EXPERIMENT IN THE SCIENCES 49 



77. In biology, especially in medicine, this process of com- 

 bining inductions is occasionally stigmatized as ' deduction.' 

 Apparently it is held that any inference which unites two or more 

 inductions in a larger synthesis ought to be reached, no matter if 

 impossible, by a single untested inference from particular pheno- 

 mena. This curious opposition between fact and theory is well 

 illustrated by the common declaration that this or that inference, 

 of the truth of which the writer is convinced, " is a fact, not a 

 theory " ; by which is meant only that in the opinion of the writer 

 the inference is incontrovertible, or, in other words, that it is a 

 theory, not a hypothesis. 



78. When, as in mechanics and physics generally, nearly all 

 our accurate knowledge has been gathered in the laboratory, it is 

 often possible to test a new induction by a deductive appeal to 

 other laboratory results which have already been achieved or are 

 possible of achievement. It is largely by such appeals that the 

 facts, inductions, and deductions of physics have been welded into 

 a science. 1 Moreover, since most of the facts are obscured, the 

 field of laboratory discovery is limitless, and, therefore, one experi- 

 mental achievement constantly suggests another, with the result 

 that new facts are continually discovered and new inductions and 

 deductions formulated. 



79. It is different in most branches of biology, So much is 

 already known, or can be ascertained by simple observation, that 

 the opportunities of the laboratory are greatly restricted. If 

 we depend solely on it, if we close our eyes to the universe 

 outside its walls, we may, indeed, reach many valuable facts and 

 inductions. But there will always be the danger that we have 

 wasted our time that the facts have already been reached, or 

 could be reached more quickly, easily, and certainly by simple 



1 It must be borne in mind, however, that physicists have, especially in 

 astronomy, made a very considerable deductive appeal to the material supplied 

 by simple observation. " The use of a scientific instrument does not make an 

 observation into an experiment, unless the instrument modifies the object which 

 is being observed. Thus we invariably speak of observing with a telescope or a 

 microscope" (Welton, Manual of Logic, p. 116). "The attraction of the sun 

 accounted for the motions of the planets ; the attraction of the planets was the 

 cause of the motions of the satellites. But this being assumed, the perturbations 

 and the motions of the nodes and aphelia only made it requisite to extend the 

 attraction of the sun to the satellites and that of the planets to each other ; 

 the tides, the spheroidal form of the earth, the precession, still required nothing 

 more than that the moon and sun should attract the parts of the earth, and that 

 these should attract each other so that all the suppositions resolved themselves 

 into the single one, of the universal gravitation of all matter." (Whewell, 

 Novum Organum Renovatum, p. 92.) 

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