 A common argument for predictivism is that we should avoid inferring that a theory T is true on the basis of evidence E that it is built to fit because we can explain why T entails E by simply noting how T was built—but if T was not built to fit E then only the truth of T can explain the fact that T fits E. Various philosophers have noted that this reasoning is fallacious. As noted above it makes no sense to offer an explanation (for example, in terms of how the theory was built) for the fact that T entails E—for this latter fact is a logical fact for which no causal explanation can be given. Insofar as there is an explanandum in need of an explanans here it is rather the fact that the theorist managed to construct or ‘choose’ a theory (which turned out to be T) that correctly entailed E (Collins 1994; Barnes 2002)—that explanandum could be explained by noting that the theorist built a theory (which turned out to be T) to fit E, or endorsed it because it fit E. 