Physical Probability vs. Probability in Physics

Peter Lukan
Faculty of Arts, University of Ljubljana

In my presentation I discuss the differences between different concepts of probability used in physics. I first focus is on the difference between classical (combinatorial), frequentist and measure-theoretic concepts of probability. Then I try to define how we can regard probability in the most physical (or physicalist) sense. I proceed to single out conditional probability as one of the central problematic concepts in this regard and discuss its status. This concept is most often used and introduced in so called subjective probability theories. In frequentist probability its role is to denote non-homogenous subpopulations, which is a concept that physical models generally try to avoid. This approach may present part of the problem in interpretations of quantum mechanics. I end with an evaluation of the concept of physical probability and argue for the need for a broader understanding of probability in physics.