these probabilities and assesses their advantages and disadvantages. Section Three contains four suggestions to improve best practice in existential risk assessment. These suggestions centre on the types of probabilities used in risk assessment, the role of methodology rankings including the ranking of probabilistic information, the extended use of expert elicitation, and the use of confidence measures to better communicate uncertainty in probability assessments. Finally, Section Four provides an annotated literature review of catastrophic and existential risk probability claims as well as the methodologies that were used to produce each of them.

This paper examines and evaluates a range of methodologies that have been proposed for making useful claims about the probability of phenomena that would contribute to existential risk. Section One provides a brief discussion of the nature of such claims, the contexts in which they tend to be made and the kinds of probability that they can contain. Section Two provides an overview of the methodologies that have been developed to arrive at these probabilities and assesses their advantages and disadvantages. Section Three contains four suggestions to improve best practice in existential risk assessment. These suggestions centre on the types of probabilities used in risk assessment, the role of methodology rankings including the ranking of probabilistic information, the extended use of expert elicitation, and the use of confidence measures to better communicate uncertainty in probability assessments. Finally, Section Four provides an annotated literature review of catastrophic and existential risk probability claims as well as the methodologies that were used to produce each of them.

The Repugnant Conclusion and its paradoxes pose a significant problem for outcome evaluation. Derek Parfit has suggested that we may be able to resolve this problem by accepting a view he calls ‘Perfectionism’, which gives lexically superior value to ‘the best things in life’. In this paper, I explore perfectionism and its potential to solve this problem. I argue that perfectionism provides neither a sufficient means of avoiding the Repugnant Conclusion nor a full explanation of its repugnance. This is because even lives that are ‘barely worth living’ may contain the best things in life if they also contain sufficient ‘bad things’, such as suffering or frustration. Therefore, perfectionism can only fully explain or avoid the Repugnant Conclusion if combined with other claims, such as that bad things have an asymmetrical value relative to many good things. This combined view faces the objection that any such asymmetry implies Parfit’s ‘Ridiculous Conclusion’. However, I argue that perfectionism itself faces very similar objections, and that these are question-begging against both views. Finally, I show how the combined view that I propose not only explains and avoids the Repugnant Conclusion but also allows us to escape many of its paradoxes as well.

According to Luck egalitarians, fairness requires us to bring it about that nobody is worse off than others where this results from brute bad luck, but not where they choose or deserve to be so. In this paper, I consider one type of brute bad luck that appears paradigmatic of what a Luck Egalitarian ought to be most concerned about, namely that suffered by people who are born to badly off parents and are less well off as a result. However, when we consider what is supposedly unfair about this kind of unequal brute luck, luck egalitarians face a dilemma. According to the standard account of luck egalitarianism, differential brute luck is unfair because of its effects on the distribution of goods. Yet, where some parents are worse off because they have chosen to be imprudent, it may be impossible to neutralize these effects without creating a distribution that seems at least as unfair. This, I argue, is problematic for luck egalitarianism. I, therefore, explore two alternative views that can avoid this problem. On the first of these, proposed by Shlomi Segall, the distributional effects of unequal brute luck are unfair only when they make a situation more unequal, but not when they make it more equal. On the second, it is the unequal brute luck itself, rather than its distributional effects, that is unfair. I conclude with some considerations in favour of this second view, while accepting that both are valid responses to the problem I describe.

My thesis demonstrates that, despite a number of impossibility results, a satisfactory and coherent theory of population ethics is possible. It achieves this by exposing and undermining certain key assumptions that relate to the nature of welfare and personal identity. I analyse a range of arguments against the possibility of producing a satisfactory population axiology that have been proposed by Derek Parfit, Larry Temkin, Tyler Cowen and Gustaf Arrhenius. I conclude that these results pose a real and significant challenge. However, in the absence of further evidence I reject the conclusion that they imply that the value of populations is either not precise or not transitive. Instead, I expose some fundamental assumptions behind these results. One key assumption is that something can only make a life better or worse if it makes that life better or worse for the person living it, i.e. it raises or lowers the ‘welfare level’ of that life. Although intuitively highly plausible, this assumption ignores the possibility that perspectives other than that of the person living a life may be relevant for evaluating the components of that life and that these should be incorporated into our all things considered judgements. I argue that episodes within a person’s life that are strongly psychologically connected may have a special normative significance, particularly if these episodes involve such things as the enjoyment of ‘the best things in life’ or the experience of great suffering. We have reason to assign an all things considered value to such strongly psychologically connected phases of a person’s life, where this value is not exhausted by the contributions these make to the welfare level of that person’s life as a whole. It follows that our all things considered evaluations of populations are often underdetermined by information about the welfare levels of the lives they contain. However, in certain cases, most notably in that of ‘the Repugnant Conclusion’, there is nevertheless sufficient information provided by the welfare levels of persons’ lives to allow us to infer facts about these components that make an all things considered difference to these evaluations. I argue that a failure to acknowledge these facts is the cause of the aforementioned impossibility results and that once they are taken into account it is possible to produce a satisfactory theory of population ethics.