CAUSE AND EFFECT— PROBABILITY 129 



valuable conception, which throws the idea of cause en- 

 tirely into the field of sense-impressions, into the sphere 

 where we can reason and can reach knowledge. Cause, in 

 this sense, is a stage in a routine of experience, and not 

 one in a routine of inherent necessity. The distinction 

 is, perhaps, a difficult one, but it is all the more needful 

 that the reader should fully grasp it. If I write down a 

 hundred numbers at chance — say by opening carelessly 

 the pages of a book — there results a sequence of numbers 

 beginning, say — 



141, 253, 73, 477, 187, 585, 57, 353, . . . etc., 



in which I cannot predict from any two or three or more 

 numbers those which will follow. The number 477 does 

 not enable me to say that 187 will follow it, the numbers 

 which precede 187 in no way enforce or determine those 

 which follow it. On the other hand, if I take the series — 



I, 2, 3, 4, 5, 6, 7, 8, . . . 



each individual number leads (by addition of i) to the 

 immediately following number, or in a certain sense de- 

 termines it. The first series can, however, be written 

 down so often that we learn it by rote, i.e. that it becomes 

 a routine of experience. The analogy must not, of course, 

 be pressed far, but it may still be of service. There is 

 nothing in any scientific cause which compels us of in- 

 herent necessity to predict the effect. The effect is as- 

 sociated with the cause simply as a result of past direct 

 or indirect experience. Or again, perhaps the matter 

 may be grasped more clearly from a geometrical analogy. 

 If I form the conception of a circle, it follows of inherent 

 necessity that the angle at the circumference on any 

 diameter is a right-angle. The one conception flows not 

 as a result of experience but as a logical necessity from 

 the other. No sequence of sense-impressions involves in 

 itself a logical necessity. The sequence might be chaotic 

 like our first series of numbers ; it has become for us 

 a routine by repeated experience. The noteworthy 

 fact in a routine of perceptions lies not so much in the 



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