Speaking of indicatives, "If A then C" might be asserted because of a belief in the corresponding subjunctive, "Were A the case, C would be the case." What would make us believe that? Probably a belief in some underlying law (of nature) with such consequences. A common way of analysing subjunctives uses possible worlds, and I'm not at all sure about why I don't like them (as they seem suited to many normal uses of subjunctives, e.g. when the apposite law is probabilistically physical), or how I would rather analyse subjunctives (so this is yet another fishing post), but this is certainly an important philosophical topic (so I hope to post more in due course) because analytic philosophy is all about the logical analysis of various hypotheses, about discovering what would be the case under various assumptions (?) But therefore an obvious problem with any sort of possible worlds is that we are naturally going to want to consider what would be the case were there no such possible worlds.