9 



arguments, which are also so related as to produce physically, in 

 the common way of cause and effect, partial convictions, or per- 

 haps most commonly, belief mixed with doubt. The latter kind 

 of evidence, viz. the means by which belief is produced, is not to 

 be considered. 



20. We gain the belief of an existence either by the imme- 

 diate operation of an external object upon our senses, or by a 

 process of our own minds: the strength of evidence must always 

 be proportionate to the strength of belief. In our examinations 

 respecting the existence of things, our object is to improve our evi- 

 dence, to substitute that which produces a certain for that which 

 produces a doubtful conclusion. We can look for no higher 

 satisfaction, with respect to things, than that we should possess 

 with regard to them the most perfect belief; we can propose to 

 ourselves no higher object of investigation. 



21. It may be objected that universal scepticism must be a 

 consequence of this doctrine : for if, it may be urged, there is no 

 other testimony of the existence of externals, but our belief of 

 such existence; and if the strongest belief is liable, perhaps in 

 rare instances, to be superseded by a different one; how, ad- 

 mitting this principle, can we feel assured of the reality of any 

 thing beyond ourselves, or even of our own existence? I reply, 

 such a doctrine does not lead to scepticism, but quite the reverse ; 

 we cannot help believing: and the negative reason why we believe 

 is very often because we cannot help it: we can no more help 

 believing than we can help feeling: evidence is related with 

 credibility just as the causes of sensation are with sensibility; the 

 necessary effect of the relation in one case is to produce unavoid- 

 able belief, as it is in the other to produce unavoidable sensation. 

 If the relation is frustrated, then indeed neither effect takes place; 

 and a certain belief is no more producible by certain evidence on 

 a deranged understanding, than the usual sensations are producible 

 by certain excitants in the seat of a modified or impaired sensibility. 



22. The modes by which we acquire a belief are three: by 

 an impression on the senses, by recollection, by inference. Belief, 

 or truths, simply of memory, are not produced by a present im- 

 pression upon the senses, or by analogy ; they are merely the 

 recollection of former witnessings, and never produce belief of 

 present existence. But the events or circumstances which are 

 thus furnished by memory, may become the basis of an inference 

 of a present existence. Thus it is a simple act of memory to 

 inform me that my father was alive when I was last at his house, it is 

 an inference that he is alive now; I recollect that he was alive, but I 

 cannot recollect that he is alive, although I conclude it by a process 

 in which this recollection is concerned. I do not think it necessary 

 to say any more about the evidence of memory, except that in 

 point of force it is, when clear and unequivocal, equal to that which 

 produced the belief which memory renews, and which might have 

 been the result either of aniropression on the senses or of an inference. 



