A-realistic assumptions

Tons of mischief would have been saved in the epistemology of economics had Friedman referred to the a-realism of the assumptions rather than to its unrealism. Friedman's whole point is easily understood and made compatible with, say, praxeological epistemology if you realize that the role of assumptions is to describe only the relevant elements of reality, therefore remaining necessarily silent to the rest of the description of reality. Assumptions can't be fully descriptive. That's the essence of Friedman's. But this feature refers to a lack of conveying information, not to the conveying of false information.

When the assumption of "perfect information" is given, this is just an economic way of saying that no attempt of analysis will be made with the theory to explain the imperfection of information. The assumption is a clause of resignation. Yes, a very coarse, superficial, and ultimately wrong exegesis would state that perfect information is an unrealistic assumption because information isn't really perfect, but the true role of the assumptions is rather a-realistic: to give up the possibility of analyzing the role of the imperfection of information, to abstract the phenomenon to study from informational rough edges, to specialize the theory in certain other problems not related to information. But, what's of the most importance regarding Friedman's conclusions: this resignation is content-meaningful. It's not just irrelevant whether it's a-realistic or not: it is precisely the way in which the very boundaries of the explanatory power of the theory is defined, it alone tells us what for and what not for is the theory! You have to pay close attention to the propositions stated through assumptions because they tell you when can you use the theory. Maybe if we understand this, we can be not so harsh as Hayek when he bitterly criticizes the whole equilibrium analysis (see his "The Use of Knowledge in Society") or when Kirzner does the analogous with the model of perfect competition (in "Competition & Entrepreneurship)".

I think that the true contribution of Friedman can be stated as "the violation of the assumptions of a theory have no appreciable effect on the implications of such a theory". (Compare to page 18 in the original edition of the essay.)

Additionally, even if more implicitly and less frequently quoted, I think that an important contribution of Friedman's essay is the fact that every theory is a construction, a designed, and in this sense, artificial, explanation of reality; that there is no such a thing as a "real" or utopically true explanation beyond the theory.