SIR J. ARTHUR THOMSON 167 



Science may be defined as a criticised and system- 

 atised body of verifiable knowledge, based on observa- 

 tion and experiment, and summed up in the lowest 

 common denominators available at the time. Thus at 

 present the scientific formulations, whether descriptive 

 of states of Being or of processes of Becoming, are in 

 terms of Matter and Energy, Life and Mind. More 

 definitely expressed, the present-day Lowest Common 

 Denominators are Electrons, Protons, Radiations, 

 Protoplasm, and Sentience or "Mind." Science, truly 

 so-called, is always impersonal, that is to say it is 

 verifiable by all normally constituted minds who can 

 use the methods. It is indispensable and irreplaceable, 

 and it includes all orders of facts to which scientific 

 methods can be applied — but the degree of its exact- 

 ness varies with the degree of exhaustiveness attained 

 for the time being by these methods. Thus the 

 present-day science of dreams is very inexact com- 

 pared with the science of astronomy, and the science 

 of psychology is less exact than that of physiology. 



It may seem strange to speak of the unanimity and 

 impersonality of science, when even the man in the 

 street is familiar with the echoes of scientific contro- 

 versy. But most of these controversies have to do 

 with what is still very young science, or with domains 

 where the rigorous application of scientific method is 

 difficult, or with cases where the scientific summing-up 

 has not reached scientific precision, as may be illus- 

 trated by hasty presentations of the Darwinian doc- 

 trine of the Descent of Man. Often, of course, the 

 controversy is not a scientific controversy at all, but a 

 thrust and parry between a hasty scientific generalisa- 

 tion and an unplastic theological conviction. 



