Okay so I’ve recently been (briefly) introduced to the idea of propositions containing non-existent entities. The classic example is, of course, “The present king of France is bald.” Here the referent is supposed to be the present king of France, and in affirming or denying the truth-value of the proposition, what we would be doing is affirming or denying whether he has the property of baldness. However, there is no present king of France, so then we use Russell's theory of definite descriptions to work around that issue, so that we don’t presuppose the existence of an entity (the present king of France), but rather, we first ask if there is some arbitrary x, such that x has the property of being the present king of France.
My question is this: what happens if we believe not that the individual is non-existent, but rather, if the predicate is non-existent? Take the proposition “Mary is beautiful.” Let’s assume that I believe that beauty is not a property of Mary, but rather, it’s a sort of a linguistic convention used by people to refer to their belief about a property of Mary, where a roughly equivalent proposition would be “Person X believes Mary is beautiful.” Here we have a referent, namely person X’s cognitive state of belief about Mary. (I'm denying the existence of beauty, because I'm only taking physical attributes like 'brown hair' and 'blue eyes' to have actual existence. Physical things, in other words.)
However, what do we say about the actual proposition “Mary is beautiful” if I am to deny the existence of such properties? Is there some way to work our way around it like Russell does for non-existent individuals? Or do we just say that the proposition lacks truth value, is meaningless, or what? Because if we say "Mary is beautiful" is false, and then conclude that "Mary is not beautiful," that does not seem right. Put another way, if we take the proposition "Mary is not beautiful" as being false (since it's not the case that she has the property of being not-beautiful), then in doing so we would (falsely) conclude that she is beautiful, wouldn't we? But that's obviously not true.