The Domain of Physical Science 215 



divisible into three classes — the identical, the statistical, and the 

 transcendental. The " identical laws " include the great field- 

 laws which are commonly quoted as typical instances of natural 

 law — the law of gravitation, the law of conservation of mass and 

 energy, the laws of electric and magnetic force, and the conserva- 

 tion of electric charge. These are seen to be identities, when we 

 refer to the cycle so as to understand the constitution of the entities 

 obeying them ; and unless we have misunderstood this constitution, 

 violation of these laws is inconceivable. They do not in any way 

 limit the actual basal structure of the world, and are not laws of 

 governance. To quote again from Professor Weyl, " The 

 freedom of action in the world is no more restricted by the rigorous 

 laws of field physics than it is by the laws of Euclidean geometry 

 according to the usual view." You have unfettered freedom to 

 draw anything you like on a flat sheet of paper ; all the same, you 

 cannot draw a circle whose circumference is six times its diameter. 

 But you would not complain that because of this inability to do im- 

 possible things your freedom is imperfect. The law of Euclidean 

 geometry is not felt to be a restriction on the freedom of the 

 artist j similarly the law of gravitation, when the nature of that 

 which obeys it is understood, cannot be regarded as a limitation of 

 freedom. The " statistical laws," including the laws of gases and 

 thermodynamics, are the laws obeyed by crowds independently of 

 the characteristics of the individuals composing the crowds. There 

 remain the " transcendental laws," namely, the laws of atomic 

 structure and of the quantum theory, which so far as we know may 

 be true laws of governance. The quantum theory, perhaps even 

 more than the relativity theory, is a remarkable development of 

 the last twenty years, constituting an amazing breach with the 

 traditional type of physical theory. It includes certain precise 

 laws confirmed by innumerable experiments in all branches of 

 physics, but no one has succeeded in forming an intelligible con- 

 ception of the quantum processes One thing is generally accepted, 

 that we here have entered a domain of law of a type to which 

 our experience of the great laws belonging to the first class gives 

 no clue. 



Interference of human free will with the identical laws cannot 

 be admitted ; even omnipotence could scarcely set these aside, 

 and free will does not mean omnipotence. It must be the statistical 

 or transcendental laws that are modified when we " make up our 



