It Happened at the Same Time: Salmon and the Conventionality of Distant Simultaneity

Abstract

The focus of Wesley Salmon’s contributions to space-time philosophy lies with questions raised by special relativity theory. The pertinent aspects of his work mainly concern the problem of the empirical determination of simultaneity relations which had received prominent attention in the writings of Logical Empiricists. The famous conventionality thesis advanced in this connection says that judging on the exclusive basis of empirical data, no preferred, unique relation of distant simultaneity can be specified; and since all truth claims are supposed to be based on experience, no factual simultaneity relation exists. The most elaborate development of the conventionality thesis is found in Hans Reichenbach whose writings constitute Salmon’s chief source of inspiration. It does not come as a surprise, then, that the main thrust of Salmon’s work on space-time philosophy is represented by attempts to buttress and support this conventionality claim. So I will concentrate my discussion on that aspect also. But since Salmon does a lot of additional important work in the course of pursuing this overarching goal, I begin with a preliminary section on the relativity of simultaneity. In this area Salmon has produced highly significant insights that are less widely received than they should be. So let me contribute to their dissemination.