Abstract

For much of this century it was widely assumed in philosophical circles that the relational doctrine of space, time, and motion had finally been established beyond the point of reasonable controversy. In large part this was due to a widespread perception that the theory of relativity is itself a relational theory. Indeed, some of Einstein’s own pronouncements foster this impression. For example, in his definitive formulation of general relativity of 1916, he argued the need for a generalization of the principle of special relativity in order to eliminate the “factitious” causal role he saw inertial frames playing in classical mechanics and special relativity. ‘The laws of physics must be of such a nature that they apply to systems of reference in any kind of motion’. Einstein claimed this requirement is fulfilled by satisfaction of the Principle of General Covariance—that the equations expressing the laws of nature remain valid under arbitrary coordinate substitutions. This, he says, ‘takes away from space and time the last remnant of physical objectivity.’