THE PRINCIPLES OF SCIENCE 207 



that science embodies always essential elements of systematic belief. 

 An obdurate defender of his own opinions, Newton is fully aware 

 that no theoretical ideas are susceptible to any perfectly final dem- 

 onstration. 



And although the arguing from experiments and observations by in- 

 duction be no demonstration of general conclusions; yet it is the best 

 way of arguing which the nature of things admits of, and may be 

 looked upon as so much the stronger, by how much the induction is 

 more general. 



Yet Newton also recognizes that, however far beyond possibility of 

 demonstration our best established ideas may lie, it is essential that 

 we cling to them. He indicates the importance he attaches to this 

 view by framing his fourth Rule of Reasoning to run as follows : 



In experimental philosophy we are to look upon propositions inferred 

 by general induction from phenomena as accurately or very nearly 

 true, notwithstanding any contrary hypotheses that may be im- 

 agined, till such time as other phenomena occur, by which they may 

 either be made more accurate, or liable to exception. 



The double thrust of this rule is decisive. From it we gain courage 

 to rely on unprovable theoretical ideas in the design and interpreta- 

 tion of our experiments. In the face of apparent contradictions we 

 defend our theories stoutly, and accept their guidance as we press 

 on to new investigations. But precisely these endeavors, together 

 with Newton's conception that all theoretical ideas are potentially 

 liable to exceptions, may bring us ultimately to a very sceptical re- 

 view of the ideas that have directed our efforts. 



We arrive here at the very core of the principle of corrigible falli- 

 bility. The sense of fallibility encourages detachment, and the capac- 

 ity to recognize error; the sense of corrigibility allows us to proceed 

 hopefully, in full commitment to the ideas we believe well estab- 

 lished. Commitment and detachment, but on somewhat different 

 time scales. In the long term science expresses detachment: nothing 

 is held permanently above all question. In the short term science ex- 

 presses commitment, and this short-term commitment is every bit as 

 important as the long-term detachment. Viewing with detachment is 

 nothing if not backed by acting with commitment. Or, in James' vigor- 

 ous statement: 



