Introduction to Agreement on Demand: Consumer Theory in the Twentieth Century Philip Mirowski and D. Wade Hands The purpose of demand theory is to explain consumer market behavior. —Donald Katzner, Static Demand Theory (1970) The theory of demand, or consumer choice theory, is prominently featured in the early chapters of every microeconomics textbook—introductory, intermediate, or graduate—and has appeared in essentially the same place and in the same basic form for over a half-century. The theory’s basic idea is quite simple, or at least seems to be so once the catechism has been learned. It goes like this. The theory begins with the assumption that demand curves relating the amount of a particular commodity that a consumer is willing and able to purchase at various prices exist as phenomenal regularities in market economies. These regularities, it is argued, could be empirically observed by asking the individual how much he (or she) would be will- ing and able to purchase at various prices and/or by simply observing his actual consumption behavior. In either case it is assumed that the func- tional relationship q i = D( p i ) between the price ( p i ) and quantity (q i ) of good i exists and can be empirically estimated. Since the market demand curve is simply the sum of all of the individual demand curves for all the consumers in the market, these market demand curves are similarly assumed to exist as phenomenal regularities. Demand theory is simply an explanation—ostensibly a scientifc explanation—of what is “behind,” History of Political Economy 38 (annual suppl.) DOI 10.1215/00182702-2005-014 Copyright 2006 by Duke University Press Downloaded from https://read.dukeupress.edu/hope/article-pdf/38/Suppl_1/1/428463/HOPE385-01mirowintro.pdf by guest on 12 June 2020