JANUAET 27, 1911] 



SCIENCE 



12g 



ance on seeing in place of reliance on the 

 reading of old authorities. 



To dilate longer before this section of 

 the American Association upon the value 

 of seeing is superfluous. "We have all been 

 trained by dissection and by looking 

 through the microscope, and we will not 

 deny our training, which many of us are 

 engaged in perpetuating. 



Scientific records have a far wider scope 

 than ordinary business records, which 

 merely put down details that can not be 

 carried in the memory. Science strives 

 constantly after new ways of recording 

 and demonstrating facts, which would 

 otherwise be imperfectly known, or not 

 known at all, and at the same time of 

 eliminating the personal factor, by getting 

 the data into a form to assist others in the 

 work of verification. 



Scientific men base their work upon a 

 series of assumptions: first, that there is 

 absolute truth, which includes everything 

 we know or shall know; second, that we 

 ourselves are included in this absolute 

 truth; third, that objective existence is 

 real; fourth, that our sensory perception 

 of the objective is different from the real- 

 ity. These conceptions constitute our fun- 

 damental maxims, and even when not defi- 

 nitely put in words they guide all sound 

 scientific research. Metaphysicians find 

 such maxims interestingly debatable, but 

 science applies them unhesitatingly and is 

 satisfied because their application succeeds. 

 Philosophy, ever a laggard and a follower 

 after her swifter sister, has lately and some- 

 what suddenly termed the scientific habit 

 of work pragmatism and has taken up the 

 discussion of it with delightful liveliness. 

 Let us acknowledge the belated compliment 

 and continue on our way. 



The practical result of the four maxims 

 has been that we further assume that all 

 errors are of individual human origin and 



that there are no objective errors. We 

 make all the mistakes, nature makes none. 

 To render the pursuit of new knowledge 

 successful our basic task is to eliminate 

 error, or in other words to decide when we 

 have sufficient proof. The elimination of 

 error depends primarily upon insight into 

 the sources of error, which, since methods 

 of all sorts are employed, involves an inti- 

 mate technical acquaintance with the 

 methods, with just what they can show, 

 with what they can not show and with the 

 misleading results they may produce. In 

 the laboratory training of a young scien- 

 tific man, one chief endeavor must always 

 be to familia^^ize him with the good and 

 the bad of the special methods of his 

 branch of science. Not until he thor- 

 oughly understands the character and ex- 

 tent of both the probable and the possible 

 errors is he qualified to begin independent 

 work. His understanding must comprise 

 the three sources of observational error, 

 namely, the variation of the phenomena, 

 the imperfections of the methods and the 

 inaccuracy of the observer. The personal 

 equation always exists, although it can be 

 quantitatively stated only in a small mi- 

 nority of cases. 



The history of science at large, the 

 history of each branch of science and the 

 personal experience of every active inves- 

 tigator all equally demonstrate that the 

 greatest source of error is in our interpre- 

 tations of the observations, and this diffi- 

 culty depends, it seems to me, more than 

 upon any other one factor, upon our un- 

 conquerable tendency to let our conclu- 

 sions exceed the supporting power of the 

 evidence. Since generalization is the ulti- 

 mate goal, we are too easily inveigled into 

 assuming probabilities to be certainties, 

 and into treating theories and even hypoth- 

 eses as definite conclusions. Each genera- 

 tion of investigators in its turn spends 



