If we call a tail 'a leg', then how many legs would a horse have? It would still have four. The concepts we use to evaluate the question are our actual concepts, even if the truth of the antecedent (at a closest world w) involves (at w) a revision of our actual concepts. A principle is suggested:
(*) when we evaluate the truth of a counterfactual, the concepts employed (in drawing a path in a close world w from the antecedent to the consequent) are determined by the context of evaluation and not by the semantic facts at w.An analogous principle is this (paraphrased from Jenkins in the comments thread to the last post):
(**) when we evaluate the truth of a counterfactual about logical principles, the logic employed (in drawing a path from the antecedent to the consequent) is determined by the context of evaluation and not by the logical facts at the relevantly close worlds.The idea is that the logic we use to evaluate the truth of a counterfactual is our default logic (ex hypothesi, classical logic), even if the truth of the antecedent (at close worlds) requires an alternative to our default logic. (*) and (**) would seem to stand or fall together.
However, (*) is not unrestrictedly true. Consider:
(1) If 'one' meant two, then 'one plus one' would mean two plus two.If the concepts of evaluation are held fixed, then we should insist that the consequent (i.e. 'one plus one' means two plus two) is false in the closest worlds where the antecedent is true. And so, we should insist that (1) is false. But, (1) is prima facie true. Therefore, (*) is prima facie false as a general principle.
We should then expect that (**) likewise fails as a general principle. It had better fail. Otherwise we cannot engage non-vacuously, when we consider what (logical) principles would be the case if others were not. The reason we can in fact engage non-vacuously about such matters is this. When we evaluate counterfactuals about logical principles, the logic at the closest worlds is relevant to---indeed, is essential for---a proper evaluation of the consequent.