In this paper a method is proposed for empirically determining simultaneity at a distance within the special theory of relativity. It is argued that this method is independent of Einstein's signalling method and provides a basis for denying the conventionality of distant simultaneity.

Robert Torretti's objection is verificationism writ large. We reply that verificationism is to be rejected. Carlo Giannoni's objection is that our test for tilting fails because the rod might tilt and yet no current flow through its mid-point. We reply that nevertheless we can test for tilting because there would still be differences detectable with a glavanometer.

In their recent paper, Jackson and Pargetter have attempted to prove that simultaneity is not a matter of convention. They attempt to show that it is an empirical fact whether or not a moving rod A′B′ is perpendicular to a plane XY. If it is an empirical fact, then such a perpendicular rod can be used to synchronize clocks. We shall show that it is not an empirical fact, but it is in fact synchronization dependent.

Frank Jackson and Robert Pargetter propose a method for synchronizing clocks at rest at distant points of an inertial system in Euclidean space, which, they claim, does not depend on Einstein's signalling method and provides a basis for denying the conventionality of distant simultaneity. I am afraid, however, that the new method presupposes that the simultaneity of distant events relatively to the chosen inertial system has been already determined by Einstein's or some other method. Jackson and Pargetter describe their method (...) as follows: Let UA, UB be clocks at A, B, respectively. Let XY be an axis perpendicular to AB, passing through C, the midpoint of AB. Take a rigid straight rod A′B′ with midpoint C′ and length equal to the length AB. Move A′B′ with uniform velocity such that C′ travels along XY towards C, and A′B′ is perpendicular to XY ; then if the reading … on UA just when A′ coincides with A is the same as the reading … on UB just when B′ coincides with B, clocks UA and UB will be synchronous.. (shrink)