Journal Article The Dun-Gibson Index Number Get access Wesley C. Mitchell Wesley C. Mitchell University of California Search for other works by this author on: Oxford Academic Google Scholar The Quarterly Journal of Economics, Volume 25, Issue 1, November 1910, Pages 161–172, https://doi.org/10.2307/1885829 Published: 01 November 1910

reasonable being who always intelligently seeks his own good or is guided in all his activities by enlightened self-interest." The truth is, Mr. McDougall asserts that "mankind is only a little bit reasonable and to a great extent very unintelligently moved in quite unreasonable ways."32 That is, the economists have committed "the intellectualist fallacy." In considering whether this criticism is just with reference to contemporary economics, it is necessary to summarize the psy? chological assumptions commonly made. The statement which follows is intended to apply primarily to economic theory of the eclectic type. An element of psychological unreality is clearly present in most expositions of the theory of value. Bargainers are usually represented as exchanging two consumption goods?say nuts and apples. They come to market with definitely formulated ideas of how many units of the good in their possession they will give to get each successive unit of the other good. These demand schedules rest upon equally definite ideas concerning the varying marginal utilities which each good has for them as the supply is increased or diminished. The artificiality of the whole picture is further enhanced by using diagrams to show the vary? ing marginal utilities of goods, and the varying disutility of successive hours of labor.