Population and Development: A More General Model

Abstract

Two recent notes in this journal illustrate the continuing interest in the problem of overpopulation.1 Cole's comment stresses the importance of distinguishing static and dynamic concepts of overpopulation. Much of the confusion between the two concepts could be reduced by studying a simple model of optimum population growth. This model has been constructed by Goran Ohlin.2 I feel Ohlin's model should receive more attention than it has to date. In this paper I will attempt to explain the importance of Ohlin's innovation and to illustrate the ease with which it can be generalized to include potentially relevant policy considerations. This paper is divided into four sections. In the first section Ohlin's model will be compared with the earlier models of economic and population growth formulated by Richard Nelson3 and Stephen Enke.4 In this presentation Ohlin's model is slightly modified from its original form. In the original model infinitesimally small changes were studied. In this version all changes are discrete. This alteration is necessary because policy makers may find it difficult to conceive of, much less manipulate, instantaneous growth rates. A further modification will be made in the second section. If the model is to be used to determine the optimal growth of population, the costs of altering population growth must be taken into consideration. The costs of various population policies are incorporated in the second section.