3*3^4 INDUCTION. 



CHAPTER XXV. 



OF THE GROUNDS OF DISBELIEF. 



§ 1. The method of aiTiving at general truths, or general propo- 

 sitions fit to be believed, and the nature of the evidence on which they 

 are grounded, have been discussed, as far as space and the wiiter's 

 faculties permitted, in the twenty-four preceding chapters. But the 

 result of the examination of evidence is not always belief, nor even 

 suspension, of judgment; it is sometimes disbelief. The philosophy, 

 therefore, of induction and experimental inquiry is incomplete, unless 

 the gi'ounds not only of belief, but of disbelief, are treated of; and to 

 this topic we shall devote one, and the final chapter. 



By disbelief is not here to be understood the mere absence of belief. 

 I The ground for abstainmg from belief is simply the absence or in- 

 sufficiency of proof; and in considering what is sufficient evidence to 

 support any given conclusion, we have already, by implication, con- 

 sidered what evidence is not sufficient for the same purpose. By dis- 

 belief is here meant, not the state of mind in which we are ignorant, 

 and form no opinion upon a subject, but that in which we are fully 

 persuaded that some opinion is not true ; insomuch that if evidence, 

 even of great strength, (whether grounded on the testimony of others 

 or on our own apparent perceptions,) were produced in favor of the 

 opinion, we should believe that the witnesses spoke falsely, or that 

 they, or ourselves if we were the direct percipients, were mistaken. 



That there are such cases, no one is likely to dispute. Assertions 

 for which there is abundant positive evidence are often disbelieved, on 

 account of what is called their improbability, or impossibility. And 

 the question for consideration is, what, in the present case, these words 

 mean, and how far and under what circumstances the properties which 

 they express are sufficient grounds for disbelief 



§ 2. It is to be remarked in the first place, that the positive evidence 

 produced in support of an assertion which' is nevertheless rejected on 

 the score of impossibility or improbability, is never such as amounts to 

 full proof. It is always grounded upon some approximate generaliza- 

 tion. The fact may have been asserted by a hundred witnesses ; but 

 there are many exceptions to the universality of the generalization 

 that what a hundred witnesses affirm is true. We may seem to our- 

 selves to have actually seen the fact : but, that we really see what we 

 think we see, is by no means an universal truth ; our organs may have 

 been in a morbid state, or we may have inferred something, and 

 imagined that we perceived it. The evidence, then, in the affinnative, 

 being never more than an approximate generalization, all will depend 

 upon what the evidence in the negative is. If that also rests upon an 

 approximate generalization, it is a case for comparison of probabilities. 

 If the approximate generalizations leading to the affirmative are, when 

 added together, less strong, or in other woids, further removed from 

 universality, than the approximate generalizations which support the 

 negative side of the question, the proposition is said to be improbable, 

 and is to be disbelieved, provisionally. If, however, an alleged fact 



