 Applying Popper’s views on falsification literally would be destructive. Not only neoclassical economics, but all significant economic theories would be condemned as unscientific, and there would be no way to discriminate among economic theories. One major problem with a naive reading of Popper’s views is that one cannot derive testable implications from theories by themselves. To derive testable implications, one also needs subsidiary assumptions concerning probability distributions, measurement devices, proxies for unmeasured variables, the absence of interferences, and so forth. This is the so-called “Duhem-Quine problem” (Duhem 1906, Quine 1953, Cross 1982). These problems arise generally, and Popper proposes that they be solved by a methodological decision to regard a failure of the deduced testable implication to be a failure of the theory. But in economics the subsidiary assumptions are dubious and in many cases known to be false. Making the methodological decision that Popper requires is unreasonable and would lead one to reject all economic theories.