 First, the Bayes-Laplace argument relies on the rules of the probability calculus. What is the status of these rules? Does following them amount to a priori reasoning? The answer to this depends in part on how probability itself is interpreted. Broadly speaking, there are prominent interpretations of probability according to which the rules plausibly have a priori status and could form the basis of a demonstrative argument. These include the classical interpretation originally developed by Laplace (1814), the logical interpretation (Keynes (1921), Johnson (1921), Jeffreys (1939), Carnap (1950), Cox (1946, 1961), and the subjectivist interpretation of Ramsey (1926), Savage (1954), and de Finetti (1964). Attempts to argue for a probabilistic a priori solution to the problem of induction have been primarily associated with these interpretations.