CAUSATION 



ginning of a phenomenon is what implies a 

 cause, and causation is the law of the succes- 

 sion of phenomena. ... I have no objection 

 to define a cause, the assemblage of phenomena, 

 which occurring, some phenomenon invariably 

 commences, or has its origin. Whether the 

 effect coincides in point of time wdth, or imme- 

 diately follows, the hindmost of its conditions, 

 is immaterial. At all events it does not precede 

 it ; and when we are in doubt, between two co- 

 existent phenomena, which is cause and which 

 is effect, we rightly deem the question solved 

 if we can ascertain which of them preceded the 

 other." ' 



Secondly, invariableness of sequence is given 

 in our experience of causation. Invariableness 

 is the chief mark by which we distinguish those 

 sequences which are causal from those sequences 

 which are commonly termed accidental. The 

 well-known fallacy o^ post hoc, ergo propter hoCy 

 upon which are founded most of the current 

 hygienic and therapeutic vagaries which claim 

 to be upheld by experience, arises from the neg- 

 lect of this essential distinction. It lumps to- 

 gether all kinds of sequence under the general 

 head of causation. If drinking a cup of coffee 

 is followed by headache, or if a troublesome fit 

 of indigestion ends after taking a dose of patent 

 medicine, it is rashly inferred that the coffee 



^ Mill, System of Logic, 6th edition, vol. i. p. 584. 

 221 



