84 INDUCTION. 



rapidly as it does at each new trial; the stage is soon 

 reached at which the chance of unfairness in the die, 

 however small in itself, must be greater than that of a 

 casual coincidence : and on this ground, a practical 

 decision can generally be come to without much 

 hesitation, if there be the power of repeating the 

 experiment. 



When, however, the coincidence is one which 

 cannot be accounted for by any known cause, and the 

 connexion between the two phenomena, if produced 

 by causation, must be the result of some law of nature 

 hitherto unknown ; which is the case we had in view 

 in the last chapter ; then, although the probability of 

 a casual coincidence may be capable of appreciation, 

 that of the counter-supposition, the existence of an 

 undiscovered law of nature, is clearly unsusceptible of 

 even an approximate evaluation. In order to have 

 the data which such a case would require, it would be 

 necessary to know what proportion of all the indivi- 

 dual sequences or coexistences occurring in nature 

 are the result of law, and what proportion are the 

 result of chance. It being evident that we cannot 

 form any plausible conjecture as to this proportion, 

 much less appreciate it numerically, we cannot attempt 

 any precise estimation of the comparative probabilities. 

 But of this we are sure, that the detection of an 

 unknown law of nature of some previously unrecog- 

 nised constancy of conjunction among phenomena 

 is no uncommon event. If, therefore, the number 

 of instances in which a coincidence is observed,, over 

 and above that which would arise on the average 

 from the mere concurrence of chances, be such that 

 so great an amount of coincidences from accident 

 alone would be an extremely uncommon event ; we 



