28 THE BIOLOGICAL PROBLEM 



already shaky determinism has had to undergo another 

 assault, which, however, hke the preceding one, has not 

 practically changed its value as a tool. 



Heisenberg, a brilliant mathematician, formulated in 1927 

 his 'Principle of Indeterminacy' which seriously modified our 

 old ideas, for it introduced a certain degree of indetermination 

 or imprevisibihty of the future, as one of the fundamental 

 postulates of the universe. This different point of view seems 

 to transform the flow of time into a much more tangible 

 phenomenon than it used to be in classical physics. Every 

 moment which passes introduces something new into the world 

 which is not solely a mathematical extrapolation of all that 

 existed previously.^ The classical determinism of Laplace 

 which dominated science for so long stated that, if complete 

 information concerning the entire state of the universe, the 

 position and speed of each element of matter in space during 

 the first minute of the year 1600, for example, could be 

 obtained, it would be possible, by mere calculation, to deduct 

 all the events of the past and of the future. The future is deter- 

 mined by the past, just as the solution of a differential equation 

 is determined by the limiting conditions. Heisenberg demon- 

 strated on the contrary, that only one half of the elements 

 necessary to determine an event can be assembled (speed or 

 position, but not both), as the other elements only come into 

 existence after the accompHshment of the event. It is not 

 ignorance, properly speaking, but a necessary limitation. It 

 is the principle of indetermination which is now fully incor- 

 porated in modern physics. We can easily understand to 

 what a degree this notion upsets the old ideas, even though 



^ There is in Bergson's VEvolution creatrice a remarkable anticipa- 

 tion of the principle of indeterminacy: 'Thus our individuality 

 develops, grows, and matures incessantly. Every moment adds some- 

 thing new to what was before. We will say more: not only new but 

 unpredictable.' These lines were published in 1907, twenty years 

 before Heisenberg. In 191 8 Franz Exner also emitted certain doubts 

 as to the justification of determinism, and E. Schrodinger, who 

 developed the ideas of Louis de Broglie, and like him was awarded 

 the Nobel prize, was alone at that period in supporting Exner's ideas 

 on 'the acausality of phenomena' (1922). See E. Schrodinger, Scie?ice 

 and the Human Temperament, Norton & Co., New York, 1935. 



