380 THE REAL WORLD 



part of a tide of change which, in its instance, has been latterly and, 

 we may think, still is, running like a mill-race. ... It is being made 

 along with our planet's making. We do not know that it e\'er will be 

 finished. 



Ultimate unintelligibilities? Because (by the margin of their postu- 

 lates) scientific theories cannot offer us complete explanation, there- 

 fore they offer us no explanation. This seems the tenor of Mach's 

 argument, and it is again a complete non sequittir. Quite evidently a 

 few stipulated postulates do explain a vast multitude of derivative 

 laws and concepts. Furthermore these explanations do satisfy a cri- 

 terion of genuineness not met by explanations in terms, say, of Ho- 

 meric gods. Consider that the ferocity of the warrior is then ascribed 

 to the inspiration of fierce Ares; the passion of the lover, to amorous 

 Aphrodite; the insight of the sage, to wise Athena; and so on. To 

 gods generally are imputed the very qualities that are to be ex- 

 plained: the problems at issue are, as it were, "pushed upstairs." It 

 is not so in science. Here explanation is both genuine and continu- 

 ously progressive. 



As a great many lesser theories, all with their own postulates, are 

 displaced or subordinated by a few more comprehensive theories, 

 progress in scientific explanation becomes obvious in the reduced 

 number of postulates that must be stipulated but are not themselves 

 explained. Less obvious but not less significant, I think, is a pro- 

 gressi\'e change in the character of the stipulated postulates. More 

 and more these tend to assert identities— YRnging from the constancy 

 of the velocity of light and the form of physical laws postulated by 

 relati\dty theory, to the immutability of atoms hypothesized to ex- 

 plain qualitative change. Meyerson suggests that postulated identi- 

 ties dont need further to be explained. For is not identity an ultimate 

 explanation we find wholly intelligible in itself? Rejecting atomic 

 theories on other grounds, Mach would of course insist that the im- 

 mutability {i.e., identity in time) of the bodies they postulate is only 

 a common i/n-intelligibility. But I find that Mach offers, and I sus- 

 pect he could offer, no demonstration of unintelligibility. And the 

 burden of proof still lies hard upon his followers, since the demon- 

 strated heuristic power of atomic theories strongly suggests that, in 

 fact, we find their postulates quite clearly enough intelligible to 

 draw from them predictions of strange things totally unknown but 

 later discovered. 



