Bob Fischer

A potential explanation of a fact is a hypothesis such that, if it were true, it would explain the fact in question. Let’s suppose that we become aware of a fact and some potential explanations thereof. Let’s also suppose that we would like to believe the truth. Given this aim, we can ask two questions. First, is it likely that one of these hypotheses is true? Second, given an affirmative answer to the first question, which one is it likely to be? Inference to the best explanation (IBE) offers answers to both questions. To the first, it says ‘Yes’—assuming that at least one of the hypotheses would, if true, provide a satisfactory explanation of the fact under consideration. To the second, it says that the hypothesis most likely to be true is the one that scores best on the explanatory virtues: conservatism, modesty, simplicity, generality, and predictive power. Many philosophers have argued against IBE’s answer to the first question. I am interested in an objection to its answer to the second. Many philosophers seem to think that it is unsustainable: they seem to think that even if we assume that one of the competing hypotheses is true, we should not think that IBE will help us to identify it. Or, more carefully, if these philosophers are doing what they appear to be doing—namely, offering critiques of IBE that don’t depend on assumptions about the field of competing hypotheses—then their claim is that IBE will not help us to identify the truth. I believe that this is mistaken: the argument for believing it assumes a model of IBE that we have no reason to accept.

There are many modal epistemologies available to us. Which should we endorse? According to Bob Hale, we can start to answer this question by examining the architecture of modal knowledge. That is, we can try to decide between the following claims: knowing that p is possible is essentially a matter of having a well-founded belief that there are no conflicting necessities—a necessity-based approach—and knowing that p is necessary is essentially a matter of having a well-founded belief that there are no conflicting possibilities—a possibility-based approach. Hale argues for the first of these claims, but I contend that his arguments fail. However, it doesn't follow that we should endorse a possibility-based approach. I repurpose Hale's arguments to show those who would endorse possibility-based approaches need to say more about our modal knowledge concerning logic and mathematics; if they can't, then they ought to endorse a hybrid modal epistemology that doesn't give priority to one modality across the board. Additionally, those who endorse possibility-based views may be committed to Peter van Inwagen's modal skepticism