240 



Thoughts on Causality. 



I build a wall behind my grape-trellis, and I find theripening 

 of the fruit accelerated ; but it is not the wall which does 

 the work ; it is still, as before, the sun. The amount of 

 light emitted by my lamp is determined, within certain 

 limits, by the height of the wick ; but this does not render 

 the wick the cause of the light. The varying wick is only 

 a varying condition of a varying result of a varying activity 

 of a constant physical cause — chemical action between oil 

 and oxygen. Similarly, the amount of thought which I can 

 evolve is conditioned by all the various affections and con- 

 ditions of the brain. My poetry and my philosophy are 

 indeed correlated to brain and blood and oxygen and 

 beef-steak; but only in the same way that my boots are 

 correlated to calf-skin and tan-bark and black- wax. These 

 condition the exercise of the bootmaker's skill ; beef-steak 

 conditions the exercise of mine. It is quite true that the 

 activity in both cases has other conditions ; but it is also 

 true that none of the conditions can be elevated to the 

 dignity of causes. The physical scientist is sometimes 

 hoodwinked by the exact graduation of mental activity 

 to the condition of the brain, and commits the mistake of 

 clothing condition with the character of cause. As well 

 assert that the wick secretes the light. 



A similar departure from correct reasoning is the assign- 

 ment of the "environment " as the cause of organic modi- 

 fications. I shall not deny that organic modifications are 

 generally correlated to the environment, and vary with the. 

 environment, and as a sequence of its variations. Though 

 I have observed that organism bears no fixed, and there- 

 fore necessary, relation to environment, and even some- 

 times ignores it, 1 will assume that the correspondence is 

 always as uniform as a certain school of derivationists 

 picture it. What then ? This is, after all, but a condition- 

 ing cause. It seems to me to imply a lack of close dis- 

 crimination to assert, for instance, that increased cold 

 causes an animal's fur to grow longer. If it grow longer 



