558 



LOGIC OF THE MORAL SCIENCES. 



And it is to be remarked that the 

 case is not always one of Composition 

 of Causes : the effect of concurring 

 causes is not always precisely the 

 sum of the effects of those causes 

 when separate, nor even always an 

 effect of the same kind with them. 

 Reverting to the distinction which 

 occupies so prominent a place in the 

 theory of induction, the laws of the 

 phenomena of mind are sometimes 

 analogous to mechanical, but some- 

 times also to chemical laws. When 

 many impressions or ideas are operat- 

 ing in the mind together, there some- 

 times takes place a process of a simi- 

 lar kind to chemical combination. 

 When impressions have been so often 

 experienced in conjunction that each 

 of them calls up readily and instan- 

 taneously the ideas of the whole 

 group, those ideas sometimes melt 

 and coalesce into one another, and 

 appear not several ideas, but one, in 

 the same manner as, when the seven 

 prismatic colours are presented to the 

 eye in rapid succession the sensation 

 produced is that of white. But as in 

 this last case it is correct to say that 

 the seven colours when they rapidly 

 follow one another generate white, but 

 not that they actually are white ; so it 

 appears to me that the Complex Idea, 

 ("ormed by the blending together of 

 several simpler ones, should, when it 

 really appears simple, (that is, when 

 the separate elements are not con- 

 sciously distinguishable in it,) be said 

 to result from, or he generated by, the 

 simple ideas, not to consist of them. 

 Our idea of an orange really consists 

 of the simple ideas of a certain colour, 

 a certain form, a certain taste and 

 smell, &c., because we can, by inter- 

 rogating our consciousness, perceive 

 all these elements in the idea. But 

 we cannot perceive, in so apparently 

 simple a feeling as our perception of 

 the shape of an object by the eye, all 

 that multitude of ideas derived from 

 other senses, without which it is well 

 ascertained that no such visual per- 

 ception would ever have had exist- 

 ence ; nor, in our idea of Extension, 



can we discover those elemenl 

 ideas of resistance derived from oi 

 muscular frame in which it has beei 

 conclusively bhown that the idea ori^ 

 ginates. These, therefore, are ca 

 of mental chenjistry, in which it ii 

 proper to say that the simple ides 

 generate, rather than that they com-' 

 pose, the complex ones. 



With respect to all the other con*^ 

 stituents of the mind, its beliefs, ita^ 

 abstruser conceptions, its sentimenta,j 

 emotions, and volitions, there ai 

 some (among whom are Hartley an<3 

 the author of the Analysis) who thinl 

 that the whole of these are generat 

 from simple ideas of sensation by 

 chemistry similar to that which we] 

 have just exemplified. These philo-i 

 sophers have made out a great par 

 of their case, but I am not satisfie 

 that they have established the whok 

 of it. They have shown that ther 

 is such a thing as mental chemistry : 

 that the heterogeneous nature of 

 feeling A, considered in relation 

 B and C, is no conclusive argumeni 

 against its being generated from " 

 an^ C. Having proved this, thej 

 proceed to show that where A it 

 found B and C were or may hav< 

 been present ; and why, therefore,! 

 they ask, should not A have beei 

 generated from B and C ? But evei 

 if this evidence were carried to th< 

 highest degree of completeness whic 

 it admits of ; if it were shown (whic 

 hitherto it has not, in all cases, been) 

 that certain groups of associated ides 

 not only might have been, but actu-j 

 ally were present whenever the mor 

 recondite mental feeling was experij 

 enced, this would amount only to 

 the Method of Agreement, and could 

 not prove causation until confirmed 

 by the more conclusive evidence of 

 the Method of Difference. If thej 

 question be whether Belief is a mei 

 case of close association of ideas, is 

 would be necessary to examine ex| 

 perimentally if it be true that an] 

 ideas whatever, provided they ar 

 associated with the required degr 

 of closeness, ^ive rise to belief. 



