IMPERSONAL PROBABILITY AS AN IDEAL ASSESSMENT BASED ON ACCESSIBLE EVIDENCE - A VIABLE CONSTRUCT

When risk analysis and others refer to the ''true'' probability of an event, it is not easy to give it a meaning which is sound and useful as a communication device for regulatory, research planning, and related purposes. An interpretation is herein offered which, unlike Bayesian probability, is impersonal and does not depend on a particular assessor; unlike Carnap's ''logical'' probability, it does not depend on information actually;y to hand. It is a generalization of frequency and propensity interpretations of impersonal probability applicable to unique events: an ideal assessment based on currently accessible (not in general ''perfect'') evidence. The argument is illustrated from decision-aiding experience which motivated the enquiry.