6 



SCIENCE. 



[N. S. Vol. XVI. No. 392. 



an irritation; the irritation produces a re- 

 action. Within the ordinary range of the 

 stimuli to which an organism is subjected, 

 the reaction is teleological, that is, it tends 

 to the benefit of the organism. A familiar 

 illustration is the presence of food in the 

 stomach, which produces a stimulus, the re- 

 action to which is manifested by the secre- 

 tion of the digestive fluid for the purpose 

 of digesting the food. An organism might 

 conceivably be maintained solely by this 

 mechanism in cooperation with the physical 

 laAvs which govern all matter. Life in such 

 an organism would be a succession of teleo- 

 logical processes, essentially mechanical 

 and regulated automatically by the organ- 

 ism. By far the majority of biologists 

 regard plants as essentially conforming to 

 this type of life. Whether they absolutely 

 so conform we do not, of course, yet know. 

 A sensation involves the interpolation of 

 consciousness between the stimulation and 

 the reaction, and in consequence there is 

 established the possibility of a higher order 

 of adjustment to the external world than 

 can be attained through the teleological 

 reaction to a stimulus. This possibility de- 

 pends upon the fact that the intervention 

 of consciousness permits an adjustment in 

 accordance not merely with the immediate 

 sensation, bvit also, and at the same time, 

 in accordance with earlier sensations. 

 Thus, for example, the child sees an object, 

 and its reaction is to take hold of the object, 

 which is hot and hurts the child. Later the 

 child sees the object again and its natural 

 reaction is to take hold of it again, but the 

 child now reacts differently because its con- 

 sciousness iitilizes the earlier as well as the 

 present sensation; the previous sensation 

 is dislocated in time and fused with the 

 present sensation and a new reaction fol- 

 lows. No argument is necessary to estab- 

 lish the obvious conclusion that an organ- 

 ism which has consciousness has an im- 

 mensely increased scope for its adjustments 



to the external conditions; in other words 

 consciousness has a very high value for the 

 organism. It is unnecessary to dwell upon, 

 this conclusion, for it will be admitted by 

 every one, except perhaps those who start 

 with the a priori conviction that conscious- 

 ness is an epiphenomenon. 



A sensation gives information concern- 

 ing the external world. Perhaps science 

 has achieved nothing else which has done 

 so much to clarify philosophy as the demon- 

 stration that the objective phenomena are 

 wholly unlike the subjective sensations- 

 Light is a series of undulations, but we do 

 not perceive the undulation as such, but 

 as red, yellow and green, or as we say 

 colors ; the colors give us available informa- 

 tion, and we use them as so many labels, 

 and we learn that reactions to these labels 

 may be helpful or hurtful, and so we regu- 

 late our conduct. Objectively red, yellow 

 and green do not exist. Similarly with the 

 vibrations of the air, certain of which cause 

 the sensation of sound, which is purely 

 subjective. But the sound gives us infor- 

 mation concerning our surroundings, which 

 we utilize for our teleological needs, al- 

 though in nature external to us there is 

 no sound at all. Similarly all our other 

 senses report to us circumstances and con- 

 ditions, but always the report is unlike the 

 external reality. Our sensations are sym- 

 bols merely, not images. They are, how- 

 ever, bionomically sufficient because they 

 are constant. They are useful not because 

 they copy the external reality or represent 

 it, but because, being constant results of 

 external causes, they enable consciousness 

 to prophesy or foresee the results of the 

 reactions of the organism, and to maintain 

 and improve the continual adjustment to 

 the external reality. 



The metaphysicians have for centuries 

 debated whether there is any external ob- 

 jective reality. Is it too much to say that 

 the biological study of consciousness settles- 



