n6 THE SCIENCE OF LOGIC 



It was not by supposing &quot; belief in uniformity &quot; to be &quot; by 

 no means the earliest of our beliefs,&quot; but in supposing it to be 

 reached by a certain kind of &quot; inference,&quot; while at the same time 

 supposing this kind of &quot;inference&quot; to depend for its validity on 

 an antecedent profession of this belief, that Mill fell into the 

 fallacy of petitio principii : just as we should fall into the fallacy 

 were we to suppose that our knowledge of the Dictum de omni is 

 an antecedent condition for the validity of the syllogism, and is 

 itself reached by a syllogism. Belief in the uniformity of nature 

 (in the categorical sense) is not a mental assent which must pre 

 cede every induction we make : it is partially embodied in each, 

 and is gradually extended by us to all nature. 



In every scientific induction of a physical law, belief in the 

 uniformity of nature is, therefore, operative. For we embrace 

 the belief that the causes we are dealing with are necessitating 

 causes (i.e. causes invariably followed by the same effects), when, 

 in the first or abstractive stage of the process, we convince our 

 selves, from an observed case or cases, that &quot;the nature A is 

 necessarily connected with the effect a &quot;. l And in the second or 

 generalizing stage, in which we pass from this abstract judgment 

 to the universal judgment, &quot; All A s will always and everywhere 

 produce a&quot; we still more explicitly assent to what is a partial 

 application of the general principle that &quot;in the real order the 

 same cause does always actually produce the same effect&quot;. 2 



But, if the principle of the uniformity of nature is thus shown 

 to be a general expression or summing up of the mental process 

 by which we pass from observed cases, through \\ieabstract, to the 

 universal judgment front &quot;Some (observed) J/ s are P,&quot; through 

 &quot; M as such is P&quot; to &quot;All ATs are P&quot; : is not the self-same 

 principle equally involved in the downward process by which we 

 pass deductively or syllogistically from the universal &quot;All M s 

 are P &quot; to its special applications in the conclusions &quot; These or 

 those S s, which are (other, new, hitherto unobserved) M s, are 



nature &quot; is the ultimate major premiss of all inductions&quot;. He further admits that 

 &quot; it is not, indeed, necessary, in a particular investigation, to assume this uniformity 

 to extend beyond the department of facts with which we are dealing&quot;; but con 

 tends that it is, though only partially applied, nevertheless universally assumed, in 

 every particular induction (p. 407). It is not so assumed explicitly ; but when we 

 come to reflect on the grounds of our inductions we see that the universal principle 

 was implicit or latent in them : that otherwise we could not make our experience 

 intelligible : that our success in making experience intelligible through it justifies 

 our belief in it. 



1 JOYCE, op. cit., p. 219. *ibid. 



