128 INDUCTION. 



different Kinds of things, not allied in any other 

 respect. And as for the properties which, being effects 

 of causes, we are able to give some account of, they 

 have generally nothing to do with the ultimate resem- 

 blances or diversities in the objects themselves, but 

 depend upon some outward circumstances, under 

 the influence of which any objects whatever are 

 capable of manifesting those properties ; as is empha- 

 tically the case with those favourite subjects of Bacon's 

 scientific inquiries, hotness and coldness ; as well as 

 with hardness and softness, solidity and fluidity, and 

 many other very conspicuous qualities. 



In the absence, then, of any universal law of coex- 

 istence, similar to the universal law of causation which 

 regulates sequence, we are thrown back upon the 

 unscientific induction of the ancients, per enumera- 

 tionem simplicem, ubi non reperitur instantia contradic- 

 toria. The reason we have for believing that all crows 

 are black, is simply that we have seen and heard of 

 many black crows, and never one of any other colour. 

 It remains to be considered how far this evidence can 

 reach, and how we are to measure its strength in any 

 given case. 



5. It sometimes happens that a mere change in 

 the mode of verbally enunciating a question, although 

 nothing is really added to the meaning expressed, is 

 of itself a considerable step towards its solution. This, 

 I think, happens in the present instance. The degree 

 of certainty of any generalization which rests upon no 

 other evidence than the agreement, so far as it goes, 

 of all past observation, is but another phrase for the 

 degree of improbability that an exception, if it existed, 

 could have hitherto remained unobserved. The reason 

 for believing that all crows are black, is measured by 



