UNIFORMITY OF NATURE 99 



is no wonder that he regarded it as synthetic, as reached by 

 experience, not as analytic and self-evident like the mere hypo 

 thetical statement of uniformity. If, therefore, the principle of 

 uniformity be understood to assert categorically our belief in the 

 actual existence and operation, throughout space and time, of 

 non-free causes, we have to determine (i) what are the ultimate 

 rational grounds on which we assent to this principle, and (2) 

 what are its relations to the processes of induction and deduction 

 respectively. 



224. ULTIMATE RATIONAL GROUNDS OF OUR BELIEF IN 

 UNIFORMITY: THE SCHOLASTIC, EMPIRICIST, AND IDEALIST 

 VIEWS. Firstly, as to the rational grounds of our assent to 

 the principle. We must bear in mind that it is a synthetic, or 

 a posteriori generalization from experience, about which we have 

 physical certitude. 1 Our concept of physical or non-free cause 

 is not innate. We form it gradually from our acquaintance with 

 uniformity in the processes of physical nature. From our ex 

 perience of the uniform activities of the physical universe we 

 abstract the notion of a necessary or non-free cause, fixed in its 

 mode of action : just as from our internal experience of our 

 own activity, and from observation of the activities of men in 

 general, we abstract the notion of a free or self -deter mining cause, 

 not fixed to one mode of acting in similar circumstances. Hav 

 ing, then, defined for ourselves a non-free or physical cause as 

 &quot; one which will always act the same way, by a necessity of 

 its nature or constitution, in similar circumstances,&quot; we deli 

 berately judge that the causes of which we have experience in 

 physical nature verify our definition : we judge that they will 

 always act the same way in similar circumstances, in the future as 

 in the past, provided something unwonted, extraordinary, unfore 

 seen, does not occur. Thus, while we quite recognize that at least 

 apparent exceptions to uniformity have occurred in the past, that 

 our knowledge of the forces of nature is limited, that some of 

 its phenomena &quot; seem altogether capricious,&quot; 2 that unknown 

 agencies, not calculated by us, may have interfered, and may 

 again interfere, and surprise us by upsetting our expectations: 

 nevertheless, we consider it prudent and reasonable to base upon 



1 C/. MAHER, Psychology (4th edition), p. 420: &quot;The latter generalization [that 

 the laws of nature are constant ] is a contingent truth which we can easily con 

 ceive subject to exceptions &quot;. 



a MILL, op. clt. t III., iii., 2. 



