2023/04/01 by David Wallace · 5 citations
Arts and Humanities · Physics and Astronomy · #Artificial intelligence #Bayesian probability #Computer science #Epistemology #Epistemology, Ethics, and Metaphysics #Philosophy #Philosophy and History of Science #Quantum Mechanics and Applications
paper · doi:10.1093/analys/anac096
published in Analysis 83(2), 295-298 (Oxford University Press)
openalex publication_date 2023/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
Some theories in physics seem to be ‘self-undermining’: that is, if they are correct, we are probably mistaken about the evidence that apparently supports them. For instance, certain cosmological theories have the apparent consequence that most observers are so-called ‘Boltzmann brains’, which exist only momentarily and whose apparent experiences and memories are not veridical. I provide a Bayesian analysis to demonstrate why theories of this kind are not after all supported by the apparent evidence in their favour, taking advantage of the split between ‘primary evidence’, which directly supports a theory, and ‘proximal evidence’, which is our evidence (largely records and testimony) for the primary evidence. Certain contexts in physics generate what David Albert (2000) has called cognitive instability, or an argument that a theory is what we might call self-undermining. The abstract form of such an argument is: the evidence supports theory T, but conditional on theory T, it is extremely likely that I am mistaken about the evidence.