By the time that Keynes’s logical theory of probability appeared in 1921 in his A Treatise on Probability (1921), Keynes had already used it in his Indian Currency and Finance,1913, personally at the Treaty of Versailles negotiations as the official representative of the British Treasury Department, and in his Economic Consequences of the Peace (1919). Keynes was a millionaire by 1922. Keynes’s theory is an interval valued approach that can be applied in situations that require imprecise, inexact, non numerical, nonlinear, non additive, degree of rational belief. If the weight of the argument, w, is equal to, approaches, or is close to 1, 0≤w≤1, then Keynes’s theory reduces to the use of precise, exact, numerical, linear, additive, degrees of belief. This conclusion can only be reached if an academic has read and understood Part II of the A Treatise on Probability. The only academic in the 20th or 21st century who read Part II of the A Treatise on Probability was Theodore Hailperin, a mathematician who had no idea about the strange and queer literature that has built up around this book in academia since 1921.One of the many queer and strange episodes that have been written about Keynes’s theory over the last 100 years is the claim that in 1931 Keynes agreed to abandon his logical theory of probability because an 18 year old boy convinced Keynes that his theory had major logical, epistemological, and philosophical problems, such as mysterious and mystical non numerical probabilities, as well as bizarre claims by Keynes that the intuition and perception of the individual decision maker played an important role in allowing the decision maker to grasp an understanding of the fundamental nature of the current problem under investigation, as it related to past successful analyses of similar problems.Of course, it is in Parts II and III of the A treatise on Probability that Keynes demonstrates what his technical, mathematical apparatus is for dealing with problems of decision making concerning the future where only partial information, knowledge, evidence or data is available, but that is in many instances in conflict.Keynes was impressed with Ramsey’s ability to grasp and talk with him about issues related to decision making. Unfortunately, Ramsey had NO experience at all in the real world of decision making subject to time constraint, a world that Keynes had used his theory between 1912 and 1919 to master. Ramsey’s theory was a purely academic theory that required a complete information set, exactly what Keynes had shown was rarely the case. The belief, resurrected recently in 2020 by Cheryl Misak in her biography of Frank Ramsey, that Keynes’s confidence in his theory was severely shaken, simply has no support for it .Did any academic economist or philosopher ever read Part II of the TP? I can find no evidence to support the hypothesis that there was an academic economist or philosopher who read Part II of the TP in the last 100 years. Such an economist or philosopher would have immediately objected to the 100 year old Ramsey myth that Keynes’s mysterious and/or mystical non numerical probabilities and non measurable probabilities were not really mysterious at al .Such an economist or philosopher would have immediately pointed out that Keynes’s "platonic entities" were intervals with an upper and lower bound, which means that they are non additive and do not satisfy the mathematical laws of the calculus of probabilities. Unfortunately, no such academic economist or philosopher exists, as a check of Google Scholar will make clear
