CHAPTER V. 

 HYPOTHESIS : ITS NATURE, FUNCTIONS, AND SOURCES. 



226. FUNCTIONS OF SCIENTIFIC HYPOTHESIS. We have seen 

 that the aim of science is to discover the causes and laws by 

 which we may explain the facts of our experience. Our know 

 ledge of these causes and laws is embodied in universal judgments, 

 and these universal judgments it is the function of induction to 

 establish. But we can neither discover nor verify a universal 

 judgment unless we are first led somehow or other to suspect or 

 suppose it to be true. Such suspicion or supposition we call an 

 hypothesis. 



Not every supposition, however, is an hypothesis in the strict 

 or scientific sense of this term. For example, in order to help 

 our imagination in the study of phenomena due to gravity, we 

 suppose that if the total mass of a body were concentrated in a 

 mathematical point, called the centre of gravity of the body, that 

 point would manifest the same force and have the same weight 

 as the whole body. We imagine the earth as a mathematical 

 point. We conceive its total gravitation-force to be concentrated 

 in that point its &quot; centre of gravity &quot;. We find it easier in this 

 way to measure that force, to bring home to ourselves the law by 

 which it acts on bodies on or near the earth s surface, than if we 

 tried to conceive the several particles of the earth s mass acting 

 each in its own place and independently of the others, on those 

 bodies. But we know, all the time, that the latter is really the 

 case, that our conception of &quot; centre of gravity &quot; has no fact for 

 its object, that the conception is from beginning to end a mere 

 fancy, a purely subjective conception having no other object than 

 an imagined possibility. 1 



Again, in order to help ourselves to conceive great distances 

 or magnitudes we often have recourse to mental images which 

 we call suppositions. To realize the distance of the moon from 



1 C/. MERCIER, Logique, p. 339. 



120 



