As Jammer discusses in his next chapter, the thesis that any value of e within the range given by Reichenbach is consistent with the physics underlying SR, and thus any specific choice is purely conventional, received much attention after a number of publications by Grunbaum (see, for example, Grunbaum (1973), Chapter 12). Jammer (p. 200) notes that, whereas Reichenbach’s conventionalist position is grounded on epistemological con- siderations, Grunbaum’s is based on ontological ones. Rather than pursuing this issue here, let me turn to the still ongoing debate about whether simultaneity is or is not a matter of convention.