398 INDUCTION. 



The validity of all the Inductive Methods depends on the assumption that 

 every event, or the besjinning of every phenomenon, must have some cause ; 

 some antecedent, on the existence of which it is invariably and imcondi- 

 tionally consequent. In the Method of Agreement this is obvious ; that 

 method avowedly proceeding on the supposition that we have found the 

 true cause as soon as we have negatived every other. The assertion is 

 eqxially true of the Method of Difference. That method authorizes us to 

 infer a general law from two instances ; one, in which A exists together 

 with a multitude of other circumstances, and ]3 follows ; another, in which, 

 A being removed, and all other circumstances remaining the same, B is 

 prevented. What, however, does this prove? It proves that B, in the 

 particular instance, can not have had any other cause than A ; but to con- 

 clude from this that A was the cause, or that A will on other occasions be 

 followed by B, is only allowable on the assumption that B must have some 

 c^ise; that among its antecedents in any single instance in which it oc- 

 curs, there must be one which has the capacity of producing it at other 

 times. This being admitted, it is seen that in the case in question that 

 antecedent can be no other than A ; but that if it be no other than A it 

 must be A, is not proved, by these instances at least, but taken for granted. 

 There is no need to spend time in proving that the same thing is true of 

 the other Inductive Methods. The universality of the law of causation is 

 assumed in them all. 



But is this assumption warranted? Doubtless (it may be said) most 

 phenomena are connected as efEects with some antecedent or cause, tliat is, 

 are never produced unless some assignable fact has preceded them ; but the 

 very circumstance that complicated processes of induction are sometimes 

 necessary, shows that cases exist in which this I'egular order of succession 

 is not apparent to our unaided apprehension. If, then, the processes which 

 bring these cases within the same category with the rest, require that we 

 should assume the universality of the very law which they do not at first 

 sight appear to exemplify, is not this a petitio pri7icipu f Can we prove a 

 proposition, by an argument which takes it for granted ? And if not so 

 proved, on what evidence does it rest ? 



For this difficulty, which I have purposely stated in the strongest terms 

 it will admit of, the school of metaphysicians who have long predominated 

 in this country find a ready salvo. They affirm, that the universality of 

 causation is a truth which Ave can not help believing ; that the belief in it 

 is an instinct, one of the laws of our believing faculty. As the proof of 

 this, they say, and they have nothing else to say, that every body does be- 

 lieve it; and they number it among the propositions, rather numerous in 

 their catalogue, which may be logically argued against, and perhaps can 

 not be logically proved, but which are of higher authority than logic, and 

 so essentially inherent in the human mind, that even he who denies them 

 in speculation, shows by his habitual practice that his arguments make no 

 impression upon himself. 



Into the merits of this question, considered as one of psychology, it 

 would be foreign to my purpose to enter here ; but I must protest against 

 adducing, as evidence of the truth of a fact in external nature, the disposi- 

 tion, however strong or however general, of the human mind to believe it. 

 Belief is not proof, and does not dispense with the necessity of proof. I 

 am aware, that to ask for evidence of a proposition which we are supposed 

 to believe instinctively, is to expose one's self to the charge of rejecting the 

 autjbof j^liCtf^ the human faculties ; which of course no one can consistently 



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