Question

Which interpretations of probability take probability to be epistemic (subjective) and which take it to be ontological (objective).

Answer 1

Epistemic probabilities are logical probabilities, that is, unique, rational degrees of belief dictated by the information at our disposal, or they may be viewed as subjective, that is, internally consistent sets of beliefs or preferences that are not, however, uniquely determined; or they may be regarded as purely psychological, descriptive of actual belief, but free of any normative constraint. These probabilities are subjective because people have different bodies of evidence.

Physical probabilities, which are also called objective or frequency probabilities, are associated with random physical systems such as roulette wheels, rolling dice, and radioactive atoms. In such systems, a given type of event (such as a die yielding a six) tends to occur at a persistent rate, or "relative frequency", in a long run of trials. Physical probabilities either explain or are invoked to explain, these stable frequencies. They may be thought of as either frequencies, finite or infinite, descriptive of outcomes observed over a series of “identical” trials, etc