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SCIENCE 



[N. S. Vol. XXXVII. No. 947 



giving them a place in a world outside of 

 our own conscious selves. In other words : 

 They are endowed with a will of their own, 

 a will that wills not as we will. That all 

 this is a species of the personifying of 

 things, I have myself no manner of doubt. 



But the knowledge of things as gained 

 by the senses in the case of every indi- 

 vidual, can not separate itself from the 

 knowledge gained in the same way by the 

 race of which the individual is a member. 

 The motor reactions underlying the faiths 

 and assumptions, the accumulated contri- 

 butions of the faculties of memory and 

 imagination, as all these are incorporated 

 into the central nervous system, are mat- 

 ters of the development of the race. What 

 even the average school-boy sees and hears, 

 as well as thinks about and reads into his 

 experience with the senses, is not precisely 

 the same as that of the boy in ancient 

 Egypt or Greece, or even the boy among 

 the savage tribes of our own day. Are not 

 the sense-perceptions of the believer in 

 spiritualistic phenomena and in Christian 

 science different from those of the sceptic 

 and disbeliever, to-day, even when we place 

 them in as nearly as possible identical rela- 

 tions to the object to be perceived? Here, 

 then, is where anthropology becomes a val- 

 uable adjunct to any theory of sense-per- 

 ception. 



As to the theory of the relativity of all 

 knowledge as stimulated by and embodied 

 in the maxim that man is the measure of 

 all things, its falsity or truthfulness de- 

 pends entirely upon what is meant by the 

 word "relativity." In the Theaetetus 

 Plato makes Protagoras^ — we do not know 

 with what right — base his doctrine on the 

 philosophy of Heraeleitus. Now, no other 

 philosopher of antiquity has been of late 

 so re-habilitated in reputation and so 

 clothed with honor as has the Ephesian 

 Heraeleitus. He was the founder of nat- 



ural philosophy among the Greeks, the 

 leader of the physicists of the fifth century 



B.C. 



So powerfully impressed was lie with the cease- 

 less change of things, the transitoriness of all the 

 particular, that he sees in it the most universal 

 law of the world, and can only regard the cosmos 

 as being involved in continual change, and trans- 

 posed into perpetually new shapes. All things are 

 in constant flux; nothing has permanence. 



If by the relativity of knowledge, as es- 

 tablished by the psychological and anthro- 

 pological study of man, we mean that no 

 other knowledge is possible for human be- 

 ings than that which comes into relation 

 with human faculties for knowledge, there 

 can be no objection to, or denial of, so 

 obvious a truth. All man's knowledge of 

 mankind and of the rest of the world is 

 human knowledge and comes under the 

 limitations and conditions of all human 

 knowledge. Man's fields of knowledge 

 have boundaries; and what he wins from 

 these must be by patient and skillful using 

 of the means of culture, his own senses and 

 intellect applied to the data of his own 

 experience. 



If by the relativity of knowledge we 

 mean also to ai3i5ert that all knowing is an 

 actual relating, an exercise of the function 

 of relating activity, and that all things 

 known are known as related to other things, 

 we are only stating undoubted psycholog- 

 ical facts. These facts are of fundamental 

 importance in our interpretation of the 

 true meaning of the saying, "Man is the 

 measure of all things." Still further, if 

 we mean that all advance in knowledge, on 

 the part of the individual and of the race, 

 is related to the past stages and achieve- 

 ments of knowing faculty, then, too, we are 

 stating a truth on which psychology and 

 anthropology may cordially unite. But 

 when by the relativity of all knowledge it 

 is meant to imply a complete distrust of 



