Nuanced Arguments

Recently posting something from Butler has started me thinking on issues of nuance and qualification in philosophical argument, and how difficult a time people have trying to follow it. I ran across this problem this summer when teaching Butler, whose arguments are not categorical arguments for categorical conclusions. There is almost always an implicit (and often partially explicit) set of qualifications attached to any conclusion Butler puts forward, at least at some level: "In general, more or less, all things considered, given what we know, for all practical purposes." This last is the key, because practical purposes are the governing feature of Butlerian nuance: the whole point of Butler's reasoning is to get us to a place where, for practical purposes, we can render a categorical assent (where we can simply presume, for practical purposes, that something is true), even if our best speculative reasoning is tenuous, tricky, inconclusive, or incomplete. This is clear from his discussion of presumptive reasoning (still, despite its brevity, the best discussion of presumptive reasoning) in the Introduction to the Analogy. We find it easier to deal with purely speculative arguments that do not involve all the speculative 'ceteris paribus', 'mutatis mutandis', 'more or less', etc., that practical reasoning, and some forms of speculative reasoning of practical importance, implicitly involve on a grand scale; and we particularly find it difficult to see that one can still move on the basis of conclusions so qualified. But it's an aspect of philosophical reasoning that's immensely important, despite its difficulty, and our difficulty in dealing with it properly. In any case, it's interesting to think about what might be done to improve our understanding of such arguments. We need to develop some of Butler's insights into presumptive probability and analogy; we need to pay more attention to the dynamics of cumulative case arguments; and so forth. There's actually been some useful stuff in AI research and cognitive science, in the work on nonmonotonic logics like circumscriptive or negation-as-failure logics, which parallel certain aspects of this sort of reasoning.