Adam Gurri writes:
Any chance you could do a post explaining Popper’s propensity theory of probability? I have never understood it.
My reply: I’m a big fan of Popper (search this blog for details), especially as interpreted by Lakatos, but as far as I can tell, Popper’s theory of probability is hopeless. We’ve made a lot of progress on probability in the past 75 years, and I don’t see any real need to go back to the bad old days.
Popper's propensity theory of probability (Popper, K. R. The propensity interpretation of probability,British Journal for the Philosophy of Science, 1959, 10, 25-42) was an attempt to provide an objective, single-case interpretation of probability, especially in quantum mechanics. Popper argued that the propensity theory avoided the well-documented defects emerging from the long-run frequency interpretation (See Hájek, A. Fifteen arguments against hypothetical frequentism, Erkenntnis, 2009). Unfortunately, the propensity interpretation is itself a failure (Humphreys, P. Why propensities cannot be probabilities, Philosophical Review, 1985, 94, 557-570; Eagle, A. Twenty-one arguments against propensity analyses of probability, Erkenntnis, 2004, 60, 371-416).