GROUNDS OF DISBELIEF. 441 



interpositions. To whoever holds this belief, there is a general, presump- 

 tion against any supposition of divine agency not operating through gen- 

 eral laws, or, in other words, there is an antecedent improbability in every 

 miracle, which, in order to outweigh it, requires an extraordinary strength 

 of antecedent probability derived from the special circumstances of the case, 



§ 3, It appears from what has been said, that the assertion that a cause 

 has been defeated of an effect which is connected with it by a completely 

 ascertained law of causation, is to be disbelieved or not, according to the 

 probability or improbability that there existed in the particular instance an 

 adequate counteracting cause. To form an estimate of this, is not more 

 difficult than of other probabilities. With regard to all Jcnown causes ca- 

 pable of counteracting the given causes, we have generally some previous 

 knowledge of the frequency or rarity of their occurrence, from which we 

 may draw an inference as to the antecedent improbability of their having 

 been present in any particular case. And neither in respect to known nor 

 unknown causes are we required to pronounce on the probability of their 

 existing in nature, but only of their having existed at the time and place at 

 which the transaction is alleged to have happened. We are seldom, there- 

 fore, without the means (when the circumstances of the case are at all 

 known to us) of judging how far it is likely that such a cause should have 

 existed at that time and place without manifesting its presence by some 

 other marks, and (in the case of an unknown cause) without having hither^ 

 to manifested its existence in any other instance. According as this cir- 

 cumstance, or the falsity of the testimony, appears more impi'obable — that 

 is, conflicts with an approximate generalization of a higher order — we be- 

 lieve the testimony, or disbelieve it ; with a stronger or a weaker degi-ee of 

 conviction, according to the preponderance ; at least until we have sifted 

 the matter further. 



So much, then, for the case in which the alleged fact conflicts, or appears 

 to conflict, with a real law of causation. But a more common case, per- 

 haps, is that of its conflicting with uniformities of mere co-existence, not 

 proved to be dependent on causation ; in other words, with the properties 

 of Kinds. It is with these uniformities principally that the marvelous 

 stories related by travelers are apt to be at variance ; as of men with tails, 

 or with wings, and (until confirmed by experience) of flying fish ; or of ice, 

 in the celebrated anecdote of the Dutch travelers and the King of Siam. 

 Facts of this description, facts previously unheard of, but which could not 

 from any known law of causation be pronounced impossible, are what 

 Hume characterizes as not contrary to experience, but merely unconforma- 

 ble to it; and Bentham, in his treatise on Evidence, denominates them facts 

 disconformable in specie, as distinguished from such as are disconformable 

 in toto or in degree. 



In a case of this description, the fact asserted is the existence of a new 

 Kind ; Avhich in itself is not in the slightest degree incredible, and only to be 

 rejected if the improbability that any variety of object existing at the par- 

 ticular place and time should not have been discovered sooner, be greater 

 than that of error or mendacity in the witnesses. Accordingly, such asser- 

 tions, when made by credible persons, and of unexplored places, are not dis- 

 believed, but at most regai'ded as requiring confirmation from subsequent 

 observers ; imless the alleged properties of the supposed new Kind are at 

 variance with known properties of some larger kind which includes it; or, 

 in other words, unless, in the new Kind which is asserted to exist, some 



