THE DISCIPLINARY VALUE OF GEOGRAPHY 119 



to speak of the increasing probability of correctness of a conclusion, 

 even though general acceptance was given to it before. 4 



It is, furthermore, important to recognize that a fundamental but 

 unprovable postulate underlies all this discussion; namely, that the 

 present order of nature is persistent; that is, that time is continuous, 

 and that physical forces have always conformed to the laws which now 

 prevail. For however ingenious or amusing may be the speculations 

 of the metaphysician as to another order of things — for example, as to 

 a past condition of existence in which gravitation worked irregularly 

 and variably, or as to a period of time when energy was created and 

 matter was destroyed in haphazard order, or when time itself began or 

 stopped — the scientist is not concerned with them, because they utterly 

 transcend experience. All his discussions and conclusions as to the 

 events of past time and the origin of the present features of the earth 

 are of no avail, if his essential postulate of the persistence of the 

 present order of nature is erroneous ; but the frank recognition of this 

 fundamental principle need disturb no earnest observer of the face of 

 nature. Whatever doubts regarding the conclusions of science may be 

 expressed by the ingenious metaphysician, with his fancied possibilities 

 as to such inconceivable conditions as the beginning of time or the 

 creation of matter; and whatever dissatisfaction may be expressed, 

 regarding conclusions that are based merely on an unproved postulate 

 and measured only in terms of high probability, by the absolutist who 

 wishes to reach unconditional demonstration in all things, the scientist 

 need not be disconcerted. He must still base all his work on the long 

 accumulated and carefully tested results of thoughtful experience, for 

 his work can have no other base ; and he must accept as satisfying, even 

 if not as absolutely certain in the absolutist sense, those high degrees 

 of probability that are attained by well established theories, for there 

 is no other satisfaction he can reach. 



* " Bearing of Physiography on Uniformitarianism," Bull. Geol. 80c. Amer., 

 VII., 1896, 8-11. 



