Janina Hosiasson and the value of evidence

Abstract

I.J. Good’s “On the Principle of Total Evidence” (1967) looms large in decision theory and Bayesian epistemology. Good proves that in Savage’s (1954) decision theory, a coherent agent always prefers to collect, rather than ignore, free evidence. It is now well known that Good’s result was prefigured in an unpublished note by Frank Ramsey (Skyrms 2006). The present paper highlights another early forerunner to Good’s argument, appearing in Janina Hosiasson’s “Why do We Prefer Probabilities Relative to Many Data?” (1931), that has been neglected in the literature. Section 1 reviews Good’s argument and the problem it was meant to resolve; call this the value of evidence problem. Section 2 offers a brief history of the value of evidence problem and provides biographical background to contextualize Hosiasson’s contribution. Section 3 explicates the central argument of Hosiasson’s paper and considers its relationship to Good’s (1967).