44 THE PHILOSOPHY OF BIOLOGY 



rustlings and singing noises become apparent even in 

 conditions that ought to preclude all sensation of 

 sound. If we have a bad cold, we do not smell sub- 

 stances which at other times strongly affect our olfac- 

 tory membranes. When we become intoxicated, a host 

 of aberrations of sense displace our normal perceptions 

 of things. 



Our perception of the universe, therefore, depends 

 on the normal functioning of our organs of sense, that 

 is, such modes of functioning as we can describe and 

 communicate to others, and which are thus common 

 to the majority of other men and women. These 

 perceptions resulting from the normal functioning of 

 the organs of sense constitute givenness, and we 

 enlarge, or conceptualise this givenness and call it the 

 subject matter of science. But what is this reality 

 that we say is external to us ? It is, we see, our inner 

 consciousness. If we walk along a road in the dark 

 we can feel what is the nature of the path on which 

 we tread, whether stones or gravel, or sand or grass. 

 But this feeling is obviously not in the soles of our 

 boots, and neither is it in the skin of the feet, for we 

 should feel nothing if the afferent nerves in the legs 

 were severed. Is it then in the brain ? It would 

 appear to be there, but it disappears if certain tracts 

 in the brain are injured. 



All that we can say is that the appearance of reality 

 of things outside ourselves is only the ever-changing 

 condition of our consciousness. This is all that we 

 immediately know, and if we say that there is an 

 universe external to ourselves we thus project outside 

 our own minds what is in them ; and we construct 

 an environment which may or may not exist, but 

 which we have no right to say does exist. A philosophy 

 based on the science of the organism would appear to be 



