GROUNDS OF DISBELIEF. 375 



be in contratliction, not to any nnmber of approximate generalizations, 

 but to a completed generalization grounded upon a rigorous induction, 

 it is said to be impossible, and is to be disbelieved totally. 



This last princi})le, simple and evident as it appears, is the doctrine 

 which, on the occasion of an attempt to apply it to the question of the 

 credibility of miracles, excited so violent a controversy. Hume's cele- 

 brated principle, that nothing is credible which is contradictory to ex- 

 perience, or at variance with laws of nature, is merely this very plain 

 and harmless proposition, that whatever is contradictory to a complete 

 induction is incredible. That such a maxim as this should either be 

 accounted a dangerous heresy, or mistaken for a groat and recondite 

 truth, speaks ill for the state of philosophical speculation on such sub- 

 jects. 



But does not (it may be asked) the very statement of the proposition 

 imply a contradiction ] An alleged fact, according to this theory, is 

 not to be believed if it contradict a complete induction. But it is 

 essential to the completeness of an induction that it shall not contra- 

 dict any known fact. Is it not then a yclitio priucipii to say, that the 

 fact ought to be disbelieved because the induction opposed to it is com- 

 plete ? How can we have a right to declare the induction complete, 

 while facts, supported by credible evidence, present themselves in op- 

 position to it ? 



I answer, we have that right whenever the scientific canons of in- 

 duction give it to us ; that is, whenever the induction can be complete. 

 We have it, for example, in a case of ciiusation, in which there has 

 been an experimentum crucis. If an antecedent A, superadded to a 

 set of antecedents in all other respects unaltered, is followed by an 

 effect B which did not exist before, A is, in that instance at least, 

 the cause of B, or a necessary part of that cause ; and if A be tried 

 again with many totally different sets of antecedents and B still fol- 

 lows, then it is the whole cause. If these observations or experiments 

 have been repeated so often, and by so many persons, as to exclude 

 all supposition of error in the obsei-ver, a law of nature is established; 

 and so long as this law is received as such, the assertion that on any 

 particular occasion A took place, and yet B did not follow, without 

 anji counteracting cause, must be disbelieved. Such an assertion is not 

 to be credited upon any less evidence than what would suffice to 

 overturn the law. The general truths, that whatever has a beginning 

 has a cause, and that when none but the same causes exist, the same 

 effects follow, rest upon the .strongest hiductive evidence possible ; the 

 proposition that things affirmed by even a crowd of respectable wit- 

 nesses are true, is but an approximate generalization ; and — even if 

 we fancy we actually saw or felt the fact which is in contradiction to 

 the law — what a human being can see is no more than a set of appear- 

 ances ; from which the real nature of the phenomenon is merely an 

 inference, and in this inference approximate generalizations usually 

 have a large share. If, therefore, we make our election to hold by. 

 the law, no quantity of evidence whatever ought to persuade us that 

 there has occuiTed anything in contradiction to it. If, indeed, the evi- 

 dence produced is such that it is more likely that the set of observa- 

 tions and experimetits upon which the law rests should have been in- 

 accurately performed or incorrectly interpreted, than that the evidence 

 in question should be false, we may believe the evidence ; but then we 



