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9 4. Probability then, being to supply The grounds the defect of our knowledge, and to guide of probabius where that fails, is always conversant lity are two; about propositions, whereof we have no cer- conformity
with ourown tainty, but only some inducements to re
experience, ceive them for true. The grounds of it are, or the testiin short, these two following. First, the conformity of any thing with others expe«
rience. our own knowledge, observation, and experience.
Secondly, the testimony of others, vouching their observation and experience. In the testimony of others, is to be considered, 1. The number. 2. The integrity. 3. The skill of the witnesses. 4. The design of the author, where it is a testimony out of a book cited. 5. The consistency of the parts, and circumstances of the relation. 6. Contrary testimonies.
§ 5. Probability wanting that intuitive In this all evidence, which infallibly determines the the arguunderstanding, and produces certain know- ments pro ledge, the mind, if it would proceed ration, and con ally, ought to examine all the grounds of ought to be probability) and see how they make more or fore we come less for or against any proposition, before to a judgit assents to, or dissents from it; and upon a due balancing the whole, reject, or receive it, with a more or less firm assent, proportionally to the preponderancy of the greater grounds of probability on one side or the other. For example:
If I myself see a man walk on the ice, it is past probability; it is knowledge; but if another tells me he saw a man in England, in the midst of a sharp winter, walk upon water hardened with cold; this has so great conformity with what is usually observed to happen, that I am disposed by the nature of the thing itself to assent to it, unless some manifest suspicion attend the relation of that matter of fact. But if the same thing be told to one born between the tropics, who never saw nor heard of any such thing before, there the whole probability relies on testimony: and as the relators are more in number, and of more credit, and have no interest to
speak contrary to the truth; so that matter of fact is like to find more or less belief. Though to a man whose experience has always been quite contrary, and who has never heard of any thing like it, the most untainted credit of a witness will scarce be able to find belief. As it happened to a Dutch ambassador, who entertaining the King of Siam with the particularities of Holland, which he was inquisitive after, amongst other things told him, that the water in his country would sometimes, in cold weather, be so hard, that men walked upon it, and that it would bear an elephant if he were there. To which the king replied, “ Hitherto I have believed “ the strange things you have told me, because I look
upon you as a sober fairman, but now I am sure you
lye.” They being
9 6. Upon these grounds depends the capable of probability of any proposition : and as the great va- conformity of our knowledge, as the certainriety,
ty of observations, as the frequency and constancy of experience, and the number and credibility of testimonies, do more or less agree or disagree with it, so is any proposition in itself more or less probable. There is another, I confess, which though by itself it be no true ground of probability, yet is often made use of for one, by which men most commonly regulate their assent, and upon which they pin their faith more than any thing else, and that is the opinion of others : though there cannot be a more dangerous thing to rely on, nor more likely to mislead one; since there is much more falsehood and errour among men, than truth and knowledge. And if the opinions and persuasions of others, whom we know and think well of, be a ground of assent, men have reason to be Heathens in Japan, Mahometans in Turkey, Papists in Spain, Protestants in England, and Lutherans in Sweden. But of this wrong ground of assent I shall have occasion to speak more at large in another place.
Of the Degrees of Assent.
). The grounds of probability we have Our assent laid down in the foregoing chapter ; as they ought to be are the foundations on which our assent is regulated by
the grounds built, so are they also the measure whereby of probabiliits several degrees are, or ought to be regu- ty. lated : only we are to take notice, that whatever grounds of probability there may be, they yet operate no farther on the mind, which searches after truth, and endeavours to judge right, than they appear; at least in the first judgment or search that the mind makes. I con. fess, in the opinions men have, and firmly stick to, in the world, their assent is not always from an actual view of the reasons that at first prevailed with them: it being in many cases almost impossible, and in most very hard, even for those who have very admirable memories, to retain all the proofs, which upon a due examination made them embrace that side of the question. It suffices that they have once with care and fairness sifted the matter as far as they could; and that they have searched into all the particulars, that they could imagine to give any light to the question : and with the best of their skill cast up the account upon the whole evidence; and thus having once found on which side the probability appeared to them, after as full and exact an enquiry as they can make, they lay up the conclusion in their memories, as a truth they have discovered; and for the future they remain satisfied with the testimony of their memories, that this is the opinion, that by the proofs they have once seen of it deserves such a degree of their assent as they afford it.
§ 2. This is all that the greatest part of These cannot men are capable of doing, in regulating always be their opinions and judgments; unless a man actually in will exact of them, either to retain distinctly view, and
then wemust. in their memories all the proofs concerning
content our- any probable truth, and that too in the same selves with order, and regular deduction of consequences the remem- in which they have formerly placed or seen we once saw them; which sometimes is enough to fill a ground for large volume on one single question : or else such adegree they must require a man, for every opinion
that he embraces, every day to examine the proofs: both which are impossible. It is unavoidable therefore that the memory be relied on in the case, and that men be persuaded of several opinions, whereof the proofs are not actually in their thoughts; nay, which perhaps they are not able actually to recal. Without this the greatest part of men must be either very sceptics, or change every moment, and yield themselves up to whoever, having lately studied the question, offers them arguments; which, for want of memory, they are not able presently to answer. The ill con- 3. I cannot but own, that men's sticksequence of ing to their past judgment, and adhering this, if our former judg
firmly to conclusions formerly made, is often ments were the cause of great obstinacy in errour and not rightly mistake. But the fault is not that they rely
on their memories for what they have before well judged; but because they judged before they had well examined. May we not find a great number (not to say the greatest part) of men that think they have formed right judgments of several matters; and that for no other reason, but because they never thought otherwise? who imagine themselves to have judged right, only because they never questioned, never examined their own opinions? Which is indeed to think they judged right, because they never judged at all : and yet these of all men hold their opinions with the greatest stiffness; those being generally the most fierce and firm in their tenets, who have least examined them. What we once know, we are certain is so: and we may be secure, that there are no latent proofs undiscovered, which may overturn our knowledge, or bring it in doubt. But, in matters of probability, it is not in every case we can be
sure that we have all the particulars before us, that any way concern the question ; and that there is no
evidence behind, and yet unseen, which may cast the probability on the other side, and outweigh all that at present seems to preponderate with us. Who almost is there that hath the leisure, patience, and means, to collect together all the proofs concerning most of the opinions he has, so as safely to conclude that he hath a clear and full view; and that there is no more to be alleged for his better information ? And yet we are forced to determine ourselves on the one side or other. The conduct of our lives, and the management of our great concerns, will not bear delay: for those depend, for the most part, on the determination of our judgment in points wherein we are not capable of certain and demonstrative knowledge, and wherein it is necessary for us to embrace the one side or the other. 4. Since therefore it is unavoidable to
The right the greatest part of men, if not all, to have use of it, is several opinions, without certain and indubi- mutual chan table proofs of their truth; and it carries too pity and for
bearance. great an imputation of ignorance, lightness, or folly, for men to quit and renounce their former te. nets presently upon the offer of an argument, which they cannot immediately answer, and show the insuffi, ciency of: it would methinks become all men to maintain peace, and the common offices of humanity and friendship, in the diversity of opinions : since we cannot reasonably expect, that any one should readily and obsequiously quit his own opinion, and embrace ours with a blind resignation to an authority, which the understanding of man acknowledges not. For however it may often mistake, it can own no other guide but reason, nor blindly submit to the will and dictates of another. If he, you would bring over to your sentiments, be one that examines before he assents, you must give him leave at his leisure to go over the account again, and, recalling what is out of his mind, examine all the particulars, to see on which side the advantage lies ; and if he will not think our arguments of weight enough to engage him a-new in so much pains, it is but what we often do ourselves in the like case ; and we should take it amiss if others should prescribe to us what points we