Ramsey's Biconceptual Probability versus de Finetti's Radical Probabilism

Abstract

The decline of the 'doctrine of the association of ideas' in the 19th century resulted in the deepening of the differences between the subjectivist and objectivist interpretations of probability until they became incompatible. The formalisation of this controversy materialised with the emergence of the concept of 'personal probability' by Ramsey and de Finetti, who, while agreeing on the need for a 'logic of the probable', put forward different proposals: Ramsey's proposal was founded on a thorough critique of the Keynesian interpretation, while de Finetti's approach adopted a clearly anti-frequentist character. A detailed analysis of this controversy led to the conclusion that de Finetti's increasingly dogmatic position deepened this conceptual divorce and led Ramsey to the objective definition of 'chance' and in a return to the theory of the association of ideas, to adopt a “biconceptual” vision, which postulates two combined interpretations of probability, one based on the theory of propensities and another, subjectivist, understood as a degree of belief.