202 



SCIENCE 



[Vol. V., No. 109. 



of the use of axioms appears, according to our 

 author, in the fact that the learner, from long 

 habit (not, as Mach thinks, from any a priori 

 insight) , has come to expect instinctively, and 

 so to conceive very economically, certain simple 

 sequences of facts. Purely for economic rea- 

 sons, and not on philosophic grounds, nor for 

 that matter with any philosophic justification, 

 the teacher is disposed to seize upon these ele- 

 mentary facts as the constituents into which 

 more complex facts can be analyzed, and by 

 which these cases can be easily described. 

 These simpler sequences are chosen simply 

 because the learner already knows of them, 

 and can more readily grasp them. When one 

 calls them a priori, one forgets how easily a 

 puzzling question can confuse us about their 

 meaning, and even about their truth. Their' 

 self-evidence is the self-evidence of instinct, 

 and they are in no philosophical sense a priori. 



After the foregoing summary, we may fairly 

 assert that in one respect, at any rate, Mach's 

 method is praise worth}' ; and that is, in its 

 tendency to get rid of the mysterious element 

 of his science. Whatever one may hold about 

 the a priori in general, there is no doubt that 

 we have had enough and too much of the 

 purely mystical a priori. If there is any 

 fundamental rational truth at the bottom of 

 science, if science is more than a mere aggre- 

 gation of facts, this rational basis, when we 

 come to state it, must be as frank and honest 

 and manly a principle as the most common- 

 place adherent of the empirical philosophy 

 could desire. The old-fashioned a priori, in 

 science, in morals, in religion, used to be 

 represented as an arrogant and intolerant 

 thing, mysterious in its manner of speech, 

 violent and dogmatic in its defence of its own 

 claims. The English empiricists used to hate 

 this aristocratic a priori, and they shrewdly 

 suspected it to be a humbug. What they 

 gave us in its place, however, was a vague and 

 unphilosophic doctrine of science, that you 

 could only seem to understand, so long as you 

 did not examine into its meaning. 



Mach's view avoids the mystery of the old 

 a priori. He leaves us still the mysteiy of the 

 correspondence of external nature to our fun- 

 damental interests in the simplicity of its phe- 

 nomena. Yet this mystery has the look of the 

 genuine philosophic problem. The new empir- 

 icism is not and can not be final ; but it prom- 

 ises to prove an excellent beginning, and one 

 can at least commend it to those instructors 

 in elementary mechanics who still puzzle their 

 pupils with their use of the old-fashioned, 

 mystical a priori. Mach's fundamental prin- 



ciple of the economy of thought is one that 

 any intelligent pupil, with a few empirical 

 facts before him, could be got to understand. 

 But, as many not extraordinarily stupid pupils 

 have so often felt, the mysterious way in which 

 such axioms as the ' principle of sufficient 

 reason ' used to appear, aimlessly wandering 

 to and fro in the text- books, could not but per- 

 plex, without in any wise helping, the young 

 mind. That even to-day, when the empirical 

 methods in elementary mechanics are so well 

 developed and so generally used, the ' princi- 

 ple of sufficient reason ' is occasionally called 

 in to help teachers and text-books out of dif- 

 ficult places, — this fact is surely a ' sufficient 

 reason ' in itself for a careful stud}" of such 

 books as Mach's. There are man}' teachers 

 of elementary mechanics to-day, who, while 

 abhorring metaphysics, and constantly glorify- 

 ing experience, never know or can tell just 

 what ought to be done with that ' principle of 

 sufficient reason,' which, however, as it used 

 to be applied when it held sway in elementary 

 mechanics, was the most miserably ' metaphys- 

 ical ' of all confused statements. The most 

 ardent believer in the rational a priori must 

 therefore delight to find, in such a book as 

 Mach's, the foundation laid for future philo- 

 sophic inquiry in the clear and sensible empiri- 

 cism of the author, tentative and transient 

 though this doctrine itself may prove. Only 

 when the vague and mystical have been ban- 

 ished from the mere terms and axioms of the 

 science, can a philosophic student hope suc- 

 cessfully to grapple with the question, " How 

 is empirical science, with certain and fixed 

 results, possible at all? " Every one is there- 

 fore interested in such undertakings as our 

 author's, whether one is student of mechanics 

 or of logic, or teacher of either ; for every one 

 is interested in plain and frank thinking, free 

 from appeals to merely mystical principles. 



In concluding, we must call special attention 

 to our author's discussion of the question of 

 absolute and relative motion, which he seems 

 to us to have treated with marvellous skill ; and 

 thus we are obliged unwillingly to leave a book 

 that is so full of learning and suggestion. 



THE SNAKE-DANCE OF THE MOQUIS. 



Capt. Bourke has given us here a most in- 

 teresting account of his experience among the 



The snake-dance of the Moquis of Arizona ; being a narrative 

 of a journey from Sante Fe, New Mexico, to the villages of the 

 Moqui Indians of Arizona, with a description- of the manners 

 and customs of this peculiar people, and especially of the revolt- 

 ing religious rite, the snake-dance. By John G. Bourke, cap- 

 tain third U.S. cavalrv. New York, Charles Scribner's sons, 

 1884. 371 p., 31 pi. 8°. 



