Assessments of J. M.Keynes’s a Treatise on Probability (1921), Made by All Academic Philosophers and Economists Since 1921, Rely on pp.30–34 of Chapter III, pp.71–78 of Chapter VI (Page 312 of Chapter XXVI) Plus Some Pages Taken From Chapter IV On the Principle of Indifference : No Current Academic Philosopher or Economist Has Any Specific Understanding About What Keynes Did in Part II (Parts III ...

The unanimous conclusion of philosophers and economists over the last 100 years is that Keynes‘s contribution to a theory of imprecise probability in his A Treatise on Probability was to provide some interesting notions, intuitions, ideas, suggestions, hints, or clues about imprecise probability, but that Keynes himself had never provided any worked out theory using mathematical and logical analysis. Henry E. Kyburg,Jr., over a period of 53 years from 1959 to 2011 (he died in 2007), argued that Keynes's contribution came only from pp. 30-34 of chapter III of the A Treatise on Probability. This contribution was to suggest the idea of a partial order and the fact that not all probabilities were comparable, measurable or commensurable quantitatively. Economists (for example ,D.Moggridge,R.Skidelsky, A.Carabelli,R.O'Donnell,J.Runde) concluded that Keynes had constructed an ordinal theory of comparative probability based on pp. 38-40 of chapter III of the A Treatise on Probability. There is a clear conflict here between the philosophers and economists, with the philosophers believing that pp. 30-34, if developed, would lead to an interval valued theory of probability while the economists, based on pp. 38-40, believing that Keynes was suggesting an ordinal theory of comparative probability.The first philosopher to accept the economist position was S. Bradley in 2019 in a paper published in the Stanford Encyclopedia of Philosophy. Bradley accepted the economist claim that Keynes's theory was an ordinal theory based on the diagram on p.39 of chapter III of the A Treatise on Probability.Both positions have very serious defects in them, although the economists‘ position has the more severe deficiencies.This author believes that it would have been a relatively simple matter, at any time during the last 100 years, for philosophers and/or economists to have actually read Part II of Keynes's A Treatise on Probability. They then would have discovered that Keynes had provided a complete, technically advanced, mathematically and logically developed theory of imprecise probability, using upper and lower probabilities, i.e. intervals. Keynes's description, that such intervals are non (not) numerical probabilities, should have been obvious