76 THE SCIENCE OF LOGIC 



of consciousness ; causality thus becoming a mere feeling of ex 

 pectation of invariable succession in certain of those states a 

 conviction or belief resulting from the association of repeated 

 experiences. 



Though some of Hume s followers renounced the subjectivity 

 of this view, all alike clung to the notion of invariable sequence of 

 phenomena in time as constituting the essence of causality. &quot; The 

 cause&quot; [of any physical fact, event, phenomenon], writes John 

 Stuart Mill 1 (1806-1873) &quot;is the sum total of the conditions, 

 positive and negative taken together . . . which being realized, 

 the consequent invariably follows. . . . The negative conditions 

 . . . may be all summed up under one head, namely, the absence 

 of preventing or counteracting causes.&quot; Here we have the 

 cause of a phenomenon described as that total group of antecedents 

 which, whenever it is realized, is always followed by that pheno 

 menon. 



But day is invariably followed by night ; yet we do not call 

 it the &quot; cause &quot; of night. Nor do we call night the &quot; cause &quot; of 

 day, though it has been invariably followed by day. This is so, 

 Mill goes on to say, because the sequence here is not absolutely 

 or unconditionally invariable : it is invariable only conditionally 

 upon the conduct or activity of other things upon the rising and 

 setting of the sun in the case contemplated. But invariable 

 sequence is not causality, he tells us, unless the invariability arises 

 wholly and entirely from the nature of the phenomena themselves, 

 is unconditioned by anything extrinsic to the latter, is altogether 

 independent of &quot;whatever supposition we may make with regard 

 to other things,&quot; and will therefore obtain &quot;under all imaginable 

 circumstances &quot; : that is, of course, &quot; as long as the present con 

 stitution of things &quot; 2 endures. Such kind of invariable sequence 

 he terms &quot; unconditional &quot; ; 3 and he then goes on to give his final 

 and scientifically exact definition of &quot; the cause of a phenomenon &quot; 

 as &quot; the antecedent or concurrence of antecedents on which it 

 [the phenomenon] is invariably and unconditionally consequent &quot;. 



By thus defining causation as sequence which is invariable, not 



1 Logic, III., v., 3. Mill properly points out that popular usage generally fixes 

 on some prominent one among those antecedents and applies to it exclusively the title 

 of &quot; cause &quot;. 



2 By this expression Mill tells us that he means &quot; the ultimate laws of nature 

 (whatever they may be) as distinguished from the derivative laws and from the col 

 locations &quot;. op. dt., III., v., 6. 



3 Notwithstanding the condition just set down about the permanence of the 

 &quot; present constitution of things &quot;. 



