I am a bit puzzled by the modal claims often made concerning the relation between a proposition's being true and its truthmaker existing. Here's one of the sources of my puzzlement.
Suppose you think facts (actual worldly states of affairs) make propositions true. In particular, suppose you think that the fact that Mu and Marks purr is what makes true the proposition All Carrie's cats purr.
Why should you think that it is impossible for the same fact to obtain without making proposition true? Consider a world where I have two more cats besides Mu and Marks, and one of these other cats does not purr. In this world, the fact that Mu and Marks purr still obtains, but does not make true All Carrie's cats purr.
I guess it could be said that the truthmaking fact in the actual world is not the fact that Mu and Marks purr but the fact that all Carrie's cats purr. But I wonder whether this sort of fine-grained individuation of facts is in keeping with the conception of them as worldly states of affairs (which, presumably, are supposed to have some degree of independence of the different ways in which we can represent them).
Why do we want a modal tie between the existence of the truthmaker and the truth of the proposition, anyway? We want truthmakers to have some special relationship to the propositions they make true, of course, but why this sort of special relationship? Wouldn't it be better to drop the claim that a proposition p's truthmaker is something that could not exist without making p true, and say instead that p's truthmaker is that thing in virtue of whose existence p is true? (NB: I intend these all as genuine, i.e. not merely rhetorical, questions!)