@techreport{oai:shiga-u.repo.nii.ac.jp:00009907, author = {酒井, 泰弘}, issue = {No. J-36}, month = {Apr}, note = {Technical Report, The main purpose of this paper is to critically discuss and lucidly compare J. M. Keynes (1883-1946) and F. H. Knight (1886-1972), two towering figures in the history of economic thought. It is in 1921 that they both published apparently similar books on risk, probability and uncertainty. While Knight’contribution on the economics of risk and uncertainty has been well-known and very influential in the economics profession, Keynes’ accomplishments on probability and uncertainty have been more or less underestimated in the dark shadow of his most famous book (1936 ) The General Theory of Unemployment, Interest and Money. The present paper aims to focus on an earlier yet equally important book (1921) A Treatise on Probability, hopefully shedding a new light on his outstanding ideas and everlasting influences on his later works including The General Theory. According to Keynes, many probabilities, which are incapable of numerical measurement, can be placed nevertheless between numerical upper and lower limits. Keynes has demonstrated whether and to what extent animal spirits contributes to the working and performance of the market economy. Remarkably, Keynes' concept of probability and uncertainty can be well-compared to Knight's distinction between a measurable risk and a non-measurable uncertainty. I believe that it is high time for us to unify Keynes and Knight into a new, comprehensive approach to understanding complex human behavior., CRR Discussion Paper, Series J, No. J-36, pp. 1-22}, title = {ケインズとナイト : 蓋然性と不確実性を中心として}, year = {2013} }