ON THE NOTION OF CAUSE 227 



able evidence. What is actually known, as a matter of 

 empirical science, is that certain constant relations are 

 observed to hold between the members of a group of 

 events at certain times, and that when such relations 

 fail, as they sometimes do, it is usually possible to dis- 

 cover a new, more constant relation by enlarging the 

 group. Any such constant relation between events of 

 specified kinds with given intervals of time between them 

 is a " causal law." But all causal laws are liable to 

 exceptions, if the cause is less than the whole state of 

 the universe ; we believe, on the basis of a good deal 

 of experience, that such exceptions can be dealt with by 

 enlarging the group we call the cause, but this belief, 

 wherever it is still unverified, ought not to be regarded 

 as certain, but only as suggesting a direction for further 

 inquiry. 



A very common causal group consists of volitions 

 and the consequent bodily acts, though exceptions arise 

 (for example) through sudden paralysis. Another very 

 frequent connection (though here the exceptions are 

 much more numerous) is between a bodily act and the 

 realisation of the purpose which led to the act. These 

 connections are patent, whereas the causes of desires are 

 more obscure. Thus it is natural to begin causal series 

 with desires, to suppose that all causes are analogous to 

 desires, and that desires themselves arise spontaneously. 

 Such a view, however, is not one which any serious 

 psychologist would maintain. But this brings us to the 

 question of the application of our analysis of cause to the 

 problem of free will. 



V. The problem of free will is so intimately bound up 

 with the analysis of causation that, old as it is, we need 

 not despair of obtaining new light on it by the help of 

 new views on the notion of cause. The free-will problem 



