ABSTRACTION. 



CHAPTER 11. 



OF ABSTRACTION, OR THE FORMATION OF CONCEPTIONS. 



§ 1. The metaphysical inquiry into tlie nature and composition of 

 what have been called Abstract Ideas, or in otlier words, of the notions 

 which answer in the mnid to classes and to general names, belongs not 

 to Logic, but to a dift'erent science, and our purpose does not require 

 that we should enter upon it here. We are only concerned with the 

 universally aclcnowledged fact, that such general notions or concep- 

 tions do exist. The mind can conceive a multitude of individual things 

 as one assemblage or class ; and general names do really sug<»-est to us 

 certain ideas or mental representations, otherwise we could not use the 

 names with consciousness of a meaning. Whether the idea called up 

 by a general name is composed of the various circumstances in which 

 all the individuals denoted by the name ?igree, and of no others, 

 (which is the doctrine of Locke, Brown, and the Conceptualists) ; or 

 whether it be the idea of some one of those individuals, clothed in its 

 individualizing peculiarities, but with the accompanying knowledo-e 

 that those peculiarities are not properties of the class, (which is the 

 doctrine of Berkeley, Dugald Stewart, and the modern Nominalists); 

 or whether (as held by Mr. Mill), the idea of the class is that of a 

 miscellaneous assemblage of individuals belonging to the class ; or 

 whether, finally, (what appears to be the truest opinion) it be any one 

 or any other of all these, according to the accidental circumstances of 

 the case ; certain it is, that some idea or mental conception is suggested 

 by a general name, whenever we either hear it or employ it with con- 

 sciousness of a meaning. And this, which we may call if we please a 

 general Idea, rejrresents in our minds the whole class of things to which 

 the name is applied. Whenever we think or reason concerniu"- the 

 class, we do so by means of this idea. And the voluntary power 

 which the mind has, of attending to one part of what is present to it 

 at any moment, and neglecting another part, enables us to keep our 

 reasonings and conclusions respecting the class unaffected by anything 

 in the idea or mental image which is not really, or at least which we 

 do not really believe to be, common to the whole class. 



We have, then, general conceptions: we can conceive a class as a 

 class. But this appears to me to be a fact which Logic, as such, may 

 fairly be permitted to take for granted, without any particular exami- 

 nation into the manner of it. Logic is concerned with what we carr 

 know, and with what we can assert, but not with what we can con- 

 ceive. We can speak and reason of a number of objects as a class, 

 and we can know them to bo a class, and know what makes them so; 

 and it is enough for Logic to und<!rstand this, and to know that the 

 mind has whatever powers this implies, without incjuiring what powers 

 these are. However, if we are forced to enter upon this foreign 

 ground, it cannot but be admitted that there are such things as general 

 conceptions, and that when we form a set of phenomena into a class, 

 that is, when we compare them with one another to ascertain in what 

 they agree, some general conception is implied in this mental opera- 

 tion. And inasmuch as such a compaiison is a necessary preHminary 



