Equidynamics and reliable reasoning about frequencies

Abstract

Strevens’ Tychomancy is an important book for philosophers and historians of science, and for scientists interested in the processes by which we reason about probabilities and frequencies, or interested in the evolution of our ability to do so. Strevens notes that we often have very good intuitions about probability and frequencies in physical processes, and asks how and why that is so. He describes several closely related reasoning strategies that would justify such intuitions. These “equidynamic” (xi) reasoning strategies1 can be used to infer, beginning from relatively minimal assumptions, conclusions about frequencies of outcomes of physical processes involving complex interactions. Strevens illustrates the strategies by applying them to examples such as Maxwell’s derivation of an equilibrium probability distribution over states of a gas, physical games of chance and similar systems, and organisms interacting in evolving populations. Strevens argues that we routinely engage in these reasoning strategies, largely through unconscious processes that are in some sense innate.