Around here," the prominent finance theorist Merton Miller told me, "we just sort of take [Friedman's viewpoint] for granted. Of course you don't worry about the assumptions." (Miller interview) By "here" Miller meant the University of Chicago, but he could as easily have been describing much of finance theory. Attitudes to the verisimilitude of assumptions did differ, with Samuelson and (to a lesser extent) his student Robert C. Merton distancing themselves somewhat from the more Friedmanesque attitudes of some of their colleagues. However, that a model's assumptions were "unrealistic" did not generally count, in the epistemic culture of financial economics, as a valid argument against the model.

Donald MacKenzie, An Engine, Not a Camera, loc. 63