210 INDUCTION. 



tion to employ the word Cause has occasionally led him to attach less 

 importance than it deserves to this great distinction, upon which alone, 

 I am convinced, the possibility rests of framing a rigorous Canon of 

 Induction. Nor do I see what is gained by avoiding this particular 

 ■word, when M. Comte is forced, like other people, to speak continually 

 of the properties of things, of agents and their action, oi forces, and 

 the like ; terms equally liable to perversion, and which are partial and 

 inadequate expressions for what no word that we possess, except 

 Cause, expresses in its frill generality. I believe, too, that when the 

 ideas which a word is commonly used to convey are overclouded with 

 mysticism, the obscurity is not likely to be so effect,ually dispelled by 

 abstaining from its employment, as by bringing out into full clearness 

 the poition of real meaning which exists in the various cases where 

 the terin is most familiarly employed, and therelay giving a legitimate 

 satisfaction to that demand of the intellect which has caused the term 

 to remain in use. 



CHAPTER VI. 



OF THE COMPOSITION* OF CAUSES. 



§ 1. To complete the general notion of causation on which the rules 

 of experimental inquiry into the laws of nature must be founded, 

 one distinction still remains to be pointed out : a distinction so frinda- 

 mental, and of so much importance, as to require a chapter to itself 



The preceding discussions have rendered us familiar with the case 

 in which several agents, or causes, concur as conditions to the pro- 

 duction of an effect ; a case, in truth, almost universal, there being 

 very few effects to the production of which no more than one agent 

 contributes. Suppose, then, that two different agents, operating 

 jointly, are followed, under a certain set of collateral conditions, by a 

 given effect. If either of these agents, instead of being joined with 

 the other, had operated alone, under the same set of conditions in all 

 other respects, some effect would probably have followed ; which 

 would have been different from the joint effect of the two, and more 

 or less dissimilar to it. Now, if we happen to kijow what would be 

 the effects of each cause when acting separately'from the other, we 

 are often able to arrive deductively, or a priori, at a correct prediction 

 of what will arise fi'om their conjunct agency. To enable us to do 

 this, it is only necessary 'that the same law which expresses the effect 

 of each cause acting by itself, shall also coiTectly express the part due 

 to that cause, of the effect which follows from the two together. This 

 condition is realized in the extensive and impoitant class of phenomena 

 commonly called mechanical, namely, the phenomena of the communi- 

 cation of motion (or of pressure, which is tendency to motion) fr'om 

 one body to another. In this important class of cases of causation, 

 one cause never, properly speaking, defeats or frusti-ates another ; both 

 have their full effect. If a body is propelled in two directions by two 

 forces, one tending to drive it to the north, and the other to the east, , 

 it is caused to move in a given time exactly as far in both du'ections as 



