CONCLUSION 345 



accepted at the beginning of every scientific inquiry. 

 Therefore it may well be chosen for examination as a 

 test case. 



If the brain contains a physical basis for the nonsense 

 which it thinks, this must be some kind of configuration 

 of the entities of physics — not precisely a chemical 

 secretion, but not essentially different from that kind 

 of product. It is as though when my brain says 7 times 

 8 are 56 its machinery is manufacturing sugar, but 

 when it says 7 times 8 are 6$ the machinery has gone 

 wrong and produced chalk. But who says the machinery 

 has gone wrong? As a physical machine the brain has 

 acted according to the unbreakable laws of physics; 

 so why stigmatise its action? This discrimination of 

 chemical products as good or evil has no parallel in 

 chemistry. We cannot assimilate laws of thought to 

 natural laws; they are laws which ought to be obeyed, 

 not laws which must be obeyed; and the physicist must 

 accept laws of thought before he accepts natural law. 

 "Ought" takes us outside chemistry and physics. It 

 concerns something which wants or esteems sugar, not 

 chalk, sense, not nonsense. A physical machine cannot 

 esteem or want anything; whatever is fed into it it will 

 chaw up according to the laws of its physical machinery. 

 That which in the physical world shadows the nonsense 

 in the mind affords no ground for its condemnation. In a 

 world of aether and electrons we might perhaps encounter 

 nonsense; we could not encounter damned nonsense. 



The most plausible physical theory of correct rea- 

 soning would probably run somewhat as follows. By 

 reasoning we are sometimes able to predict events 

 afterwards confirmed by observation; the mental pro- 

 cesses follow a sequence ending in a conception which 

 anticipates a subsequent perception. We may call such 



