How Academicians Fell for Ramsey’s Canard that Keynes did not Give a Definition of Probability

Abstract

It was F P Ramsey who first claimed that Keynes had stated that probability was indefinable in his 1922 review of Keynes’s A Treatise on Probability in the January issue of Cambridge Magazine: “Mr Keynes takes probabilities or probability relations as indefinable, and says that if q has to p the probability relation of degree a, then knowledge of p justifies rational belief of degree a.” (Ramsey,1922, p.3). Ramsey made an intellectual mess that made it impossible for a reader to understand what Keynes’s formal relational, propositional logic was. This mess can be fixed to some degree by rewriting it in the following manner-Mr. Keynes takes probability as being indefinable if a single definition is required to be given. Let p and q be related propositions, where p contains the premise(s) and q is a conclusion(s) of an argument form based on p. Then knowledge of p justifies a rational degree of partial belief of a in q.