Discrimination against members of a group might be based on aversion to the group, which might exist quite independently of the actual characteristics of actual group members. For example, an employer might simply dislike Catholics or Jews or women, and be averse to hiring them, or to hiring them for other than unskilled low-paid jobs. One might suppose that if one has a taste for discrimination of this sort, one must incur costs if one acts on it (Becker 1971). If one refuses to hire Catholics or Jews or women even when they are most qualified, the product one offers for sale will be more costly to produce as a result, and if the market for this product is competitive, one cannot raise the price at which one sells it but must accept lesser profit than one would have obtained had one's hiring decisions been unprejudiced.  On this basis one might speculate that competitive markets will tend to drive out such discrimination. However, if large numbers of people share a discriminatory social norm, one can see that the market will reward compliance with the norm and punish noncompliance, so there will in that case be no tendency for the market to squeeze out discriminatory behavior. For example, if consumers will not purchase widgets that are manufactured with the skilled labor of Catholics, Jews, or women, and if skilled Protestant male workers employed in the widget industry will not cooperate with Catholics, Jews, or women if they are hired as skilled co-workers, the widget manufacturer who simply wishes to maximize her profits will be led to comply with the social norm against the employment of the targeted groups in skilled jobs (Akerlof 1976, 1980).