Weeks 4 and 5 (and beyond!): What is an explanation?
If we’re going to be able to assess IBE’s reliability as a pattern of inference, then we better be able to answer the question, “What is an explanation?” This is more or less a reprise of our earlier question, “What are the dominant views about explanation in the literature?” We’ll approach this in two stages. First, we’ll approach the more abstract question about what we should expect from our theories of explanation (this is a kind of “meta-theory of explanation”). Then, we’ll look at specific theories of explanation.
We’ll begin by looking at Lipton’s quick review of the explanation literature, in Chapter 2 of his book. (I stress that this is a very broad review; the literature gets more detailed very quickly.) Here, Lipton shows that several models of explanation (reason, familiarity, deductive-nomological, unification, and necessity) fail to satisfy several important criteria of adequacy: the why-regress, distinguishing evidence from explanation, asymmetries (i.e. that A explains B typically entails that B does not explain A), etc.
I’ll pair this with two readings that take opposing views about what we should be expecting from a theory of explanation. Nickel (2010) argues against explanatory skepticism. Explanatory skeptics deny the existence of any distinctively explanatory information within or across domains. In other words, explanatory skeptics hold that whether A explains B depends mostly on the background beliefs, commitments, practical interests, etc. of the person who is inquiring about A or B. By contrast, anti-skeptics claim that whether A explains B depends on certain features common to all explanations, regardless of inquirers' background beliefs, commitments, and interests.
While Nickel rejects explanatory skepticism, my collaborators and I show that his arguments are inadequate (Díez,Khalifa, and Leuridan forthcoming). While this does not show that explanatory skepticism is correct, it shows that it is defensible.
And what follows if explanatory skepticism is defensible? Nickel (p. 308) does a nice job discussing three implications of this view: (1) "the special status of understanding is a chimera"; (2) "IBE is undermined," and (3) reduction's status as a "metaphysically important relation" is put into question. Let's also add that Lipton's quick dismissal of the five aforementioned models of explanation becomes far too quick. The skeptic can argue that the criteria of adequacy he uses to knock out these five models at best show that these models aren't universal templates of explanation, but then again, the skeptic will also claim that no such templates exist. Consequently, we are free to adopt the reason model in one context, the familiarity in another, etc., and worries about their susceptibility to why-regresses, asymmetries and the like are also constrained by context-specific interests, background beliefs, etc. Now, it may be the case that these worries crop up more frequently when deploying these kinds of explanations than, e.g. causal explanations, but the skeptic argues that this is simply a contingent fact emerging from most people's attitudes towards explanations, but is not thereby written into the "nature" of explanation.