Joe Horton

I am an associate professor in philosophy at University College London and an associate editor at Mind and Philosophy & Public Affairs.

I work mainly on issues in ethics and political philosophy, but I am also interested in rationality and epistemology. My recent work focuses on questions about interpersonal aggregation, suboptimal supererogation, exploitation, the procreation asymmetry, evaluative uncertainty, and decision instability.

You can contact me at joe.horton@ucl.ac.uk. You can find my CV here.

You can find my published work through the following links:

1. Hindsight and Decision Instability, Australasian Journal of Philosophy (forthcoming)     (abstract)

There has recently been a surge of interest in a new kind of decision theory, which we can call Hindsight Decision Theory (HDT). Its proponents include Ralph Wedgwood, J. Dmitri. Gallow, Abelard Podgorski, and David James Barnett. They argue that HDT avoids problems with both Evidential Decision Theory (EDT) and Causal Decision Theory (CDT). I here argue that the main problem with EDT, known as the Newcomb Problem, also applies, with no less force, to HDT. I then address the main problem with CDT, which is that it seems to generate a counterintuitive kind of decision instability. I argue that decision instability can be avoided by combining CDT with a natural constraint on options.

2. Contrary-to-Duty Permission and Deontic Quantification, Analysis (forthcoming)     (abstract)

There are well-known puzzles that arise when contrary-to-duty obligations are subjected to modus ponens. But there is another puzzling feature of these obligations that has not received any attention—they do not entail contrary-to-duty permissions. I aim to bring this puzzle under the spotlight by demonstrating its generality and depth, showing that the most natural ways of deflating it are unsatisfying, and indicating its relevance to theorizing about the semantics of the deontic terms.

3. Evaluative Uncertainty, The Oxford Handbook of Normative Ethics (2026)     ––with Jacob Ross––     (abstract)

Note: An error in the printing of this handbook resulted in the first paragaph of our chapter being replaced by a different paragraph (a paragraph summarising our chapter for the introduction to the handbook). This error has been corrected in the online version of the book and in the PDF linked here.

This chapter concerns evaluative uncertainty—uncertainty about values or objective reasons for action. It argues, against some recent sceptics, that evaluative uncertainty is relevant to rational and moral choice. It considers a number of principles from the literature aimed at precisifying this relevance, shows that they all face serious objections, and then proposes alternative principles that avoid these objections. It also discusses two important challenges, known as the problem of intertheoretic value comparison and the problem of fanaticism. The main conclusion of the chapter is that, while a theory of rational and moral choice under evaluative uncertainty is needed, no special theory is needed, because the dominant theory of rational choice under ordinary uncertainty can be extended to rational and moral choice under evaluative uncertainty.

4. Evaluative Uncertainty and Permissible Preference, The Philosophical Review 134 (2025): 35–64     ––with Jacob Ross––     (abstract)

There has recently been an explosion of interest in rational and moral choice under evaluative uncertainty—uncertainty about values or reasons. However, the dominant views on such choice have at least three major problems: they are overly demanding, they are incompatible with supererogation, and they cannot be applied to agents with credence in indeterminate evaluative theories. We here propose a unified view that solves all these problems. According to this view, permissible options maximise expected utility relative to permissible preferences, and different kinds of permissibility for options correspond to different kinds of permissibility for preferences. Thus, rationally permissible options maximize expected utility relative to rationally permissible preferences, and morally permissible options maximize expected utility relative to morally permissible preferences. We argue that this view has more plausible implications than its rivals not only under evaluative uncertainty but also under ordinary uncertainty.

5. Supererogation, Conditional Obligation, and the All or Nothing Problem, Handbook of Supererogation (2023): 51–61     (abstract)

If doing good is often beyond the call of duty, instances of the All or Nothing Problem abound. I have argued elsewhere that we should solve this problem by accepting a principle that I call Optimific Altruism, which has interesting implications both for the correct account of supererogation and for our obligations to give to charity. However, Theron Pummer and Daniel Muñoz have argued that we should instead solve this problem by rejecting an inference rule that I call Conditional Obligation. I here recap my preferred solution and argue against this alternative.

6. New and Improvable Lives, The Journal of Philosophy 118 (2021): 486–503     (abstract)

According to weak utilitarianism, at least when other things are equal, you should maximize the sum of well-being. This view has much explanatory power, but it also has two implications that seem to me implausible. First, it implies that, other things equal, it is wrong to harm yourself, or even to deny yourself benefits. Second, it implies that, other things equal, given the opportunity to create new happy people, it is wrong not to. These implications can be avoided by accepting a complaints-based alternative to weak utilitarianism. However, complaints-based views face two decisive problems, originally noticed by Jacob Ross. I here develop a view that avoids these problems while retaining the advantages of complaints-based views.

7. Partial Aggregation in Ethics, Philosophy Compass 16 (2021): 1–12     (abstract)

Is there any number of people you should save from paralysis rather than saving one person from death? Is there any number of people you should save from a migraine rather than saving one person from death? Many people answer ‘yes’ and ‘no’, respectively. The aim of partially aggregative moral views is to capture and justify combinations of intuitions like these. These views contrast with fully aggregative moral views, which imply that the answer to both questions is ‘yes’, and with non-aggregative moral views, which imply that the answer to both questions is ‘no’. In this paper, I review the most natural and influential ways of developing partially aggregative views and explain the main problems they face.

8. Aggregation, Risk, and Reductio, Ethics 130 (2020): 514–529     (abstract)

Is there any number of people you should save from paralysis rather than saving one person from death? Is there any number of people you should save from a migraine rather than saving one person from death? Many people answer ‘yes’ and ‘no’, respectively. The aim of partially aggregative moral views is to capture and justify combinations of intuitions like these. These views contrast with fully aggregative moral views, which imply that the answer to both questions is ‘yes’, and with non-aggregative moral views, which imply that the answer to both questions is ‘no’. In this paper, I develop a risk-based reductio argument that shows there can be no adequate partially aggregative view. I then argue that the only plausible response to this reductio is to accept a fully aggregative view.

9. The Exploitation Problem, The Journal of Political Philosophy 27 (2019): 469–479     (abstract)

Many of us believe that exploitation is wrong, and that it is wrong even when, because the exploited would otherwise suffer, they consent to the exploitation. Does it follow that we should leave people to suffer rather than exploit them? This conclusion might seem difficult to accept, but avoiding it seems to require accepting a counterintuitively demanding view about our obligations to vulnerable people. In this paper, I offer a new solution to this problem.

10. Always Aggregate, Philosophy & Public Affairs 46 (2018): 160–174     (abstract)

Is there any number of people you should save from paralysis rather than saving one person from death? Is there any number of people you should save from a headache rather than saving one person from death? Many people answer ‘yes’ and ‘no’, respectively. They therefore accept a partially aggregative moral view. Patrick Tomlin has recently argued that the most promising partially aggregative views in the literature have implausible implications in certain cases in which there are additions or subtractions to the groups of people that we can save. Several philosophers have begun responding to this argument by developing partially aggregative views that avoid the relevant implications. In this paper, I extend Tomlin’s argument to create a dilemma that no partially aggregative view can avoid. I conclude that we should accept a fully aggregative moral view.

11. Aggregation, Complaints, and Risk, Philosophy & Public Affairs 45 (2017): 54–81     (abstract)

Several philosophers have defended versions of Minimax Complaint, or MC. According to MC, other things equal, we should act in the way that minimises the strongest individual complaint. In this paper, I argue that MC must be rejected because it has implausible implications in certain cases involving risk. In these cases, we can apply MC either ex ante, by focusing on the complaints that could be made based on the prospects that an act gives to people, or ex post, by focusing on the complaints that could be made based on the actual results that an act has for people. I argue that MC has implausible implications either way. I then defend a view on which, other things equal, we should act in the way that minimizes the sum of complaints.

12. The All or Nothing Problem, The Journal of Philosophy 114 (2017): 94–104     (abstract)

There are many cases in which, by making some great sacrifice, you could bring about either a good outcome or a very good outcome. In some of these cases, it seems wrong for you to bring about the good outcome, since you could bring about the very good outcome with no additional sacrifice. It also seems permissible for you not to make the sacrifice, and bring about neither outcome. But together, these claims seem to imply that you ought to bring about neither outcome rather than the good outcome. And that seems very counterintuitive. In this paper, I develop this problem, propose a solution, and then draw out some implications both for how we should understand supererogation and for how we should approach charitable giving.

I currently teach the following courses:

1. Topics in Political Philosophy (2nd-year)     (description)

This course investigates questions that are both central to political philosophy and of current political importance. They include: What does it take for a political system to be just? Can we support equality of opportunity without also supporting equality of outcome? How can we come to own natural resources? Does global inequality matter as much as national inequality? Are we obligated to obey the law? Is it wrong to contribute to climate change? What do we owe to future generations?

2. Consequentialism, Kantianism, and the Ideal World (3rd-year, MA, MPhil)     (description)

Consequentialism and Kantianism are two of the most influential theories of morality. In this course, we consider their various formulations, their strengths and weaknesses, and the distance between them.

3. The Philosophy of Altruism (3rd-year, MA, MPhil)     (description)

This course investigates questions about altruism. They include: Are we obligated to give to charity? Is it wrong to give to suboptimal charities? Should we be vegetarians? Is it wrong to buy clothes made in sweatshops? Is ethical consumerism an impermissible form of vigilantism? Is it wrong to contribute to collective harms, such as climate change? What do we owe to future generations?

4. Recent Work in Moral Philosophy (MPhil)     (description)

This course introduces students to recent work in moral philosophy. We cover five topics each term, with two seminars dedicated to each topic.