Suppose that we ask the Carnapian (disciple of Carnap) whether Theism is logically possible, and their inclination is to say that it is not. Against this we can advance the following argument:
- Truth is relative to a linguistic framework.
- There is at least one linguistic framework F in which the proposition P is true, where P stands for the proposition: a maximally great being exists.
- Therefore, P is true relative to F.
- Some proposition P’ is possibly true just in case it is true relative to some linguistic framework F’.
- Therefore, P is possibly true.
For the moment, let’s not make the move of demonstrating that from 5 it follows, in any modal logics assuming axiom S5, that a maximally great being does exist. I am inclined to think that the Carnapian won’t object to that statement, and simply argue that from the truth of 5 we can derive the truth of P relative to a logical framework which assumes S5.
However, this is already quite far enough. I suggest that if the Carnapian agrees thus far then we can establish the following: that the Carnapian can accept that P is possibly true such that: were the Carnapian to accept the correspondence theory of truth, they would also accept that P is possibly true in the correspondence sense.
This demonstrates, then, that the Carnapian’s problem with Theism as it is typically and properly understood by the realist, is not that they do not think that Theism is possibly true, but that they do not accept the correspondence theory of truth. Their rejection of Theism being possibly true is actually a rejection of Theism being possibly true in the correspondence sense, and not Theism simpliciter (meaning, as the proposition appears in any language game).
An additional thought: it seems to me that the Carnapian may still be open to persuasion of the Kantian variety. I see no way for the Carnapian to avoid Kant’s conclusion that, even if pure reason cannot carry the mind securely to the metaphysical truth of Theism, practical reason dictates that Theism must be adopted as the only rationally viable assumption given our natural and universal moral values.