THE DECLINE OF DETERMINISM 



By Sir Arthur Eddington, F. E. S. 



Determinism has faded out of theoretical physics. Its exit has 

 been commented on in various ways. Some writers are incredulous 

 and can not be persuaded that determinism has really been elimi- 

 nated. Some think that it is only a domestic change in physics, 

 having no reactions on general philosophic thought. Some imagine 

 that it is a justification for miracles. Some decide cynically to wait 

 and see if determinism fades in again. 



The rejection of determinism is in no sense an abdication of 

 scientific method; indeed it has increased the power and precision 

 of the mathematical analysis of observed phenomena. On the other 

 hand I can not agree with those who belittle the general philosophical 

 sigmficance of the change. The withdrawal of physical science from 

 an attitude it has adopted consistently for more than 200 years is 

 not to be treated lightly; and it involves a reconsideration of our 

 views with regard to one of the perplexing problems of our existence 

 In this address, I shall deal mainly with the physical universe, and 

 say very httle about mental determinism or free will. That might 

 well be left to those who are more accustomed to arguing about such 

 questions if only they could be awakened to the new situation which 

 has arisen on the physical side. At present I can see little si^^n of 

 such an awakening. Waking is a rude process; and if I sometimes 

 shout It is because current literature resounds with the snores of 

 those who are asleep. 



DEFINITIONS OF DETERMINISM 



Let us first be sure that we agree as to what is meant by determin- 

 ism. I quote three definitions or descriptions for your consideration. 

 I he first is by a mathematician (Laplace) : 



We ought then to regard the present state of the universe as the effect of its 

 antecedent state and the cause of the state that is to follow. An intelligence 

 who for a given instant should be acquainted with all the forces by whicli 

 nature is animated and with the several positi ons of the entities composing it, 



1 Presidential address to the Mathematical Association, 1932. Reprinted bv Dermis 

 sion, from the Mathematical Gazette, vol. 16. No. 21S. May, 1932 



141 



