Episode Summary
Executive Summary: Hilary Greaves discusses her shift from philosophy of physics to moral philosophy, her work on decision theory, population ethics, moral uncertainty, longtermism, and cluelessness, and how these ideas shape Global Priorities Institute’s research agenda. The episode also doubles as a practical overview of GPI’s hiring, visiting, scholarship, and fundraising priorities, especially for philosophy and economics talent interested in high-impact research.
Main Topics: Greaves’s Research Shift and Current Agenda: Greaves explains moving from philosophy of physics and quantum mechanics to moral philosophy and global priorities, motivated by practical questions about action, value, and policy. She outlines three current papers: moral uncertainty (parliamentary model), extinction-risk/longtermism, and cost-benefit analysis weighting. Decision Theory and Epistemic Rationality: A large section explores causal vs evidential decision theory via Newcomb’s problem, smoking lesion, and psychopath button cases, then analogizes these debates to epistemic decision theory and the difficulty of modeling epistemic rationality as an outcome-maximization problem. Longtermism, Discounting, and Population Ethics: Greaves defends the philosophical importance of the far future, argues against discounting future welfare, and reviews population ethics debates including total utilitarianism, average utilitarianism, person-affecting views, and the repugnant conclusion. Moral Uncertainty and the Parliamentary Model: She describes the appeal of the parliamentary approach to moral uncertainty as an alternative to simple expected-value maximization, especially when theories are structurally different or when one wants to hedge between theories, though her formalization did not outperform expected-value methods. Cluelessness and Charity Evaluation: Greaves argues that long-run effects of interventions can dominate short-run effects and be highly uncertain, challenging reliance on measurable impact-evaluation metrics alone. This complicates cross-cause comparisons and charity selection. Global Priorities Institute’s Research Strategy and Hiring: The interview closes with GPI’s plans to expand economics capacity, hire operations staff, support graduate visitors and scholarships, and encourage academically rigorous work on EA-relevant questions through collaboration, funding, and publication.
Key Arguments: Greaves’s move away from philosophy of physics was driven by a desire to work on questions tied to real-world practical reasoning rather than continuing an academic publication treadmill in a field she no longer found central to her motivations. Many probabilistic worries about many-worlds quantum mechanics are, in her view, resolved by decision-theoretic considerations: what matters is rational weighting of branches, not classical chance in the usual sense. Causal decision theory is her preferred practical decision theory, but she emphasizes that precommitting to evidential decision theory can be rational in some circumstances because precommitment is a different act from later following the theory. Epistemic rationality may not be well modeled as a consequentialist maximize-truth/accuracy problem; attempts to create an epistemic analogue of decision theory run into counterintuitive cases. Longtermism becomes compelling once one rejects discounting future welfare and accepts plausible population ethics views that treat future lives as morally significant. Population ethics appears structurally unable to satisfy all intuitive desiderata at once, so one must choose among imperfect theories and accept some “poison pill” like the repugnant conclusion or other counterintuitive results. The parliamentary model of moral uncertainty is attractive in principle, but a bargaining-theory formalization does not obviously improve on expected moral value and may still behave awkwardly. Cluelessness is not just ignorance about future effects; it is a deeper problem that our best-known near-term evaluations may be swamped by uncertain, unmeasured long-run effects that do not conveniently cancel out. Impact evaluations like GiveWell’s are useful only if the long-run effects largely travel through the measured causal pathway and preserve the sign of the intervention’s value; otherwise they may badly mislead. Risk aversion, when properly specified, can actually strengthen the case for extinction-risk reduction rather than weaken it, because extinction is a worst-case outcome in the space of future value.
Data Points: Job contract length: 4 years - Head of research operations role at GPI Operations role salary: £40,000–£49,000 per year - Announced in the opening recruitment pitch Research visitor program: Summer 2019 - Economics PhD students and early-career researchers invited to visit GPI Visitor application deadline: 30th of November - Deadline for the summer research visitor program Operations application deadline: 19th of November - Deadline for head of research operations role GPI research agenda size: ~50 pages - Initial internal list of potential research topics Greaves’s pipeline: 3 papers - She says she currently has three EA-motivated papers in progress Quantum interpretation duration: 10 years - She says she has been out of philosophy of physics for about a decade Current GPI team size: about 4 full-time philosophers - Describing the institute’s early staffing and philosophy-heavy composition Summer visitor cohort: ~12 graduate students per summer - Typical number of graduate visitors at GPI Departmental support gap: 2 years of default PhD funding - Used to explain why GPI scholarships are needed to top up Oxford funding packages Philosophy students at summer program: all philosophy slots filled early - For the 2019 summer visitor program; economics had remaining capacity Economics slots remaining: half of slots still open - Second round of applications available for economics visitors
Pivotal Quotes: "If you're not working on the things that you're excited about or the things that you think are important, then you might as well not be in academia." — Hilary Greaves: Explaining why she changed research fields and why major shifts can be worth the career risk "I think the following thing is the case. For any decision theory you can write down in the practical case, you can write down a structurally analogous decision theory in the epistemic case." — Hilary Greaves: Summarizing the structure of her work on epistemic decision theory and its limits "The point is not for me to change the world, the point is for the world to get changed." — Hilary Greaves: Describing the collaborative culture at GPI and why it differs from typical academic incentives
Implications: The episode makes a strong case for more rigorous academic work on longtermism, moral uncertainty, and population ethics, while also showing why GPI wants more philosophers, economists, and ops talent. For listeners, it’s a roadmap for high-impact research careers and funding priorities.