John Locke

“ The necessity of believing without knowledge, nay often upon very slight grounds, in this fleeting state of action and blindness we are in, should make us more busy and careful to inform ourselves than constrain others. At least, those who have not thoroughly examined to the bottom all their own tenets, must confess they are unfit to prescribe to others ; and are unreasonable in imposing that as truth on other men’s belief, which they themselves have not searched into, nor weighed the arguments of probability, on which they should receive or reject it. ”

“ Probability is either of sensible matter of fact, capable of human testimony, or of what is beyond the evidence of our senses. But to return to the grounds of assent, and the several degrees of it, we are to take notice, that the propositions we receive upon inducements of probability are of two sorts : either concerning some particular existence, or, as it is usually termed, matter of fact, which, falling under observation, is capable of human testimony ”

“ Experience and testimonies clashing infinitely vary the degrees of probability. Thus far the matter goes easy enough. Probability upon such grounds carries so much evidence with it, that it naturally determines the judgment, and leaves us as little liberty to believe or disbelieve, as a demonstration does, whether we will know, or be ignorant. ”

“ The first, therefore, and highest degree of probability, is, when the general consent of all men, in all ages, as far as it can be known, concurs with a man’s constant and never-failing experience in like cases, to confirm the truth of any particular matter of fact attested by fair witnesses : such are all the stated constitutions and properties of bodies, and the regular proceedings of causes and effects in the ordinary course of nature. ”

“ Though the common experience and the ordinary course of things have justly a mighty influence on the minds of men, to make them give or refuse credit to anything proposed to their belief ; yet there is one case, wherein the strangeness of the fact lessens not the assent to a fair testimony given of it. For where such supernatural events are suitable to ends aimed at by Him who has the power to change the course of nature, there, under such circumstances, that may be the fitter to procure belief, by how much the more they are beyond or contrary to ordinary observation. ”

“ 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 ? that 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. ”

“ Analogy in these matters is the only help we have, and it is from that alone we draw all our grounds of probability. Thus, observing that the bare rubbing of two bodies violently one upon another, produces heat, and very often fire itself, we have reason to think, that what we call heat and fire consists in a violent agitation of the imperceptible minute parts of the burning matter. ”

“ We should do well to commiserate our mutual ignorance, and endeavour to remove it in all the gentle and fair ways of information ; and not instantly treat others ill, as obstinate and perverse, because they will not renounce their own, and receive our opinions, or at least those we would force upon them, when it is more than probable that we are no less obstinate in not embracing some of theirs. For where is the man that has incontestable evidence of the truth of all that he holds, or of the falsehood of all he condemns ”

“ In things which sense cannot discover, analogy is the great rule of probability. [Secondly] , The probabilities we have hitherto mentioned are only such as concern matter of fact, and such things as are capable of observation and testimony. There remains that other sort, concerning which men entertain opinions with variety of assent, though the things be such, that falling not under the reach of our senses, they are not capable of testimony. ”

“ For what our own and other men’s constant observation has found always to be after the same manner, that we with reason conclude to be the effect of steady and regular causes ; though they come not within the reach of our knowledge. Thus, That fire warmed a man, made lead fluid, and changes the colour or consistency in wood or charcoal ; that iron sunk in water, and swam in quicksilver : these and the like propositions about particular facts, being agreeable to our constant experience, as often as we have to do with these matters ”

“ This, though in the nature of the thing there be nothing for nor against it, yet being related by historians of credit, and contradicted by no one writer, a man cannot avoid believing it, and can as little doubt of it as he does of the being and actions of his own acquaintance, whereof he himself is a witness. ”

“ I cannot but own, that men’s sticking to their past judgment, and adhering firmly to conclusions formerly made, is often the cause of great obstinacy in error and 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. ”

“ It is a hard matter to say where sensible and rational begin, and where insensible and irrational end : and who is there quick-sighted enough to determine precisely which is the lowest species of living things, and which the first of those which have no life ? ”

“ 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 ”

“ Passion, interest, inadvertency, mistake of his meaning, and a thousand odd reasons, or capricios, men’s minds are acted by, (impossible to be discovered,) may make one man quote another man’s words or meaning wrong. He that has but ever so little examined the citations of writers, cannot doubt how little credit the quotations deserve, where the originals are wanting ; and consequently how much less quotations of quotations can be relied on. This is certain, that what in one age was affirmed upon slight grounds, can never after come to be more valid in future ages by being often repeated. ”

“ And if he be one who takes his opinions upon trust, how can we imagine that he should renounce those tenets which time and custom have so settled in his mind, that he thinks them self-evident, and of an unquestionable certainty ; or which he takes to be impressions he has received from God himself, or from men sent by him ? How can we expect, I say, that opinions thus settled should be given up to the arguments or authority of a stranger or adversary, especially if there be any suspicion of interest or design, as there never fails to be, where men find themselves ill treated ? ”

“ The difference is exceeding great between some men and some animals : but if we will compare the understanding and abilities of some men and some brutes, we shall find so little difference, that it will be hard to say, that that of the man is either clearer or larger. Observing, I say, such gradual and gentle descents downwards in those parts of the creation that are beneath man, the rule of analogy may make it probable, that it is so also in things above us and our observation ”

“ Those who have fairly and truly examined, and are thereby got past doubt in all the doctrines they profess and govern themselves by, would have a juster pretence to require others to follow them : but these are so few in number, and find so little reason to be magisterial in their opinions, that nothing insolent and imperious is to be expected from them : and there is reason to think, that, if men were better instructed themselves, they would be less imposing on others. ”

“ 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. The right use of it, mutual charity and forbearance, in a necessary diversity of opinions. Since, therefore, it is unavoidable to the greatest part of men, if not all, to have several opinions, without certain and indubitable proofs of their truth ”

“ These cannot always be actually in view ; and then we must content ourselves with the remembrance that we once saw ground for such a degree of assent. This is all that the greatest part of men are capable of doing, in regulating their opinions and judgments ; unless a man will exact of them, either to retain distinctly in their memories all the proofs concerning any probable truth, and that too, in the same order, and regular deduction of consequences in which they have formerly placed or seen them ”

“ Fair testimony, and the nature of the thing indifferent, produce unavoidable assent. III. In things that happen indifferently, as that a bird should fly this or that way ; that it should thunder on a man’s right or left hand, &c., when any particular matter of fact is vouched by the concurrent testimony of unsuspected witnesses, there our assent is also unavoidable. ”

“ These probabilities rise so near to certainty, that they govern our thoughts as absolutely, and influence all our actions as fully, as the most evident demonstration ; and in what concerns us we make little or no difference between them and certain knowledge. ”

“ 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. ”

“ 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 anew in so much pains, it is but what we often do ourselves in the like case ”

“ The existence, nature and operations of finite immaterial beings without us ; as spirits, angels, devils, &c. Or the existence of material beings which, either for their smallness in themselves or remoteness from us, our senses cannot take notice of – as, whether there be any plants, animals, and intelligent inhabitants in the planets, and other mansions of the vast universe. ”

“ For these and the like, coming not within the scrutiny of human senses, cannot be examined by them, or be attested by anybody ; and therefore can appear more or less probable, only as they more or less agree to truths that are established in our minds, and as they hold proportion to other parts of our knowledge and observation. ”

“ These are liable to so great variety of contrary observations, circumstances, reports, different qualifications, tempers, designs, oversights, &c., of the reporters, that it is impossible to reduce to precise rules the various degrees wherein men give their assent. This only may be said in general, That as the arguments and proofs pro and con, upon due examination, nicely weighing every particular circumstance, shall to any one appear, upon the whole matter, in a greater or less degree to preponderate on either side ”

“ Things, as far as we can observe, lessen and augment, as the quantity does in a regular cone ; where, though there be a manifest odds betwixt the bigness of the diameter at a remote distance, yet the difference between the upper and under, where they touch one another, is hardly discernible. ”

“ Concerning the manner of operation in most parts of the works of nature : wherein, though we see the sensible effects, yet their causes are unknown, and we perceive not the ways and manner how they are produced. We see animals are generated, nourished, and move ”