Augustin Courtnot and neoclassical economics

This paper compares Courtnot's exposition of elasticity of demand and the theory of the firm with modern exposition. In the case of the theory of the firm, this comparison is accomplished by translating the modern textbook exposition into Cournot's mathematics. It is demonstrated that Cournot's exposition translates into current usage in all cases but that the degree of convolution in the translation process varies from case to case. For elasticity, only trivial algebraic manipulation is involved. For monopoly, the inverse derivative rule translates Cournot's exposition into current usage. The case of perfect competition is much more complicated. Although Cournot gets the same result as current theory, his mathematics doesn't translate directly into current usage. But a comparison in the text that doesn't appear in his mathematics suggests that he considered the modern derivation but chose to use another derivation. One reason for doing this is rather obvious. It fits better into Cournot's unified approach to the theory of the firm. It might also be judged more elegant and mathematically precise. With regard to oligopoly, Cournot provided, in a different contest, the analytical structure that is now used in 10 to analyze differentiated oligopoly. It is reiterated that Cournot had a general method for finding equilibria for non-cooperative games and was aware of the fact that his method was more general than a single application. The relation between Cournot equilibria and Nash equilibria is discussed. (JEL B13, B21)