I confess that I'm confused. Why does the "proliferation" of modal logics imply that philosophers do not strive for reductionism? Why think that having several modal logics is a bad thing? These logics were developed originally as purely formal syntactic systems with different sets of axioms. In a sense, decrying the proliferation of modal logics is akin to decrying the proliferation of non-Euclidean geometries. There were modal logics long before philosophers ever spoke of possible worlds, which, unless you're one of the few convinced by David Lewis, philosophers take simply to be a useful heuristic when speaking of possibility and necessity. How can one talk about a purely causal model with some notion of necessity? That would be a purely causal model without any notion of causality. It strikes me that even the AI theorist would like to discuss causation, consistency of models, logical implication, maybe even moral obligation. These are all modal notions, but unfortunately, they're not logically equivalent. We shouldn't fall into a trap of being reductionists purely for the sake of the reduction.