To better understand the dilemmas that adherence to Moore's doctrines imposed on Keynes's early philosophical thinking, it will be helpful to first examine the effects that Moore's Principia Ethica had on thinking in ethics and economics among professional moral philosophers and economists in the several decades succeeding its publication. Moore's influence was clear and significant in the subsequent development of modern moral philosophy in that the emotivist ethical views that shortly supplanted Moore's Principia approach typically made a critique of the book their starting point. In contrast, the effect of Moore's thinking in economics was indirect and subtle, since the methodological thinking that was to have a lasting influence on the economics of price theory, namely, Lionel Robbins's views in An Essay on the Nature and Significance of Economic Science (1935), drew implicitly upon these same emotivist ideas advanced in critique of Moore in their popular formulation. The points of convergence between these two different lines of intellectual development have been little explored. Even less well appreciated is Moore's original role in this history, especially in light of the fact that while Moore had meant to provide objectivist foundations for ethics, it was rather the subjectivist, or, as the emotivists had it, non-cognitivist critique of Moore's thinking that counted as the lasting if unintended influence of his work in both ethics and economics.