XXX INTRODUCTION. 



a hypothesis only probable, perhaps only possible. The 

 facts, the laws of science are true and certain : nothing 

 can be more so. But the same cannot always be said of 

 the interpretations of the facts, of the inferences from 

 the laws, of the temporary tentative hypotheses framed 

 to give some sort of systematic unity or supposed causal 

 connection to a collection of facts or of laws. And some, 

 though by no means all, of the articles of belief fall under 

 this description. They are only hypotheses of different 

 degrees of probability, and consequently of fallibility; 

 whilst one or two,, confidently accepted by Herbert 

 Spencer and Strauss at the hands of the physical specu- 

 lators, do not merit even the name of good hypotheses, 

 being predictions which have yet to be fulfilled from 

 hypotheses which are acknowledged to be uncertain. 

 The articles, in particular, which touch on the religious 

 sphere are mostly inferences without scientific justifi- 

 cation, because from the nature of the case they can 

 never receive that verification by comparison with facts, 

 which Mill, Bain and Lewes, our authorities on the logic 

 of science, insist on as essential to legitimate inference or 

 confident prevision. 



Thus, any one with a moderate acquaintance with 

 physics, who has mastered the principles of inductive and 

 deductive logic as taught by Mill or Bain, may without 

 presumption point out, what some physicists are ready 

 enough to tell us, that the nebular hypothesis of Nature's 

 mode of manufacture of the earth and worlds of space, 

 now somewhat confidently offered as an article of belief, 

 is still only a hypothesis, subject in all its forms, and 

 after all its revisions, to very serious doubts ; while at 

 the best it does not admit of that decisive proof which 

 other hypotheses, at first doubtful, in process of time 

 received. 



And happily, it is still more permissible to doubt the 



