 The real problem with ABD1 runs deeper than this, however. Because abduction is ampliative—as explained earlier—it will not be a sound rule of inference in the strict logical sense, however abduction is explicated exactly. It can still be reliable in that it mostly leads to a true conclusion whenever the premises are true. An obvious necessary condition for ABD1 to be reliable in this sense is that, mostly, when it is true that H best explains E, and E is true, then H is true as well (or H is approximately true, or probably true, or probably approximately true). But this would not be enough for ABD1 to be reliable. For ABD1 takes as its premise only that some hypothesis is the best explanation of the evidence as compared to other hypotheses in a given set. Thus, if the rule is to be reliable, it must hold that, at least typically, the best explanation relative to the set of hypotheses that we consider would also come out as being best in comparison with any other hypotheses that we might have conceived (but for lack of time or ingenuity, or for some other reason, did not conceive). In other words, it must hold that at least typically the absolutely best explanation of the evidence is to be found among the candidate explanations we have come up with, for else ABD1 may well lead us to believe “the best of a bad lot” (van Fraassen 1989, 143).