THE APPLICATIONS OF SCIENCE 181 



one within the compass of a normal intellect, provided 

 it is well trained. He who seeks to solve the problem 

 without that knowledge and without the training on 

 which it is based, cannot hope for even partial success, 

 unless he can boast the powers of a Galileo or a Faraday. 



And science provides yet another clue. It has estab- 

 lished theories as well as laws. Its theories do not cover 

 the full extent of its laws, and in some sciences little 

 guidance except that of " empirical " laws is available. 

 But where theories exist, they serve very closely to limit 

 the laws by means which it is worth while to try to 

 analyse experience ; no law contradictory of a firmly- 

 rooted theory is worth examining till all other alterna- 

 tives have been exhausted. Here uninstructed inquirers 

 are at a still greater disadvantage, compared with those 

 familiar with the results of science, for while many of the 

 terms involved in scientific laws are vaguely familiar 

 to every one, it is only those who have studied seriously, 

 who have any knowledge of theories. 



Here a word of warning should be given. " Theory " 

 is always used in the book to mean the special class of 

 propositions discussed in Chapter V. When in popular 

 parlance " theory " is contrasted with " practice " it 

 is often not this kind of theory that is meant at all. The 

 plain man I do not think this is an overstatement 

 calls a " theory " anything he does not understand, 

 especially if the conclusions it is used to support are 

 distasteful to him. Arguments about matters in which 

 science is concerned, though they are denounced as wildly 

 " theoretical," often depend on nothing but firmly- 

 established law. It is only because he does not under- 

 stand " theory " that the plain man is apt to compare 

 it unfavourably with " practice," by which he means 

 what he can understand. The idea that something can 

 be " true in theory but false in practice " is due to 

 mere ignorance ; if any portion of " practice," about 



