The user of a theory has a simpler task: his not to reason why, his but to sigh and try. If the right element in the diverse situations has been isol… - George Stigler

Economic theories are infinitely diverse in their predictive power. Entirely too many have zero predictive power-they are statements of tautologies. Thus the statement that to maximize profits one should operate a firm where marginal revenue equals marginal cost is a mere mathematical statement of the condition for a maximum. The example we gave of search theory is not a tautology because we can identify the factors that influence costs and returns.· Some theories have negative power: they predict the opposite of what happens (and then become useful in the hands of a sophisticated user).

Consider the Negro as a neighbor. He is frequently repelled and avoided by the white man, but is it only color prejudice? On the contrary, it is because the Negro family is, on average, a loose, morally lax group, and brings with its presence a rapid rise in crime and vandalism. No statutes, no sermons, no demonstrations, will obtain for the Negro the liking and respect that sober virtues commend. And the leaders of Negro thought: they blame the crime and immorality upon the slums and the low income—as if individual responsibility could be bought with a thousand dollars a year.

In the 1950s, I proposed the survivor method of determining the efficient sizes of enterprises, and worked on delivered price systems, vertical integration, and similar topics.