CAUSES IN PRACTICAL REASONING 209 



the cricketer ; but the entire antecedents and con- Book in 

 ditions which have rendered this effect possible 

 comprise not only all the incidents of the cricketer's 

 past training, but the history of cricket itself, and 

 half the properties of matter. It would be impossible 

 and useless to specify all these. When we say that 

 anything is the cause of anything else, we are always 

 selecting that cause out of an indefinite number, on 

 which, for the purpose on hand, it is practically 

 important that we should insist ; and the cause on 

 which it is important that we should insist for For practical 

 practical purposes will be found to be always one 

 which, under the circumstances in view, may or 

 may not be present, 1 which a careless person may 

 neglect to introduce, or an ignorant person be present ; 

 persuaded to take away ; whilst those other causes 

 whose presence is assumed by all parties to the dis- 



1 It was his complete neglect of these considerations that enabled 

 Karl Marx to impose on himself and others his doctrine that the 

 value of commodities depended on the amount of average labour 

 embodied in them a doctrine which is the most remarkable in- 

 tellectual mare's nest of the century. It is perfectly true that if all 

 other circumstances were always equal the demand for the com- 

 modities in question, the ability with which average labour is 

 directed, and the assistance which the genius of the great inventors 

 gives to it it is perfectly true that then the amount of average labour 

 embodied in various commodities would be the measure of their 

 value ; for labour in that case would be the only variant. But, in 

 reality, the important variants are not average labour, but the ability 

 by which labour is directed. The efficiency of labour itself is 

 practically constant ; and for the student of wealth-production the 

 principal force to be studied is the ability of the few, by which the 

 labour of the many is multiplied, and which only exerts itself under 

 special social circumstances. 



14 



