Professor H. 31. Posnett — On Geological Hypothesis. 301 



the possibility tbat new knowledge may ultimately modify tbe 

 principle as at present held. To keep an open door for all increase 

 of knowledge cannot but aid the cause of scientific progress. Only 

 the survival of dogmatism beyond the conditions that gave it birth 

 and the need of dogmatic teaching in our schools and colleges can 

 account for the continued readiness of some men of science to repeat 

 the old watchword, " It cannot be conceived." 



Let me illustrate my meaning by an anecdote. At Takapuna, 

 near Auckland, is a fresh-water lake, nearly at sea-level, regarded 

 by popular theory as the crater of an extinct volcano. Here, one 

 day, discussing the origin of the lake with some Auckland University 

 students, I was asked, " Has the earth's water-envelope been greater 

 or less in past ages ? Are we justified in assuming the relative 

 conditions of land and water to have been in the past as they are 

 now ? May not both the igneous and the aqueous forces observed 

 by our geologists difier both in degree and kind from the similar 

 forces of a primitive age? " And led on by these questions we soon 

 ventured upon all sorts of heterodoxy, drew imaginary pictures of 

 an evolution of water, of air, of combustion, until we at last came to 

 a conclusion that nature had intended us for the founders of a new 

 science which was to be named "The biology of the elements ancient 

 and modern." 



Twelve years have elapsed since our ideal conversation, and 

 physicists need not be reminded of certain signs now visible on the 

 horizon of knowledge which seem to dimly foreshadow the partial 

 realization of our Takapuna dreams. But it is not my present 

 purpose to discuss new physical hypotheses ; it is merely to say 

 what I then said to our Auckland students : " There is no finality in 

 any hypothesis or law of science, and for this reason, if for no 

 other, it is the duty of every man of science to plainly state every 

 assumption on which his science rests, and to put these statements 

 not in out-of-the-way corners, but in the very front of his scientific 

 teaching or writing." How much the advance of discovery could be 

 aided by the student's early acquaintance with the hypothetical and 

 provisional character of his principles — by the constant reminder of 

 an open door for new observations and new inferences — none but 

 those who hold exaggerated views of the need of dogmatic teaching 

 for the young will fail to perceive. 



The dogmatism of some geological textbooks deserves the more 

 severe censure because there are no textbooks of science more 

 eagerly read by that omnivorous person, ' the general reader ' — none, 

 consequently, more likely, if they contain loose thinking, to difiuse 

 unscientific thought under the name of science. For your ' general 

 reader,' be it noted, is almost as intolerant of hypothesis, plainl}'^ 

 stated as such, as an ancient Hebrew would have been if his rulers 

 had boldly told him, " These useful changes in your barbarous 

 customs we assume to be the will of a divine Lawgiver, because we 

 know that you will not accept the improvement unless it comes to 

 you through the door of this fiction." But rational faith in hypo- 

 thesis — i.e. faith ready at any moment to accept new knowledge and 



