Economic theory is, then, both much more and much less than an instruction sheet. It is more because it is causally important in the world, and not just a correspondent reflection of it—it is, in the language of economics, endogenous to it. Different theories tell us which rules to pick, which policies to follow, and how to design institutions, providing different payoffs to different groups, in the process changing the world that the theories purport to map. But economic theory is also much less than an instruction sheet because of the partial nature of various theories and how incompletely they map onto the world they strive to describe.

Mark Blyth, Austerity, loc. 122