 Popper offered two explications of why ad hoc hypotheses were suspect. One was that if we offer T as an explanation of f, but then cite f as the only reason we have to believe T, Popper claims that we have engaged in reasoning that is suspicious for reasons of circularity (Popper 1972: 192–3). This was arguably fallacious on Popper’s part—a circular proof would offer one proposition, p, in support of a second proposition q, when q has already been offered in support of p. But in the above example, while f is offered as evidence for T, T is offered as an explanation of (not as evidence for) f—and thus there is no circular reasoning (Bamford 1993: 338). 