1 8 DOGMATISM AND EVOLUTION 



terms admit the probability that one's interpretation is incorrect, 

 one must in each particular case make the most of the best light 

 that one possesses. If any of Plato's arguments appear to the 

 student to be patently unsound, they must pass with him for 

 unsound until he has been convinced of the contrary. And 

 while in the midst of one's reading it may be necessary to lose 

 oneself by a species of dramatic illusion in the thoughts and 

 feelings of the past; still there must be times of afterthought 

 when one attempts to bring past and present together, to sum 

 up the permanent contributions of by-gone schools to one's own 

 world-view. Nevertheless, as we must in the second place re- 

 mark, the significance of these admissions is modified by the fact 

 that the present world-view, by which we judge the past, is 

 itself in process of development. It is not even as if we possessed 

 a fixed body of scientific doctrine, which could be modified only by 

 accretion; that is to say, by the addition of new facts and prin- 

 ciples which should leave the old unchanged and undisturbed. 

 If that were the case, an objective and final criticism of earlier 

 theories would not be so impracticable. But, on the contrary, 

 the progress of science is a true evolution, an organic growth, in 

 which no part is wholly unaffected. Time-honored formulae, 

 even if unrefuted, are narrowed in their field of application, or, 

 by inclusion in more comprehensive generalizations, become pos- 

 sessed of a new significance. Thus, while two and two still make 

 four and doubtless will continue to do so, the science of arithmetic 

 has had a new birth and the general conception of number itself 

 has been transformed, since the establishment by Cantor of the 

 existence of distinct 'transfinite' numbers. 



In the third place, the chief motive which we have for studying 

 the thought of the past is such as to make sympathetic criticism 

 of the greatest possible importance. For that motive is self- 

 knowledge, the analysis of the categories of contemporary 

 thought in the light of their development. The method of analy- 

 sis to be employed is fundamentally the same as is used in genetic 

 investigations of every sort. As a moving object is easier to 



