ON THE SIGNIFICANCE OF CONDITIONAL PROBABILITIES

The orthodoxy that conditional probabilities reflect what are for a su bject evidential bearings is seconded. This significance suggests that there should be principles equating rationally revised probabilities on new information with probabilities reached by conditionalizing on t his information. Several principles, two of which are endorsed, are co nsidered. A 'book' is made against a violator of these, and it is argu ed that there must be something wrong with a person against whom such books can be made. Appendices comment on Popper-functions, elaborate o n bets and odds, and relate dutch books and strategies to conditions o f inconsistency (Ramsey's idea) and imperfection.