482 THE POPULAR SCIENCE MONTHLY. 



of cerebral activity." The Professor here defends a doctrine from 

 which I rather think Hume would have turned away. With all his 

 skepticism, Hume was fond of dwelling on mental rather than on ma- 

 terial operations. Such sentences show that Huxley may be properly 

 called a materialist. He denies, indeed, that he is a materialist. The 

 fact is, that he is an agnostic, believing in neither mind nor matter as 

 substances. But then he makes all agency material. " The roots of 

 psychology lie in the physiology of the nervous system." He gives 

 a physical basis to all mental action inconsistently, I think, for I can 

 not find that on his principles he is entitled to seek for any basis. 

 Neither reason nor experience sanctions the doctrine that matter can 

 produce mind ; that molecules or masses of matter can think or feel, or 

 discover the distinction between good and evil. At this point Huxley 

 seems to separate from such men as Tyndall and Du Bois-Reymond, 

 who tell us that to bridge the wide gulf that divides mind from matter 

 is altogether beyond human capacity or conception. 



5. At this point it will be necessary to refer I can do so only 

 briefly to the question so important in philosophy, as to whether the 

 mind discovers some objects and truths at once, and without a process 

 that is, by intuition. Hamilton, in his famous Note A, appended to 

 his edition of Reid's " Collected Works," has shown that all thinkers, 

 including even skeptics, have been obliged to assume something with- 

 out proof, and to justify themselves in doing so. In my " Examina- 

 tion of Mr. J. S. Mill's Philosophy " I have shown that, in his " Exam- 

 ination of Hamilton's Philosojahy," he has assumed between twenty 

 and thirty such principles. With Locke I hold that the primary mark 

 of these intuitions is self -evidence. We perceive things and truths by 

 simply looking at them. Intuitions are not high a priori truths inde- 

 pendent of things, but they are involved in the very nature of things, 

 and we perceive this as we look at them. Thus we know, by simply 

 looking at them, that things exist ; that if two straight lines placed 

 alongside proceed an inch without coming nearer each other, they 

 will not approach nearer, though prolonged through all space ; that 

 two things plus two things make four. Truths thus self-evident to 

 our minds become necessary ; we can not be made to judge or decide 

 that they are not true. Necessity is commonly put forward by meta- 

 physicians such as Leibnitz and Kant as the test of such truths. I 

 regard it as the secondary, the primary being self-evidence. 



Hume and Huxley have discussed the question of Necessity espe- 

 cially as applied to causation. Hume accounts for it by custom and 

 association of ideas : we are accustomed to see cause and effect to- 

 gether, and when we see the one we are constrained, whether we will 

 or not, to think of and expect the other. But this is not the kind of 

 necessity which metaphysicians appeal to. Necessity as a test of truth 

 is a necessity of cognition, belief, or judgment, arising from our view- 

 ing the nature of the object, as, for example, when on contemplating 



