168 INDUCTION. 



would violate, are such as to raise a strong presumption of 

 their being the result of causation, the fact which conflicts 

 with them is to he disbelieved; at least provisionally, and 

 subject to further investigation. When the presumption 

 amounts to a virtual certainty, as in the case of the general 

 structure of organized beings, the only question requiring con- 

 sideration is whether, in phenomena so little understood, there 

 may not be liabilities to counteraction from causes hitherto 

 unknown ; or whether the phenomena may not be capable of 

 originating in some other way, which would produce a dif- 

 ferent set of derivative uniformities. Where (as in the case 

 of the flying fish, or the ornithorhynchus) the generalization 

 to which the alleged fact would be an exception is very special 

 and of limited range, neither of the above suppositions can be 

 deemed very improbable ; and it is generally, in the case of 

 such alleged anomalies, wise to suspend our judgment, pend- 

 ing the subsequent inquiries which will not fail to confirm the 

 assertion if it be true. But when the generalization is very 

 comprehensive, embracing a vast number and variety of obser- 

 vations, and covering a considerable province of the domain 

 of nature ; then, for reasons which have been fully explained, 

 such an empirical law comes near to the certainty of an ascer- 

 tained law of causation : and any alleged exception to it cannot 

 be admitted, unless on the evidence of some law of causation 

 proved by a still more complete induction. 



Such uniformities in the course of nature as do not bear 

 marks of being the results of causation, are, as we have already 

 seen, admissible as universal truths with a degree of credence 

 proportioned to their generality. Those which are true of all 

 things whatever, or at least which are totally independent of 

 the varieties of Kinds, namely, the laws of number and exten- 

 sion, to which we may add the law of causation itself, are 

 probably the only ones, an exception to which is absolutely 

 and permanently incredible. Accordingly, it is to assertions 

 supposed to be contradictory to these laws, or to some others 

 coming near to them in generality, that the word impossibi- 

 lity (at least total impossibility) seems to be generally con- 

 fined. Violations of other laws, of special laws of causation 



