ANIMAL AND RATIONAL INTELLIGENCE 159 



higher mammalia, or for the fact that rational in 

 telligence belongs to man. 



This is a critical point in the argument. Looking 

 at a dog s brain, we can tell that the animal has been 

 capable of sensory experience, and of locomotion ; 

 and has been distinguished by prominence of the 

 sense of smell. But, with the evidence lying before 

 us in this structure, we cannot tell that the animal 

 was intelligent. The evidence on which we attribute 

 intelligence to the higher mammals is not included 

 within morphology and physiology. Evidence for 

 their classification as mammals is clearly within 

 the compass of these sciences ; evidence for their 

 intelligence is not. For this we are dependent 

 exclusively on observation of the conduct of the 

 animal under our direction. After we have satisfied 

 ourselves that the animal understands our signs, and 

 carries out our wishes, we look in vain within the 

 structure for evidence of the power of understanding 

 we observe. Science has no testimony on this point. 

 Everything said as to brain-power accounting for the 

 dog s intelligence, rests 011 conjecture, not on scientific 

 evidence. The argument from brain structure to in 

 telligence must be withdrawn There is only one line 

 of advance for a scientific argument for continuity, 

 that it be shown that the new function has been con 

 temporaneous with new structure, and that the later 

 function, having been evolved from the earlier, the 

 advance has been continuous. On clearest evidence, 

 sensory experience belongs to all organism ; and 

 diversity of experience depends on differentiation in 

 structure. On the other hand, Intelligence is 

 certainly to be attributed to the higher animals, but 



