Sidgwick and Edgeworth on indeterminacy in the labour market

Commentators have underlined Sidgwick's influence on Edgeworth's thinking and more particularly on New and Old Methods of Ethics (1877). But have failed to notice that Sidgwick remained a major reference in Mathematical Psychics (1881). Therefore, the purpose of this paper is to show that, in this book, Edgeworth wanted to refine upon the problem of wages addressed by Sidgwick in 1879. The thesis of the paper is that Sidgwick and Edgeworth's disagreement as to the role of open competition in the resolution of indeterminacy in the labour market stems from two different notions of competition. This latter can be seen as a differentiation process, as in Sidgwick's, or as a replication mechanism, as in Edgeworth's.