NATURE AND NURTURE 7 1 



ilthough few assert that every response is evidence of knowledge. 

 The impulse to eat when we are hungry is useful, but we do not 

 call it knowledge, although we do give this name to the physiology 

 which tells us when and how far food is beneficial ; and we distin- 

 guish our innate "moral sense" from knowledge of good and evil. 



We are sometimes told by those who are not zoologists, that, 

 admitting that all the responsive actions of living things may be 

 useful, rational responses may nevertheless be distinguished, by 

 perfectibility, from fixed instincts and blind mechanical reflex acts. 

 It is said that while mechanical responses are persistent, those which 

 are due to knowledge are improvable; but no zoologist can admit 

 that any property of living things is immutable, or that perfecti- 

 bility is evidence of knowledge. If the correction of our natural 

 responses and their gradual reduction to exactness by the suppres- 

 sion of those which are confused and perplexed, and the survival 

 of 'those which are distinct and useful were evidence of knowledge, 

 might not the zoologist ask, in this case, whether the whole history 

 of the origin of species by means of natural selection may not be 

 a history or the acquisition of knowledge } For it is a history of 

 the acquisition of something which our reason approves, even if 

 we are quite unable to tell, in most cases, whether it is accompanied 

 by mind or not. Whether perfectibility be held to be evidence of 

 knowledge or not, may not the zoologist ask if the question whether 

 knowledge is or is not innate may not depend upon the answer we 

 give to the farther question whether it is the activity of the organic 

 mechanism, or only the mechanism itself, that is transmitted from 

 parent to child ; for if no act is inherited, is it not hard to see how 

 there can be any innate or hereditary knowledge t 



No one who has propagated plants from cuttings or seen a sea- 

 anemone divide into two, can ask whether a material organism may 

 be multiplied ; but they who hold that actions may be transmitted 

 and multiplied by inheritance seem to hold that the law of the con- 

 servation of energy does not here hold good. While all who hold 

 that this law is empirical and experimental must stand ready to admit 

 exceptions to it when proved, he must be of bold mind who holds 

 that inheritance is an exception ; and we have already, page 59, 

 examined evidence which seems to show that, while the things which 

 living beings do under stimuli are no more than their nature would 



