204 THE CASE AGAINST EVOLUTION 



life. The latter are wholly inaccessible to the external senses 

 and perceptible only to the intuition of consciousness, intro- 

 spection, or internal experience, as it is variously called. All 

 our self-knowledge rests on the basis of introspection, and 

 without it the science of psychology would be impossible. In 

 fact, not only psychology, but the physical sciences as well, 

 depend for their validity on the testimony of consciousness; 

 for the external world is only knowable to the extent that it 

 enters the domain of our consciousness. Recently, as we have 

 seen, a tendency to discredit internal experience has arisen 

 among materialistic extremists. This "tendency," to quote the 

 words of Keyser, "most notably represented by the behaviorist 

 school of psychologists (like Professor Watson, for example), 

 is manifest in the distrust of introspections as a means of 

 knowledge of mental phenomena and in the growing depend- 

 ence of psychology upon external observation of animal and 

 human behavior and upon physiological experiment, as if mat- 

 ter were regarded 'as something much more solid and indubi- 

 table than mind' (Bertrand Russell)." — C. J. Keyser, Science^ 

 Nov. 25, 1921, p. 520. Since, however, all our knowledge de- 

 pends on the validity of consciousness, such a tendency is 

 suicidal and destructive of all science, whether physical or 

 psychological. The attempts, therefore, of mechanists, like 

 Loeb, and behaviorists, like Watson, to dispense with con- 

 sciousness overreach themselves. For how can the mechanists 

 know that there are such things as tropisms, tactisms, or 

 reaction-systems, how can the behaviorist study such things 

 as "situations," "adjustments," and S-R-bonds, how can the 

 materialist become aware of the existence of molecules and 

 atoms, except through the medium of their own conscious or 

 psychic states? States of matter can be known only by means 

 of states of mind, and the former, therefore, cannot be any 

 more real than the latter. "What, after all," asks Cardinal 

 Mercier, "is a fact of nature if the mind has not seized, 

 examined, and assimilated it? True, the information of con- 

 sciousness is often precarious. For this reason we do well to 



