to speak of the increasing probability of correctness of a conclusion, even though general acceptance was given to it before.
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 a§ 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. Soc. Amer., VII., 1896, 8-11.