138 THE AIM AND ACHIEVEMENTS OF SCIENTIFIC METHOD. 



efface itself. Finally, at any moment it^ at least ideally 

 possible by criticism of the whole construction to separate 

 the primary facts from the interpretative "embroidery," and 

 to realise that the synthesis was not strictly inevitable. 

 Whewell's dictum that " fact and theory have no essential 

 difference except in the degree of their certainty and familiarity. 

 Theory, when it becomes firmly established and steadily lodged 

 in the mind, becomes fact " * which is approved by Professor 

 Deweyf ignores this power of critical analysis. It is, in fact, 

 an early pragmatic pronouncement which, like most pragmatist 

 doctrines, is excellently true within its proper sphere of appli- 

 cation. From the standpoint of the practical man the 

 scientific workman in the engineering workshop, the labora- 

 tory, or the study the theories of his predecessors may 

 often and may well be his facts. No one would censure a 

 Marconi for accepting the Maxwell-Hertz theory of electro- 

 magnetic ether waves as the factual basis of an attempt to 

 biing England and America into wireless telegraphic com- 

 munication ; or a German chemist for directing his search 

 for the means of manufacturing a " natural " perfume in 

 accordance with the stereo-chemical concept of the molecule 

 introduced by Van t'Hoff, or the " ring " concept of Kekule. 

 But the circumstance that theories are often taken with more 

 or less naive conviction as the primary data for sequences of 

 actions in practical life, does not contradict the doctrine, the 

 truth of which is established by^such critical investigations 

 as those of Mach, that all , theories ard ultimately founded 

 upon a solid primary basis of Objective fact, which can, in 

 most cases, be exposed with certainty below the superstructure 

 which ages of man's toil and genius have erected upon it. 



* Whewell, The Philosophy of -the Inductive Sciences, 1840, p. 45. 

 t Op. cit. p. 164. 



