Intensional vs extensional probabilities from their origins to Laplace / U. Garibaldi and M.A. Penco.
Abstract:
'This paper compares one of the first applications of probability calculus to human testimony, a treatise which appeared in 1699 in the "Philosophical Transactions", [an anonymous paper, 'A calculation of the credibility of human testimony',] with Laplace's treatise of 1814 on the same subject, in order to emphasize the radical conceptual changes which occurred in the field of probability during the late 18th century.'
Historia mathematica Vol. 18 (1991), p. 16-35