In this episode, we speak with Dr. David Thorstad: Assistant Professor of Philosophy at Vanderbilt University, Senior Research Affiliate at the Global Priorities Institute, and author of the blog, Reflective Altruism. We discuss existential risks–threats that could permanently destroy or drastically curtail humanity’s future–and how we should reason about these risks under significant uncertainty.

(00:00) Our introduction

(09:32) Interview begins

(14:32) The longtermism shift

(23:17) Framework for objections to longtermism

(29:47) Overestimating existential risk: population dynamics

(36:06) Overestimating existential risk: cumulative vs. period risk

(39:44) Overestimating existential risk: ignoring background risk

(42:14) The time of perils hypothesis

(46:11) When and where should philosophers speculate?

(1:09:02) Extraordinary claims require extraordinary evidence

(1:21:44) Regression to the inscrutable and the preface paradox

(1:30:07) The tendency to quantify

Used or referenced:

• David’s blog, Reflective Altruism
• Thorstad, “Three mistakes in the moral mathematics of existential risk”
• Thorstad, “High risk, low reward”
• Thorstad, “Against the singularity hypothesis”
• Parfit, Reasons and Persons (p. 453)
• MacAskill, What We Owe The Future
• Ord, The Precipice
• Berger, Open Philanthropy, “Our Progress in 2023 and Plans for 2024”
• 80,000 Hours, “What are the world’s most pressing problems?”
• Maule (EA Forum), “Historical EA Funding Data”
• Elsey and Moss (EA Forum), “EA Survey: Cause Prioritization”
• Ord (EA Forum), “The Precipice Revisited”
• Greaves and MacAskill, “The case for strong longtermism”
• EA Critiques Podcast, “Astronomical Value, Existential Risk, and Billionaire Philanthropy with David Thorstad”
• Forecasting Research Institute, “Results from the 2022 Existential Risk Persuasion Tournament”
• Coleman et al., “Beliefs about the end of humanity: How bad, likely, and important is human extinction?”
• Turner et al. (NeurIPS), “Optimal policies tend to seek power”

Bio(un)ethical is a bioethics podcast written by Leah Pierson and Sophie Gibert, with editing and production by Ambedo Media (previous production support by Audiolift.co). Our music is written by Nina Khoury and performed by Social Skills. We are supported by a grant from Amplify Creative Grants.