Speaker

Adam Elga

Adam Elga

Adam Elga is a Professor of Philosophy at Princeton University who works on rationality, probability and decision — how an agent should apportion belief and act when the evidence underdetermines the answer. Self-described as ‘addicted to rationality’, he is among the most cited philosophers on the puzzles where probability theory meets the strangeness of a large universe.

Elga’s best-known contributions sit at the join of epistemology and physics. His work on the Sleeping Beauty problem made the case for the ‘thirder’ position and helped set the terms of the modern debate over self-locating belief — uncertainty about who, when or where you are rather than about how the world is. He has written on Boltzmann brains and the self-undermining structure of typicality reasoning, on the direction of time and how present actions bear on past and future, and, with co-authors, on Dutch book arguments, money pumps and game-theoretic indecision. On rational disagreement he is associated with a version of the equal-weight view, developed alongside David Christensen’s writing, and with the paper ‘I can’t believe I’m stupid’ (with Andy Egan) on the limits of doubting one’s own opinions while still holding them.

Core positions

Elga holds that a rational agent must have some credence — some degree of belief — in every live possibility, because to act is to bet, and that these credences must cohere as probabilities or leave one open to a guaranteed loss. He treats self-locating uncertainty as genuine and answerable, favouring equal credence across indistinguishable copies within a world, and as a ‘thirder’ accepts that worlds containing more instances of one’s exact experience earn a probabilistic boost. He follows that commitment, reluctantly, into anthropic cosmology, granting that theories predicting more observers gain credence even as he worries this makes the reasoner ‘presumptuous’. On peer disagreement he argues you should defer to what your prior self would have expected about who was likelier to err, a discipline that exposes the quiet habit of always favouring oneself. Temperamentally conservative about bizarre conclusions, he resists them where he can but reports that the Boltzmann brain problem, in his view, largely survives every proposed escape.

In the wiki