Consumer surplus in the Edgeworth box: Individual case and general case

Abstract

Subject. The article considers weakly cardinal properties of the generalized individual consumer surplus on the simple exchange economy (Edgeworth box) case. Objectives. The aim is to find the new weakly cardinal properties of individual consumer surplus in the Edgeworth box economy in the quasilinear case and in the general case. Methods. The study draws on methods of logical and mathematical analysis. The generalized consumer surplus theory is investigated using the mathematical theory of the curve integrals of the second type. Results. Individual surplus generates money metric utility function with unitary marginal utility of numeraire in the Edgeworth box. The paper gives the definition of consumer surplus’ path-independence property, proves the theorem that path-independent consumer surplus is equivalent to the existence of consumer’s quasilinear preferences in a simple exchange economy, presents the characterization of general case of consumer surplus in the Edgeworth box, and provides general taxonomy of trejectories (adjustment paths) in the Edgewoth box. Conclusions. The generalized individual consumer surplus generates money metric utility function along monotone (weakly monotone) trajectories in the Edgeworth box. If consumer is a buyer of the first good, I again demonstrate that consumer surplus is presented as an area between the reservation price function and the reallocation line (curve).