494 PSYCHOLOGY. 



cau everywhere be reduced to the mere ascertainment 

 that elements present in one fact, in another fail to exist. 

 The perception that an element exists in one thing and does 

 not exist in another and the perception of qualitative differ- 

 ence are, in short, entirely disconnected mental functions.* 

 But at the same time that we insist on this, we must 

 also admit that differences of quality, however abundant, 

 are not the only distinctions with which our mind has to 

 deal. Differences which seem of mere composition, of 

 number, of jplus and minus, also abound.f But it will be 

 best for the present to disregard all these quantitative 

 cases and, taking the others (which, by the least favorable 

 calculation, will still be numerous enough), to consider 

 next the manner in icliich ive come to cognize simple differences 

 of hind. We cannot explain the cognition ; we ctxn only as- 

 certain the conditions by virtue of which it occurs. 



THE CONDITIONS OF DISCRIMINATION, 



What, then, are the conditions under ichich loe discriminate 

 things differing in a simple ivay ? 



First, the things must be different, either in time, or 

 place, or quality. If the difference in any of these regards 

 is sufficiently great, then we cannot overlook it, except by 

 not noticing the things at all. No one can heljD singling 

 out a black stripe on a white ground, or feeling the contrast 

 between a bass note and a high one sounded immediately 

 after it. Discrimination is here involuntary. But where 

 the objective difference is less, discrimination need not so 

 inevitably occur, and may even require considerable effort 

 of attention to be performed at all. 



* Heir G. H. Schneider, in his youthful pamphlet (Die Unterscheidung, 

 1877) has tried to show that there are uo positively existent elements of 

 sensibility, no substantive qualities between which differences obtain, but 

 that the terms we call such, the sensations, are but sums of differences, 

 loci or starting points whence many directions of difference proceed. 

 ' UnterscJiiedsempfindungs-Complexe' a,ve what he calls them. This absurd 

 carrying out of that ' principle of relativity ' which we shall have to men- 

 tion in Chapter XVII may serve as a counterpoise to the mind-stuff 

 theory, which says that there are nothing but substantive sensations, and 

 denies the existence of relations of difference between them at all. 



t Cf. Stumpf, Tonpsychologie, i. 121, and James Ward, Mind, i. 464. 



