Retrospectives: Lionel W. McKenzie and the Proof of the Existence of a Competitive Equilibrium.

The theorem proving the existence of general equilibrium in a competitive economy, which necessarily involved specifying the conditions under which such an equilibrium would exist, is an extraordinary achievement of twentieth-century economics. The discovery is commonly attributed to a paper by (eventual) Nobel Prize winners Kenneth Arrow and Gerard Debreau: ''Existence of an Equilibrium for a Competitive Economy,'' published in the July 1954 issue of Econometrica. However it is less well-known that Lionel McKenzie published a paper in the previous issue of Econometrica, ''On Equilibrium in Graham's Model of World Trade and Other Competitive Systems,'' that discussed many of the same themes. Both papers established the existence of a competitive equilibrium for suitable general equilibrium models and employed fixed point theorem arguments. McKenzie had priority in publication in 1954 and received credit for simultaneous discovery in prominent sources around that time. But over the years, McKenzie's role in creating the proof of the existence of a general equilibrium seems to have faded from the collective consciousness of the economics profession. Newly available archival material permits a reexamination of the events surrounding the publication of both Econometrica papers in 1954. The story raises general issues concerning ''simultaneous discovery,'' ''priority,'' and ''credit'' in economic research and opens a window into some academic practices of that time. [ABSTRACT FROM AUTHOR]