Apeii. 8, 1910] 



SCIENCE 



523 



late laid down, consciously or uncon- 

 sciously, by the investigator. No one, ex- 

 cept the later metaphysicians, has con- 

 vinced us that however tangled the knot of 

 physical facts which we are called upon 

 to explain, the fii'st thing we assume is that 

 these phenomena are subject to law. We 

 assume that we are studying a machine 

 which behaves in a definite manner. 



This assumption— which we may call 

 the mechanical postulate— is not some- 

 thing to be discovered or verified by ex- 

 periment, not something whose adoption 

 stamps a man as a materialist, not some- 

 thing which sane men consider, in order 

 to accept or refuse, but something which 

 all men adopt as a laboratory convenience, 

 one might better say, a laboratory essen- 

 tial. 



Nor is the mechanical postulate one 

 which is confined to physics; but is em- 

 ployed in aU the sciences where men are 

 attempting to bring order out of chaos. 

 It is not, therefore, something to be 

 charged up against one in the sense em- 

 ployed when modern physics is said to rob 

 the world of all spontaneity and senti- 

 ment, or when science is said to be devoid 

 of poetry. While we treat nature as a ma- 

 chine and while we adopt the mechanical 

 hypothesis as a necessity of productive 

 scholarship let us be very careful how- 

 ever not to allow ourselves to dogmatize to 

 the extent of saying that a machine is all 

 we have. 



Is not the physicist under obligations 

 to the philosopher for making this matter 

 perfectly clear? 



Apparent deviations from mechanical 

 law lead to some of the most important 

 biological problems. Animate and inani- 

 mate matter may appear, at first glance, 

 to belong in two different categories; and 

 so they undoubtedly do as regards many of 

 the superficial phenomena. But conversa- 



tion with some of the most productive 

 scholars of our country in zoological and 

 botanical lines has convinced me that they 

 are practically all working on the assump- 

 tion that biological phenomena are physical 

 phenomena. These investigators assure 

 us, moreover, that the introduction of an 

 enteliche here and there, wherever con- 

 venient, would be sufiScient to discoui-age 

 aU serious research on life problems. The 

 same point of view is expressed by Miin- 

 sterberg when, in his classification of 

 knowledge, he places physics and biology 

 together at the very bottom of the group 

 called "physical sciences." 



The hatching of an egg is apparently a 

 different process from that of melting ice, 

 although both are accomplished by the ap- 

 plication of heat. But to assume anything 

 else than that they are both mechanical 

 processes is merely to erect a barrier which 

 shall delay the discovery of truth. The 

 study of cytology and artificial partheno- 

 genesis have already gone so far that the 

 discovery of a much more definite connec- 

 tion between life and mechanics would 

 shock the world perhaps even less than did 

 Wohler's synthesis of urea in 1828. 



UNIFOKMITT POSTULATE 



There is of late a very distinct change of 

 feeling in regard to the principle of the 

 Uniformity of Nature — a principle which 

 was widely circulated, a generation ago, as 

 an experimental fact but which is now 

 properly regarded as another formulation 

 of the mechanical postulate. But, thanks 

 to the metaphysician, this principle is now, 

 so far as I know, regarded by us aU, 

 neither as an axiom nor as an empirical 

 fact, but as a fundamental hypothesis 

 which we may call the "uniformity postu- 

 late." 



This assumption is practically equivalent 

 to considering matter, energy and electrifi- 



