Because of the complexities of econometric testing, the extent of the "fit" between a theoretical model and patterns of prices cannot be determined by simple inspection. "There just isn't any easy way to test a theory," said Fischer Black (1982, p. 32). Knowledge of whether patterns of prices have moved toward greater conformity with a theory is the outcome of a difficult, and often a contested, process. It is therefore tempting to set the issue aside, and to abandon the strongest meanings of performativity (Barnesian performativity and counterperformativity). However, to do that would involve also abandoning a central question: Has finance theory helped to create the world it posited for example, a world that has been altered to conform better to the theory's initially unrealistic assumptions?

Donald MacKenzie, An Engine, Not a Camera, loc. 114