i MENTAL EVOLUTION 15 



then we shall be able to treat the historic development 

 of science as a movement towards the knowledge of reality. 

 If, on the other hand, we take the view that scientific 

 method suffers from incurable defects or limitations which 

 preclude it from ever supplying a genuine interpretation 

 of the reality of things, then clearly we shall put quite a 

 different valuation upon its growth, and our whole estimate 

 of modern civilisation will be vitally changed. Thus from 

 the study of historical facts we are led on to a study of 

 values, of the ultimate grounds of belief, the meaning of 

 rationality, the possible scope of knowledge, the considera- 

 tions which reasonably determine action. We have not 

 only to distinguish successive phases of development, but 

 we have to estimate the direction of development as a 

 whole, and for this purpose we must make use of valuations 

 which open up all the ultimate questions of meaning and 

 validity. It will moreover appear, I hope, in the sequel, 

 that the conception of development in its turn throws no 

 small light on these ultimate questions. The advantage 

 to the two branches of the enquiry is mutual, and if we 

 could arrive at no satisfactory conception of the trend of 

 development without a theory of the rational and the 

 good, it will be found equally that our conceptions, and 

 equally our misconceptions, of the rational and the 

 good are intimately connected with the idea of develop- 

 ment. 



To put the matter very simply, the object of our his- 

 torical enquiry is to measure the growth of mind from the 

 lowest to the highest phase of development. But how are 

 we to know which is highest? The term itself implies a 

 valuation, and unless we have a reasoned standard of value 

 we have no scientific means of determining the terminus 

 ad quern of our narrative. We certainly cannot take our 

 own civilisation as the highest product of the social mind 

 without any dubiety or any reasons given. It does not, 

 to say the least, stand so high in its achievement above 

 some earlier civilisations which arose and flourished and 

 passed away. Human development, it is well to recognise , 

 from the outset, does not proceed continuously in a straight 

 line. If we make the civilisation of our own day the 



