•  5334
    Population axiology
    Philosophy Compass 12 (11). 2017.
    Population axiology is the study of the conditions under which one state of affairs is better than another, when the states of affairs in ques- tion may differ over the numbers and the identities of the persons who ever live. Extant theories include totalism, averagism, variable value theories, critical level theories, and “person-affecting” theories. Each of these the- ories is open to objections that are at least prima facie serious. A series of impossibility theorems shows that this is no coi…Read more
  •  4879
    Cluelessness
    Proceedings of the Aristotelian Society 116 (3): 311-339. 2016.
    Decisions, whether moral or prudential, should be guided at least in part by considerations of the consequences that would result from the various available actions. For any given action, however, the majority of its consequences are unpredictable at the time of decision. Many have worried that this leaves us, in some important sense, clueless. In this paper, I distinguish between ‘simple’ and ‘complex’ possible sources of cluelessness. In terms of this taxonomy, the majority of the existing lit…Read more
  •  1181
    Discounting for public policy: A survey
    Economics and Philosophy 33 (3): 391-439. 2017.
    This article is a critical survey of the debate over the value of the social discount rate, with a particular focus on climate change. The ma- jority of the material surveyed is from the economics rather than from the philosophy literature, but the emphasis of the survey itself is on founda- tions in ethical and other normative theory rather than highly technical details. I begin by locating the standard approach to discounting within the overall landscape of ethical theory, and explaining the a…Read more
  •  1116
    Moral uncertainty about population ethics
    with Toby Ord
    Journal of Ethics and Social Philosophy. forthcoming.
    Given the deep disagreement surrounding population axiology, one should remain uncertain about which theory is best. However, this uncertainty need not leave one neutral about which acts are better or worse. We show that as the number of lives at stake grows, the Expected Moral Value approach to axiological uncertainty systematically pushes one towards choosing the option preferred by the Total and Critical Level views, even if one’s credence in those theories is low.
  •  1075
    What Should We Agree on about the Repugnant Conclusion?
    with Stephane Zuber, Nikhil Venkatesh, Torbjörn Tännsjö, Christian Tarsney, H. Orri Stefánsson, Katie Steele, Dean Spears, Jeff Sebo, Marcus Pivato, Toby Ord, Yew-Kwang Ng, Michal Masny, William MacAskill, Nicholas Lawson, Kevin Kuruc, Michelle Hutchinson, Johan E. Gustafsson, Lisa Forsberg, Marc Fleurbaey, Diane Coffey, Susumu Cato, Clinton Castro, Tim Campbell, Mark Budolfson, John Broome, Alexander Berger, Nick Beckstead, and Geir B. Asheim
    Utilitas 33 (4): 379-383. 2021.
    The Repugnant Conclusion served an important purpose in catalyzing and inspiring the pioneering stage of population ethics research. We believe, however, that the Repugnant Conclusion now receives too much focus. Avoiding the Repugnant Conclusion should no longer be the central goal driving population ethics research, despite its importance to the fundamental accomplishments of the existing literature.
  •  1064
    This chapter makes the case for strong longtermism: the claim that, in many situations, impact on the long-run future is the most important feature of our actions. Our case begins with the observation that an astronomical number of people could exist in the aeons to come. Even on conservative estimates, the expected future population is enormous. We then add a moral claim: all the consequences of our actions matter. In particular, the moral importance of what happens does not depend on when it h…Read more
  •  746
    Global consequentialism and the morality and laws of war
    In McDermott and Roser Kuosmanen (ed.), Human rights and 21st century challenges, Oxford University Press. forthcoming.
    Rights-based approaches and consequentialist approaches to ethics are often seen as being diametrically opposed to one another. In one sense, they are. In another sense, however, they can be reconciled: a ‘global’ form of consequentialism might supply consequentialist foundations for a derivative morality that is non-consequentialist, and perhaps rights-based, in content. By way of case study to illustrate how this might work, I survey what a global consequentialist should think about a recent d…Read more
  •  699
    According to Bayesian epistemology, the epistemically rational agent updates her beliefs by conditionalization: that is, her posterior subjective probability after taking account of evidence X, pnew, is to be set equal to her prior conditional probability pold(·|X). Bayesians can be challenged to provide a justification for their claim that conditionalization is recommended by rationality—whence the normative force of the injunction to conditionalize? There are several existing justifications fo…Read more
  •  697
    Extended Preferences and Interpersonal Comparisons of Well‐being
    Philosophy and Phenomenological Research 96 (3): 636-667. 2016.
    An important objection to preference-satisfaction theories of well-being is that these theories cannot make sense of interpersonal comparisons of well-being. A tradition dating back to Harsanyi () attempts to respond to this objection by appeal to so-called extended preferences: very roughly, preferences over situations whose description includes agents’ preferences. This paper examines the prospects for defending the preference-satisfaction theory via this extended preferences program. We argue…Read more
  •  548
    Aggregating extended preferences
    Philosophical Studies 174 (5): 1163-1190. 2017.
    An important objection to preference-satisfaction theories of well-being is that they cannot make sense of interpersonal comparisons. A tradition dating back to Harsanyi :434, 1953) attempts to solve this problem by appeal to people’s so-called extended preferences. This paper presents a new problem for the extended preferences program, related to Arrow’s celebrated impossibility theorem. We consider three ways in which the extended-preference theorist might avoid this problem, and recommend tha…Read more
  •  496
    Discounting future health
    In Norheim Emanuel Jamison Johansson Millum Otterson Ruger and Verguet (ed.), Global health priority-setting: Cost-effectiveness and beyond, Oxford University Press. forthcoming.
    In carrying out cost-benefit or cost-effective analysis, a discount rate should be applied to some kinds of future benefits and costs. It is controversial, though, whether future health is in this class. I argue that one of the standard arguments for discounting (from diminishing marginal returns) is inapplicable to the case of health, while another (favouring a pure rate of time preference) is unsound in any case. However, there are two other reasons that might support a positive discount rate …Read more
  •  491
    Harsanyi claimed that his Aggregation and Impartial Observer Theorems provide a justification for utilitarianism. This claim has been strongly resisted, notably by Sen and Weymark, who argue that while Harsanyi has perhaps shown that overall good is a linear sum of individuals’ von Neumann-Morgenstern utilities, he has done nothing to establish any con- nection between the notion of von Neumann-Morgenstern utility and that of well-being, and hence that utilitarianism does not follow. The present…Read more
  •  468
    Against "the badness of death"
    In Espen Gamlund & Carl Tollef Solberg (eds.), Saving People from the Harm of Death, Oxford University Press. 2019.
    I argue that excessive reliance on the notion of “the badness of death” tends to lead theorists astray when thinking about healthcare prioritisation. I survey two examples: the confusion surrounding the “time-relative interests account” of the badness of death, and a confusion in the recent literature on cost-benefit analyses for family planning interventions. In both cases, the confusions in question would have been avoided if (instead of attempting to theorise in terms of the badness of death)…Read more
  •  455
    Epistemic Decision Theory
    Mind 122 (488): 915-952. 2013.
    I explore the prospects for modelling epistemic rationality (in the probabilist setting) via an epistemic decision theory, in a consequentialist spirit. Previous work has focused on cases in which the truth-values of the propositions in which the agent is selecting credences do not depend, either causally or merely evidentially, on the agent’s choice of credences. Relaxing that restriction leads to a proliferation of puzzle cases and theories to deal with them, including epistemic analogues of e…Read more
  •  370
    Probability in the Everett interpretation
    Philosophy Compass 2 (1). 2007.
    The Everett (many-worlds) interpretation of quantum mechanics faces a prima facie problem concerning quantum probabilities. Research in this area has been fast-paced over the last few years, following a controversial suggestion by David Deutsch that decision theory can solve the problem. This article provides a non-technical introduction to the decision-theoretic program, and a sketch of the current state of the debate.
  •  328
    Time Reversal in Classical Electromagnetism
    British Journal for the Philosophy of Science 60 (3): 557-584. 2009.
    Richard Feynman has claimed that anti-particles are nothing but particles `propagating backwards in time'; that time reversing a particle state always turns it into the corresponding anti-particle state. According to standard quantum field theory textbooks this is not so: time reversal does not turn particles into anti-particles. Feynman's view is interesting because, in particular, it suggests a nonstandard, and possibly illuminating, interpretation of the CPT theorem. In this paper, we explore…Read more
  •  326
    Overpopulation is often identified as one of the key drivers of climate change. Further, it is often thought that the mechanism behind this is obvious: 'more people means more greenhouse gas emissions'. However, in light of the fact that climate change depends most closely on cumulative emissions rather than on emissions rates, the relationship between population size and climate change is more subtle than this. Reducing the size of instantaneous populations can fruitfully be thought of as sprea…Read more
  •  319
    The social disvalue of premature deaths
    In Iwao Hirose & Andrew Reisner (eds.), Weighing and reasoning: Themes from the philosophy of John Broome, Oxford University Press. 2015.
    Much public policy analysis requires us to place a monetary value on the bad- ness of a premature human death. Currently dominant approaches to determining this ‘value of a life’ focus exclusively on the ‘self-regarding’ value of life — that is, the value of a person’s life to the person whose death is in question — and altogether ignore effects on other people. This procedure would be justified if, as seems intuitively plausible, other-regarding effects were negligible in comparison with self-r…Read more
  •  317
    Understanding Deutsch's probability in a deterministic universe
    Studies in History and Philosophy of Modern Physics 35 (3): 423-456. 2004.
    Difficulties over probability have often been considered fatal to the Everett interpretation of quantum mechanics. Here I argue that the Everettian can have everything she needs from `probability' without recourse to indeterminism, ignorance, primitive identity over time or subjective uncertainty: all she needs is a particular *rationality principle*. The decision-theoretic approach recently developed by Deutsch and Wallace claims to provide just such a principle. But, according to Wallace, deci…Read more
  •  243
    Empirical Consequences of Symmetries
    with David Wallace and Hilary Greaves
    British Journal for the Philosophy of Science 65 (1): 59-89. 2014.
    It is widely recognized that ‘global’ symmetries, such as the boost invariance of classical mechanics and special relativity, can give rise to direct empirical counterparts such as the Galileo-ship phenomenon. However, conventional wisdom holds that ‘local’ symmetries, such as the diffeomorphism invariance of general relativity and the gauge invariance of classical electromagnetism, have no such direct empirical counterparts. We argue against this conventional wisdom. We develop a framework for …Read more
  •  195
    Antiprioritarianism
    Utilitas 27 (1): 1-42. 2015.
    Prioritarianism is supposed to be a theory of the overall good that captures the common intuition of . But it is difficult to give precise content to the prioritarian claim. Over the past few decades, prioritarians have increasingly responded to this by formulating prioritarianism not in terms of an alleged primitive notion of quantity of well-being, but instead in terms of von NeumannPrimitivistTechnicalpriority to the worse offMorgenstern utility is a retrograde step
  •  185
    Effective Altruism: Philosophical Issues (edited book)
    Oxford University Press. 2019.
    This is the first collective study of the thinking behind the effective altruism movement. This movement comprises a growing global community of people who organise significant parts of their lives around the two key concepts represented in its name. Altruism is the idea that if we use a significant portion of the resources in our possession—whether money, time, or talents—with a view to helping others then we can improve the world considerably. When we do put such resources to altruistic use, i…Read more
  •  185
    Towards a geometrical understanding of the cpt theorem
    British Journal for the Philosophy of Science 61 (1): 27-50. 2010.
    The CPT theorem of quantum field theory states that any relativistic (Lorentz-invariant) quantum field theory must also be invariant under CPT, the composition of charge conjugation, parity reversal and time reversal. This paper sketches a puzzle that seems to arise when one puts the existence of this sort of theorem alongside a standard way of thinking about symmetries, according to which spacetime symmetries (at any rate) are associated with features of the spacetime structure. The puzzle is, …Read more
  •  182
    On the Everettian epistemic problem
    Studies in History and Philosophy of Modern Physics 38 (1): 120-152. 2006.
    Recent work in the Everett interpretation has suggested that the problem of probability can be solved by understanding probability in terms of rationality. However, there are *two* problems relating to probability in Everett --- one practical, the other epistemic --- and the rationality-based program *directly* addresses only the practical problem. One might therefore worry that the problem of probability is only `half solved' by this approach. This paper aims to dispel that worry: a solution to…Read more
  •  162
    True benevolence is, most fundamentally, a desire that the world be better. It is natural and common, however, to frame thinking about benevolence indirectly, in terms of a desire to make a difference to how good the world is. This would be an innocuous shift if desires to make a difference were extensionally equivalent to desires that the world be better. This paper shows that at least on some common ways of making a “desire to make a difference” precise, this extensional equivalence fails. Whe…Read more
  •  144
    In search of (spacetime) structuralism
    Philosophical Perspectives 25 (1): 189-204. 2011.
  •  136
    Everett and evidence
    In Simon Saunders, Jonathan Barrett, Adrian Kent & David Wallace (eds.), Many Worlds?: Everett, Quantum Theory & Reality, Oxford University Press. 2010.
    Much of the evidence for quantum mechanics is statistical in nature. The Everett interpretation, if it is to be a candidate for serious consideration, must be capable of doing justice to reasoning on which statistical evidence in which observed relative frequencies that closely match calculated probabilities counts as evidence in favour of a theory from which the probabilities are calculated. Since, on the Everett interpretation, all outcomes with nonzero amplitude are actualized on different bra…Read more
  •  82
    On the CPT theorem
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 45 46-65. 2014.
    We provide a careful development and rigorous proof of the CPT theorem within the framework of mainstream quantum field theory. This is in contrast to the usual rigorous proofs in purely axiomatic frameworks, and non-rigorous proof-sketches in the mainstream approach. We construct the CPT transformation for a general field directly, without appealing to the enumerative classification of representations, and in a manner that is clearly related to the requirements of our proof. Our approach applie…Read more
  •  75
    Moral Uncertainty About Population Axiology
    with Toby Ord
    Journal of Ethics and Social Philosophy 12 (2): 135-167. 2017.
    Given the deep disagreement surrounding population axiology, one should remain uncertain about which theory is best. However, this uncertainty need not leave one neutral about which acts are better or worse. We show that, as the number of lives at stake grows, the Expected Moral Value approach to axiological uncertainty systematically pushes one toward choosing the option preferred by the Total View and critical-level views, even if one’s credence in those theories is low.