Chance and Degrees of Belief

Abstract

Are there chances, and if so, what are they? These are still contentious questions. Like Salmon, I believe that there are chances, but I disagree with him about what they are. We do agree on some points, principally that chance is a species of objective probability, namely physical or statistical probability. Some thinkers have claimed to discern another species in this genus, namely the relational probability that inductive logic treats of. I doubt the claim: inductive probabilities are, I suspect, all descended from chances. Certainly most are, so chance is anyway the right species to study first. Whether it exhausts the genus is a question we can afford to leave open.

This paper is my reply to Salmon’s discussion review [1979f] of The Matter of Chance and other propensity theories. Although we still do not agree, I owe much to Salmon’s scrupulous critique, which I try here to answer constructively. My thinking on these topics has also been especially stimulated recently by the work of Blackburn [1980], Jeffrey [1980], Kyburg [1978], Levi [1977], Lewis [1979] and Skyrms [1980]. I thought it would be clearer for me to develop my own ideas here without much cross-reference to points of agreement and difference with others; but my debt to these works should be acknowledged. So should my debt to the Radcliffe Trust, for awarding me a Radcliffe Fellowship, during my tenure of which this work has been done.