Space and Time

It has long seemed to me that the debate between substantival and relationalist concepts of space (time, and spacetime) has been ill-posed. I think Leibniz's relationalism was opposed to substantivalism, but only given some of his other principles, essentially principles in philosophical logic. Logic has changed fundamentally since his day. The same arguments, updated in accordance with modern logic, leeds to a form of relationalism which is not at all an eliminativist one. And I believe the same arguments apply to every other exact symmetry in physics, including gauge and permutation symmetries in quantum theory. See my:

"Indiscernibles, General Covariance, and Other Symmetries", in Revisiting the Foundations of Relativistic Physics: Festschrift in Honour of John Stachel, A. Ashtekar, D. Howard, J. Renn, S. Sarkar, and A. Shimony, (eds.), Kluwer, 2003, which you can download here as a pdf file.

There is another line of thought which I have worked hard to develop. It is that the four-dimensional perspective of special relativity theory already incorporates most of the most unpalatable features of the Everett interpretation. The two are partners in guilt, and if one is prepared to accept Minkowski's framework, in the analysis of time, one no longer has any principled basis on which to reject Everett's framework, in the analysis of probability. This argument is developed in my trilogy of papers in Synthese on "Time and Quantum Mechanics"; see, in particular, my:

"Time, Quantum Mechanics, and Decoherence", Synthese, 102 (1995), 235-66, which you can download here as a pdf file.

On this, see also my Problem of Measurement webpage.

I have found that many physicists, and more than a few philosophers, find this link between the treatment of time in special relativity and the treatment of probability quite incomprehensible, but I am reassured that almost invariably they either deny that special relativity has any particular consequences for the philosophy of time, or fail to understand why anyone should object to the four-dimensional perspective in the first place. I have not attempted to persuade anyone of the latter opinion of the contrary view, for it would run against my own inclination; but on the former I have written now on several occassions. See my How Relativity Contradicts Presentism for my most patient treatment of it.

I should make clear that the situation is in my view quite different in general relativity. But here I have been impressed by Julian Barbour's work. For an idea of what he is about, see my review of his The End of Time in the New York Times Book Review, which you can download here, or go to his Platonia website. (In my language, his claim is that time is an internal relation, a relation which supervenes on the properties of its relata; see again my paper "Indiscernibles..." above.)

Copyright Simon Saunders 2001. Last updated: 19 October 2004.