Evaluating strong longtermism

Abstract

Roughly, strong longtermism (Greaves and MacAskill 2021) is the view that in the most important decision-situations facing us today, the option that is ex ante best, and the one we ought to choose, is the option that makes the far future go best. The purpose of this thesis is to evaluate strong longtermism. I do this by first considering what I take to be three important objections to this view, and then suggesting a way in which the strong longtermist may be able to respond to them. The thesis consists of five chapters. In Chapter 1, I introduce the topic of the thesis and reconstruct Greaves and MacAskill’s argument for strong longtermism. In Chapter 2, I argue that partially aggregative and non-aggregative moral views form a significant objection to Greaves and MacAskill’s argument for deontic strong longtermism. In Chapter 3, I discuss the procreative asymmetry, arguing that what I call the Purely Deontic Asymmetry forms another important objection to strong longtermism. In Chapter 4, I consider the problem of fanaticism, arguing that the best way those in favour of strong longtermism can avoid this problem is by adopting a view called tail discounting. Finally, in Chapter 5, I propose that the issues discussed in the preceding chapters can be satisfactorily dealt with by framing strong longtermism as a public philosophy. This means that we should understand strong longtermism as a view that correctly describes what state-level actors ought to do, rather than as a blueprint for individual morality. If my evaluation is correct, then there are important limits to the role that strong longtermism can play in our private lives. However, it also implies that as a society, we ought to do much more than we currently do to safeguard the long-term future of humanity.