i2 4 THE SCIENCE OF LOGIC 



full insight into them, it does not explain them ; for explanation 

 reveals not merely how, or in what manner, an event happens, when 

 it does happen ; but also why it happens (its final cause), and 

 what makes it happen (its origin or efficient cause). And while, 

 as physical scientists, we may seek to establish &quot; physical laws,&quot; 

 in the sense of quantitative descriptions of the relations between the 

 various elements of a given regularly recurring phenomenon, we 

 cannot, as rational beings, rest content with such partial explana 

 tion, but are impelled by our nature to ask ourselves further 

 about the &quot; whence &quot; and the &quot; wherefore &quot; of the whole pheno 

 menon, and so to connect it with all its causes. We cannot help 

 asking those further questions, because the &quot; sufficient reason &quot; 

 of any phenomenon is not to be found in the isolated phenomenon 

 itself, but in the sum-total of all its causes. The Positivist school 

 of philosophers would, indeed, have science study &quot; only the laws 

 of phenomena, and never the mode of production &quot; * of these 

 phenomena by their causes. But science or philosophy will 

 insist on studying the latter. Man z/z//and must seek the causes, 

 both efficient and final, as well as the mere description and 

 measure, of the phenomena surrounding him. And the hypotheses 

 he makes about the causes of any given phenomenon as distinct 

 from those he makes with a view to arriving at a more exact 

 quantitative presentation and description of the constituent parts 

 of the phenomenon have been called, in contradistinction to the 

 latter, Hypotheses of Cause. 



For example, Newton s gravitation hypothesis was an 

 Hypothesis of Law in so far as it simply aimed at giving an 

 exact quantitative expression or description of the various relations 

 of mass, distance, and rate of motion, that make up the whole 

 complex group of phenomena presented to us in our experience 

 of falling bodies and of the motions of the moon and the planets : 

 and in so far as the conception of &quot; gravitation &quot; includes all 

 these phenomena in one common quantitative description, it has 

 been verified, and is now an established &quot;theory &quot;or &quot;law&quot;. 

 That is to say, we now recognize as a verified and accurate de 

 scription of the manner and measure in which these motions of 

 matter occur throughout the universe, the statement that &quot; the 

 acceleration with which any two distant bodies in the universe, 

 Mj and M 2 , tend to move towards each other through space, 



1 WELTON, Logic, vol. ii., p. 91. 



