The propensity theory of probability was developed by Karl Popper (1957, 1959 and 1990), although a number of versions exist today.
Popper criticised von Mises’ frequency theory as being unable to deal with the probability of single events (Gillies 2000: 115).
Popper held that a new theory was necessary and he conceptualised probability as a tendency or propensity of certain processes or phenomena to produce objective probabilities (Gillies 2000: 115–116), though Popper’s (1990) later version of the propensity theory differs from his earlier one (Gillies 2000: 126) (and this theory was developed by Miller 1994 and 1995).
Though Popper seemed to think that some single events can have objectively determined probabilities, Gillies (2000: 120–124) argues that many single event probabilities cannot be “fully objective,” owing to the reference class problem, except perhaps in games of chance. Therefore Gillies rejects Popper’s early propensity theory.
But Popper’s early propensity theory of both long-run and single-case probabilities is, however, not the only such theory, and Gillies (2000: 126) divides modern propensity theories into two classes:
(1) long-run propensity theories, andGillies (2000: 136) has developed and defended his own version of a long-run propensity theory of probability, which he sees as the best interpretation of objective probabilities.
(2) single-case propensity theories (Gillies 2000: 126).
“Interpretations of Probability,” Stanford Encyclopedia of Philosophy, 2002 (rev. 2011)
Gillies, D. A. 2000. Philosophical Theories of Probability. Routledge, London.
Miller, David. 1994. Critical Rationalism: A Restatement and Defence. Open Court, Chicago.
Miller, David. 1995. “Propensities and Indeterminism,” in A. O’Hear (ed.), Karl Popper: Philosophy and Problems. Cambridge University Press, Cambridge. 121–147.
Popper, Karl R. 1957. “The Propensity Interpretation of the Calculus of Probability, and the Quantum Theory,” in S. Körner (ed.), Observation and Interpretation: A Symposium of Philosophers and Physicists: Proceedings of the Ninth Symposium of the Colston Research Society, held in the University of Bristol, April 1st–April 4th, 1957. Butterworths, London. 65–70.
Popper, Karl R. 1959. “The Propensity Interpretation of Probability,” British Journal for the Philosophy of Science 10: 25–42.
Popper, Karl R. 1990. A World of Propensities. Thoemmes, Bristol.