Abstract
Consider the proposition, “Neither the motion of a body nor the action of a force affects space and time themselves”. We rejected this proposition when, in accepting the general theory of relativity, we accepted that the movement of a body or the action of a force affects the curvature of space-time. Compare the following proposition: “p and if and only if or ”. We think this is logically true; at least, most of us do. Some don’t, on empirical grounds—claiming that we should interpret quantum mechanics as showing that the left-hand side can be true when the right-hand side is false. The idea is that the motions of bodies and actions of forces not only affect space-time relations, they also, as it were, affect logical relations as well. I think evidence from quantum mechanics—like empirical evidence generally—cannot possibly show that the equivalence fails to hold. I am convinced that I know a priori that p and if and only if or. My aim here is to explain the basis of this conviction.