The auther is correct that the most important concept developed by Keynes was the connection between uncertainty and expectations of future change about technology,innovation,obsolesence of present fixed capital,etc., and the connection of uncertainty and expectations to long lived capital investment ,financial markets, speculative behavior,and the existence of involuntary unemployment.Unfortunately,the author simply lacks the knowledge of the technical breakthroughs made by Keynes in his A Treatise on Probability in chapters 15,16,17,20,22,26, and 29(TP;1921.See also the same practically identical material that appeared much earlier in Keynes's 1908 Cambridge Fellowship Thesis). Jespersen completely overlooks the way that Keynes reformulated his TP analysis in chapter 21 of the GT to show how to integrate his analysis of the conventional coefficient of risk and weight,c, into an elasticity analysis that presented a completely worked out generalization of the neoclassical equation of exchange on pp.304-306 of the General Theory. Neoclassical economics is proven mathematically by Keynes to require that the elasticies e,ep subscript,and ed subscript must always equal 1.Neoclassical economics is based on the mathematical laws of the probability calculus which require linear and additive functions. Only in the special case where there is no uncertainty and only risk will this occur.Keynes's argument,without the discussion of the technical elasticity conditions in chapter 21 of the GT ,was laid out very clearly in written English on pp.208-209 in section 4 of chapter 15 of the GT.All of this is skipped by Jespersen.The exact same argument was presented by Keynes in chapter 26 of the TP using a version of his lower-upper interval,non additive,non linear approach to probability .Keynes called this particular form of his general analysis his conventional coefficient of risk and weight,c.Keynes's analysis is presented for the interested reader below:Keynes presented a clearcut mathematical,technical analysis of ambiguity aversion using his conventional coefficient of risk and and weight( uncertainty),c,in chapter 26 of the TP. A very specific example of Keynes's nomlinear and non additive approach to probability in chapters 15,17,20,and 22 of the TP was worked out in great detail by Keynes in chapter 26 using his conventional coefficient of risk and weight ,c,formulation on p.315 and in Footnote 2 on p.315.Edgeworth, in his 1922 article on " The Philosophy of Chance " in Mind ,was certainly correct in asking for the help of the readers of that philosophy journal in order to figure out the what and the why's involved in the application of Keynes's c coefficient.Unfortunately it was never done in Mind or anywhere else . See my SSRN paper with Gorga that is currently in press at an economics journal.The foundation of Neoclassical economics is merely the mathematical development of a theoretical approach first proposed by Jeremy Bentham in 1787 in direct opposition to Adam Smith's 1776 Wealth of Nations aproach.Bentham claimed that all individuals have the capability to calculate the odds and outcomes and act on the expected value (the probability times the outcome) in a rational way.This can be expressed by the following ,where p is the probability of success and A is the outcome:Maximize pA.The modern version of this is to Maximize pU(A),where p is a subjective probability that is additive,linear,precise,and exact.U(A) is a Von Neumann-Morgenstern Utility function.The goal is toMaximize pU(A).The modern name for Benthamite Utilitarianism in neoclassical economics is SEU theory(Subjective Expected Utility).Therefore,a microeconomic foundation based on Utility Maximization is just Benthamite Utilitarianism updated with modern mathematical techniques.Modern macro is all SEU theory.Keynes rejected Benthamite Utilitarianism as a very special case that would only hold under the special assumptions of the subjectivist,Bayesian model-that all probabilities were additive,linear,precise,single number answers that obeyed the mathematical laws of the probabiity calculus.Keynes specifies his conventional coefficient of risk and weight,c, model in chapter 26 of the TP on p.314 and fotnote 2 on p.314,as a counter weight to the Benthamite Utilitarian approach.Essentially, Keynes's generalized model is given byc=2pw/(1+q)(1+w),where w is Keynes's weight of the evidence variable that measures the completeness of the relevant, available evidence upon which the probabilities p and q are calculated.(Benthamite Utilitarians assume that the value of w is always 1.)w is an index defined on the unit interval between 0 and 1,p is the probability of success,and q is the probability of failure.p+q sum to 1 if they are additive.This requires that w=1.Keynes's c coefficient can be rewritten asc=p [1/(1+q)][2w/(1+w)].Now multiply by A or U(A).One obtainscA= p[1/(1+q)][2w/(1+w)]A.The goal is to maximuze cA or cU(A).The weight 1/(1+q) deals with non linearity.The weight 2w/(1+w) deals with non additivity.Modern Macroeconomics amounts to nothing more than the claim that c=p or cA (cU(A)= pA (pU(A)) .It is now straightforward to see that the neoclassical microfoundations of macroeconomics assumes that all probabilities are additive and linear.This is nothing but a special case of Keynes's generalized decision rule to maximize cA,or cU(A),as opposed to the Benthamite Utilitarian ,neoclassical rule to maximize pA or pU(A).It is now clear that Keynes had created general theories of macroeconomics,probability,and decision making between 1921 and 1936 that incorporate neoclassical micro and macro as special cases.No reader of this book will have a clue to what Keynes accomplished.Keynes's accomplishments,once understood,make him the only rival to Einstein for the title of the greatest scientist of the 20th century. Economists have only a very vague,hazy,cloudy understanding of Keynes 's distinction between risk and uncertainty.It is no different in Jespersen's case . It is this distinction that has to be grasped first before any economist has any hope of understanding " what Keynes means" in the GT.The conclusion is very straightforward. SEU theorists use the rule to Maximize pU(A).Keynes used the rule to maximize cU(A).Keynes's rule is of the same kind or type of rule used by the overwhelmingly ambiguity averse decision makers that populate the real world in the past and today in the present.Keynes's analysis of uncertainty is clearly related to non additivity and nonlinearity.It is only an anomaly in a world of linearity and additivity of neoclassical economics that exists for neoclassical SEU theorists.I can't recommend Jespersen's book for any reader.Keynes's analysis has nothing to do with either Karl Popper or Critical Realism.The student will come away dazed and confused.He will have no idea about what Keynes really meant and actually did accomplish in the GT and TP.