290 ANNUAL REPORT SMITHSONIAN INSTITUTION, 193 3 



own number upon nothing less than the law of cause and effect. It is 

 truly remarkable that such an attack should have come not from the 

 antiscientific but from the high priests of science themselves. 



This latest skepticism concerns itself with the behavior of the elec- 

 trons. The phenomena exhibited by these minute bodies have always 

 been in some respects puzzling and incalculable, but scientific thought 

 has been steadily optimistic, confidently awaiting the ultimate solu- 

 tion. The essence of the new view is that the behavior of an electron 

 is incalcidable, not because the problem is as yet too complicated for 

 us, but because, to state it baldly, the actions of individual electrons 

 are not governed by the ordinary law of cause and effect. The new 

 philosophy recognizes that where an individual electron may be at 

 this moment is a matter of observation, more or less imperfect ; it ad- 

 mits that where the electron has been in the past is a matter of his- 

 ory ; but it asserts that where it will be in the future is a matter not 

 for definite prediction but only of statistical probability. 



This doctrine appears to strike at the root of all law and order, and 

 yet, curiously enough, its protagonists recognize the existence of a 

 kind of law on the large scale, but deny that it extends to individual 

 units. The new philosophy is not such a complete reversion to 

 primitive type as might be hastily concluded. 



Perhaps the best illustration that we can give of this new thought 

 is one based upon the behavior of units large enough to be familiar if 

 not altogether comprehensible — human individuals. 



The behavior of any individual under given conditions is, rigidly 

 speaking, unpredictable. For your belief that I will react in a cer- 

 tain way to my environment you have nothing but a probability, 

 perhaps a very liigh one, amounting to what you may consider practi- 

 cal certainty, but never more than a probability. No one can say 

 with absolute certaint}^ that I will not, let us say, steal money during 

 the coming year. It may be in the highest degree unlikely that I 

 will, so unlikely that you may consider it insulting to harbor any 

 suspicion of me, yet experience shows that occasionally an ordinarily 

 well-behaved man may do a most unexpected thing. While no one 

 can say definitely just what you or I or he or she will do, yet with 

 several millions of such individuals to serve as a basis for prediction 

 it is possible to estimate just how many of them will depart from 

 rectitude during the next year and how much money will be in- 

 volved in the total sum. Such is the accuracy of this prediction that 

 bonding companies risk their capital on it year after year, and make 

 money. Individually, man is more or less of an enigma ; in the mass 

 he is a mathematical problem. 



Something very like this is the latest turn of scientific thinking. 

 It asserts that the future behavior of a single electron is incalculable. 

 We cannot tell whether it will turn to the left or to the right, whether 



