One Hundred Years After Keynes’s a Treatise on Probability Appeared, There Is Still Pervasive Confusion Among Academics About the Logical Theory of Probability: Keynes’s Theory of Logical Probability Is an Interval Valued Theory of Probability Based On Boole That the 18 Year Old Ramsey Never Understood in His Life

Abstract

The very recent publication of C. Misak’s autobiography of F P Ramsey in 2020, as well as a number of book reviews made by different reviewers of that book, have resulted in the resurrection of highly misleading claims made by F. Ramsey, when he was 18 years old, that can only be characterized as being silly -to someone who has actually read the entire book. Therefore, individuals, who have only read Part I of Keynes’s book, are highly susceptible to claims made when reading book reviews of academics who never read the book they claimed to be reviewing. Such is the case with Frank Ramsey. The Keynes -Townshend correspondence in 1937 – 1938 over the connections between the A Treatise on Probability and the General Theory, as well as the Keynes-Tinbergen exchanges of 1938-1940 concerning Keynes’s critique or Tinbergen’s use of precise probability and the Normal distribution to model the business cycle, make it crystal clear that Keynes never accepted Ramsey’s critique in his lifetime and continued to use his own logical theory of imprecise probability .Ramsey’s subjective theory of probability is a theory of precise probability that can’t deal with overlapping evidence or conflicting evidence. Of course, Keynes did believe that Ramsey had strengthened the logical foundations for PRECISE probability with his betting quotient approach combined with his Dutch book argument regarding degrees of belief. However, Keynes’s logical theory is one that is based on rational degrees of belief and imprecise probability. Only in a very special case, where Keynes’s degree of the completeness of the relevant evidence, w, equaled 1 on the unit interval would Keynes have considered using Ramsey’s theory. A similar fate has occurred regarding Keynes’s separate theory of the Evidential Weight of the Argument. Here we will find a plethora of mathematical and logical errors littering the academic journals in economics and philosophy.