ABSTRACT
The Treatise on Probability, as expanded from the dissertation, would limit the value of probability in the sense of frequency to subordinate it to probability as belief, this latter a question of the credibility of propositions and situated by Keynes in the field of logic. The reviews of the Treatise on Probability were well mixed. O'Donnell has reprinted excerpts of eight "favorable," six "unfavorable," and three "others." Probability-as-belief was one of the two major strands of the treatise's argument. The other was Keynes's thesis of probability-as-frequency as a special case of belief. Speaking loosely, given the ambiguities, the difference is overwhelming—some ten or twenty times as much sheer wordage expended on probability-as-frequency as on probability-as-belief. The pairing of probability-and-belief and probability-as-frequency is the most important expression of Keynes's failure in epistemology. This was pointed out by Frank Ramsey, a brilliant young don who was a mathematician and philosopher—and a young friend of Keynes.
