156 DOGMATISM AND EVOLUTION 



possible correction. To be sure, our present observations cover 

 an enormously wider range and are likewise vastly more delicate; 

 but these differences are differences of degree. An impartial 

 survey of the history of mechanics certainly disposes one to the 

 opinion, that its laws, as compared with those of economics (for 

 example), simply represent a higher level of universality and 

 exactitude probably not the ideal level. 



Various suggestions have been made, looking toward a recon 

 ciliation of the intuitional theory with the facts of history. Two 

 important types of suggestion are worthy of particular notice. 

 The first is the theory of Aristotle and Herbert Spencer, that while 

 the attention of men has been led to mechanical principles along 

 the devious and uncertain paths of observation and induction, 

 yet, when once clearly brought to mind, the principles are intui 

 tively self evident. Spencer s version is modernized by the intro 

 duction of an evolutionary explanation of the origin of the intui 

 tion; and it is reinforced by the consideration that (in the case 

 of all the principles for which he claims a priori certitude) the 

 supposed experimental proofs invariably take for granted in some 

 connection the truth of the principles which they purport to 

 establish universally. This last, however, amounts only to show 

 ing that the principles are tested as working-hypotheses: and 

 the theory remains eminently plausible, but wholly gratuitous. 

 The evolutionary explanation moreover, brings with it the dis 

 quieting suggestion, that while the intuitively known principles 

 may be self-evident, in the sense of producing a quasi-instinctive 

 conviction of their truth, they need not for that reason be wholly 

 removed from reflective criticism. The adaptations which nature 

 produces are commonly no better than they need be with a 

 generous margin of safety, of course. If Newton s first law of 

 motion were no truer than the law that falling bodies tend to 

 move in parallel lines, an intuitive acceptance of it would be no 

 less explicable for that. 



The other type of mediating theory represented most ably 

 by Poincare gives up the hypothesis of an intuition of mechani- 



