298 DEVELOPMENT AND PURPOSE CHAP. 



axle, and so forth. To ask the ' why ' on these lines is to 

 trace, not the purpose or function but the ' cause,' and to 

 trace back the line of causation is to follow out the category 

 of mechanism. The word is indeed something of a mis- 

 nomer, since few arrangements, if any, are so clearly teleo- 

 logical in their entire nature as a machine. None the less, 

 usage seems, in philosophical nomenclature, to have 

 assigned the term mechanism for the category of explana- 

 tion from which purpose is excluded. Let us endeavour, 

 following the lines of this category, to compare the results 

 point by point with the former. The first point that will 

 strike us is what we may call the indifference of mechanism. 

 When we asked why, i.e. with what purpose, the lever 

 moved, the answer implicated the rest of the machinery 

 and ultimately the purpose which its working subserved. 

 "When we ask why, i.e. for what cause, the lever moves, 

 the answer is immediately, it is attached to an eccentric, 

 and the eccentric rotates on an axle and the axle is turned 

 by a crank and so forth. This line of explanation also in 

 one sense takes in the whole machine bit by bit, but after 

 a different fashion. The mechanical causation of any part 

 of the process proceeds without regard to the surroundings 

 and without respect to the purpose or value of the whole. 

 A given stroke of the lever takes place because the eccentric 

 makes a turn or a portion of a turn. It does not matter 

 whether the engine is working or whether the axle is turned 

 by hand. It does not matter whether the lever is connected 

 with the slide valve or broken off by a sudden accident, 

 it does not matter whether the slide valve, being moved, 

 will admit the steam in the ordinary course, or whether, 

 owing to a dislocation, the motion is futile or harmful. 

 These things will affect the permanent working of the 

 lever. It will not continue to act if the machinery is 

 deranged. But if we fix our minds on a given stroke and 

 ask for its cause, it is a given turn of a particular axle. 

 Given the physical connections, this causal relation will 

 hold, and will hold without regard to any concomitant 

 circumstances or subsequent effects whatever. If we were 

 to analyse it down further into its elements, considering 

 the strains and stresses on rivet and bar, the impacts, the 



