SCIENCE. 



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



sense organs have been multiplied and per- 

 fected in order to supply consciousness 

 with a richer, more varied and more trust- 

 "worthy store of symbols corresponding to 

 external conditions. The nervous system 

 lias grown vastly in complexity in order to 

 permit a constantly increasing variety in 

 the time dislocations of sensation. The 

 motor and allied apparatus have been mul- 

 tiplied and perfected in order to supply 

 consciousness with more possibilities of ad- 

 justment to external reality which might 

 be advantageous. 



If we thus assign to consciousness the 

 leading role in animal evolution we must 

 supplement our hypothesis by another, 

 namely, that conscious actions are primary ; 

 reflex and instinctive actions secondary, or, 

 in other words, that, for the benefit of the 

 organism, conscious actions have been 

 transformed into reflexes and instincts. 

 Unfortunately we must rely chiefly on 

 future physiological and psychological ex- 

 periments to determine the truth of this 

 hypothesis. Its verification, however, is 

 suggested by certain facts in the compara- 

 tive physiology of the vertebrate nervous 

 system, which tend to show that in the 

 lower forms (amphibia) a certain degree of 

 consciousness presides over the functions of 

 the spinal cord, which in mammals is de- 

 voted to reflex actions. Its verification is 

 further suggested by the natural history of 

 habits. As we all know, new actions are 

 performed with difficulty and slowly, but if 

 often repeated they are soon easier and 

 more rapid. If a given reaction to a sen- 

 sation or group of sensations through con- 

 sciousness is advantageous to the organism 

 and the environment is such that the sen- 

 sation is often repeated, then a habit is 

 formed and the response becomes more 

 rapid, and often in ourselves we see habits 

 which arose from conscious action working 

 almost without the participation of con- 

 sciousness, and moreover working usefully 



because rapidly. The usefulness of con- 

 scious reactions is that they are determined 

 not merely by the present sensation but 

 also by past sensations, but they have the 

 defect that they are slow. We can readily 

 understand that it would aid an organism 

 to have the quicker reaction substituted, 

 and we thus recognize a valid teleological 

 reason for the replacement of conscious 

 action by habits in the individual, by in- 

 stincts in the race. The investigation of 

 the evolution of reflexes and instincts is 

 one of the important and most promising 

 tasks of comparative psychology. 



A frank unbiased study of consciousness 

 must convince every biologist that it is 

 one of the fundamental phenomena of at 

 least animal life, if not, as is quite pos- 

 sible, of all life. Nevertheless its consid- 

 eration has barely a place in biological 

 science, although it has long occupied a 

 vast place in philosophy and metaphysics. 

 If this address shall contribute to a clearer 

 appreciation of the necessity of treating 

 consciousness as primarily a problem for 

 biological research to solve, my purpose 

 will be achieved. In an ideal world phi- 

 losophers and scientists would be identical ; 

 in the actual world there are philosophical 

 scientists and scientific philosophers, but 

 in the main the foUowere of the two dis- 

 ciplines pursiie paths which are unfortu- 

 nately distinct. The philosophical mind is 

 of a type unlike the scientific. The former 

 tries to progress primarily by thought 

 based on the data available, the latter seeks 

 to advance primarily by collecting addi- 

 tional data. The consequence of this dif- 

 ference is that philosophy is dependent 

 upon the progress of science, but we who 

 pursue the scientific way make no greater 

 mistake than to underestimate philosophy. 

 The warning is needed. Data of observa- 

 tion are a treasure and verj^ precious. 

 They are the foundation of our mental 

 wealth, but that wealth consists of the 



