15 



to say that this kind of necessity is exactly represented by any 

 of those Fundamental Ideas which are the basis of Science ; 

 but yet I think it will be found that this logical necessity 

 mainly operates through the attribution of Names to things ; 

 and that a large portion of its cogency arises from these 

 maxims, that Names must be so imposed that General Pro- 

 positions shall be possible, and so that Reasoning shall be 

 possible. Now these maxims are really the basis of Natural 

 History, and are so stated in the Philosophy of the Inductive 

 Sciences. The former maxim is the principle of all Classifi- 

 cation ; and though we have no syllogisms in Natural His- 

 tory, the apparatus of genus, species, differentia, and the like, 

 which was introduced in the analysis of syllogistic reasoning, 

 is really more constantly applied in Natural History than 

 in any other science. 



Besides the different kinds of necessity which Mr Mansel 

 thus acknowledges, I do not see why he should not, on his 

 own principles, recognize others ; as indeed he appears to me 

 to do. He acknowledges, I think, the distinction of Primary 

 and Secondary qualities ; and this must involve him in the 

 doctrine that Secondary Qualities are necessarily perceived by 

 means of a Medium. Again : he would, I think, acknowledge 

 that in organized bodies, the parts exist for a Purpose; and 

 Purpose is an Idea which cannot be inferred by reasoning 

 from facts, without being possessed and applied as an Idea. 

 So that there would, I conceive, exist, in his philosophy, all 

 the grounds of necessary truth which I have termed Funda- 

 mental Ideas ; only that he would further subdivide, classify, 

 and analyse, the kinds and grounds of this necessity. 



In this he would do well ; and some of his distinctions and 

 analyses of this kind are, in my judgment, very instructive. 

 But I do not see what objection there can be to my putting 

 together all these kinds of necessity, when my purpose re- 

 quires it ; and, inasmuch as they all are the bases of Science, 



