 In retrospect, it is rather difficult to understand the significance that has been accorded this argument. Carnap, for example, in “Introductory Remarks” (Carnap 1956 [Reichenbach 1958: vii]) to the posthumous English translation of this work, singled it out on account of its “great interest for the methodology of physics”. Reichenbach himself deemed “the philosophical achievement of the theory of relativity” to lie in this methodological distinction between conventional and factual claims regarding spacetime geometry (1928: 24 [1958: 15]), and he boasted of his “philosophical theory of relativity” as an incontrovertible “philosophical result”: