Dispositional Probabilities

Abstract

The propensity interpretation poses an intriguing alternative to the frequency definition for the explication of probability as a physical magnitude. It is intended to provide an explicitly dispositional account of this concept within the context of statistical laws. First systematically advocated by Karl Popper, it has been endorsed — in one form or another — by Ian Hacking and D. H. Mellor, among others. The purpose of this paper is, first, to distinguish two rather different formulations of the propensity construct (which we shall refer to as the ‘long run’ and ‘single case’ concepts); second, to explain away some of the objections that, prima facie, might be thought to undermine an explication of this kind; and, third, to analyze the inadequacies of a single case dispositional account that fails to take seriously the concept of probability as a statistical disposition.

The author would like to take this opportunity to express his appreciation to Ronald N. Giere for drawing his attention to the logical difference discussed in Section I.