SEX DISCRIMINATION IN WAGES 157 The three sub-diagrams represent three categories of occupations as classified by Edgeworth. In male occupation only males are employed because Dp, the demand curve for female labour falls below W the wage rate; in female occupation it is the other way round and in the mixed occupation Dp and DM merge into one DL, there being no difference in male and female productivity. Note ttiat the supply of labour is represented by SL which indicates perfect elasticity of total labour, that is, supply of male and female labour taken together. The sorting takes place between male and female labour from the demand side. If at wage W no female worker is employed it is because at that wage the value of their marginal product is less than W and not because women are not forthcoming; the same can be said for the absence of male employment in the female occupation. It is in the mixed occupation where on grounds of productivity there is little to choose between male and female labour that the question arises as to the proportion in which they will be combined. But this should be no different from the proportions in which they combine in the labour force.* In fact it appears that under competitive conditions wage discrimination is not possible on the basis of differences in productivity even if one made the sort of assumption deriving from Plato's view that women are less efficient than men in all jobs though the disparity is not the same in all the jobs. . Inferiority Coeffiicient The latest theory from Chicago to explain wage discrimination against black workers seems to do precisely this in that given the taste for discrimination on the part of the white discriminate rs, a black worker is considered inferior and the evaluation of this inferiority can be expressed in terms of the lower wage offered to him. Thus if the white worker is paid Ww in a particular job, the black worker in the same job is offered onlyWw(l-d), where d is the inferiority or discrimination coefficient.7 However as we shall see in thp following paragraph even the existence of this taste for discrimination need not result in actual wage discrimination. The existence of this discrimination is assumed to be universal so that there is no .talk then of some occupations where the black man is DIAGRAM II Of M T Volume of EmpleymcMt