CHAPTER VII. 



EXAMINATION OF SOME OPINIONS OPPOSED TO THE 

 PRECEDING DOCTRINES. 



1. POLEMICAL discussion is foreign to the plan of this 

 work. But an opinion which stands in need of much illus- 

 tration, can often receive it most effectually, and least tedi- 

 ously, in the form of a defence against objections. And on 

 subjects concerning which speculative minds are still divided, 

 a writer does but half his duty by stating his own doctrine, if 

 he does not also examine, and to the best of his ability judge, 

 those of other thinkers. 



In the dissertation which Mr. Herbert Spencer has prefixed 

 to his, in many respects, highly philosophical treatise on the 

 Mind,* he criticises some of the doctrines of the two preceding 

 chapters, and propounds a theory of his own on the subject of 

 first principles. Mr. Spencer agrees with me in considering 

 axioms to be " simply our earliest inductions from experience." 

 But he differs from me " widely as to the worth of the test of 

 inconceivableness." He thinks that it is the ultimate test of 

 all beliefs. He arrives at this conclusion by two steps. First, 

 we never can have any stronger ground for believing anything, 

 than that the belief of it " invariably exists." Whenever any 

 fact or proposition is invariably believed ; that is, if I under- 

 stand Mr. Spencer rightly, believed by all persons, and by one- 

 self at all times ; it is entitled to be received as one of the 

 primitive truths, or original premises of our knowledge. 

 Secondly, the criterion by which we decide whether anything 

 is invariably believed to be true, is our inability to conceive it 

 as false. " The inconceivability of its negation is the test by 

 which we ascertain whether a given belief invariably exists 



* Principles of Psychology. 



