Front Page Titles (by Subject) CHAPTER VI.: DEGREES OF PERSUASION AND PROBATIVE FORCE, HOW MEASURED. - The Works of Jeremy Bentham, vol. 6
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CHAPTER VI.: DEGREES OF PERSUASION AND PROBATIVE FORCE, HOW MEASURED. - Jeremy Bentham, The Works of Jeremy Bentham, vol. 6 
The Works of Jeremy Bentham, published under the Superintendence of his Executor, John Bowring (Edinburgh: William Tait, 1838-1843). 11 vols. Vol. 6.
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DEGREES OF PERSUASION AND PROBATIVE FORCE, HOW MEASURED.
Importance of a correct form for expressing degrees of persuasion and probative force.
Persuasion admits of, and exists in, different degrees of strength, different degrees of intensity; for strength, force, and intensity, are here synonymous.
Of these differences, the practice of wagering affords at the same time a proof of the existence, and a mode of expression or measurement for the quantities or degrees: in which latter character it will claim, farther on, a more particular notice.
Another matter of fact not less notorious is, that by these theoretical differences and supposed degrees of difference, in whatever mode and with whatever degree of accuracy expressed and measured, human conduct is on a variety of occasions governed: instance once more the practice of wagering, and the various applications of the principles of insurance grounded on it.
Not only the persuasion of an ordinary man on an ordinary occasion, but the persuasion of a judge on a judicial occasion, is capable of existing in different degrees of strength.
Whenever a fact comes in dispute, the belief of which on the part of the judge is necessary to produce and warrant such a decision as shall give effect to a right, the first object aimed at by the legislator ought to be, as already stated, so to order matters, that evidence of the highest possible degree of probative force in proof of that fact, shall be forthcoming: the next object, that the judge may always form the same estimate of the probative force of the evidence, as the legislator would do if it were possible for him to take an estimate of it.
But every element of judicature is subject to variation in quantity and degree.
In the case of circumstantial evidence, the probative force of the evidentiary fact, considered as indicative of the existence of the principal fact (which is as much as to say the strength of the persuasion produced by it,) is susceptible of every variety of degree in the bosom of the judge.
In the case of immediate testimonial evidence (setting aside the consideration of any supposed improbability of the fact stated, and any supposed imperfection in the disposition and character of the witness,) the strength of persuasion on the part of the judge will be as the strength of the persuasion expressed on the part of the witness: which is, in other words, to say,—the probative force of the testimony delivered by the witness will be exactly as, or rather will be the same thing with, the strength of the persuasion expressed by him in the delivery of it.
The strength of the persuasion expressed by the witness will, if clear of wilful falsehood, be (in so far as the means of discourse at his command admit of correctness) exactly the same in degree with the strength of the persuasion actually felt and entertained by him at the time.
But the strength of the persuasion so entertained by him is subject to be diminished in any degree by each of two causes: viz. 1. By weakness on the part of his percipient faculty, i. e. want of clearness and distinctness on the part of the conception formed of the fact at the time; 2. By weakness on the part of his retentive faculty—want of strength and distinctness on the part of the impression made on the memory by the firstformed conception.
Of incorrectness in one quarter, error and consequent misdecision in another is thus a natural result.
If, on comparing together the testimonies delivered by a number of witnesses—say by three witnesses—it appears to the judge that they joined, all of them, in regarding the existence of the fact as more probable than the non-existence of it; whereas, in truth, the force of the persuasion, when thus compounded together, lay not on that side: here an instance of misdecision will have taken place on the part of the judge; and no worse could have happened, had these testimonies been none of them forthcoming, or had they all, after joining in a tale of wilful falsehood, obtained credence for it as if it had been true.
In what has been already said, reason will probably be seen for regarding a correct mode of expressing degrees of persuasion and probative force as an object of no inconsiderable importance; and the further we go into the examination of the subject, the clearer will be the light in which the importance of it will present itself.
Unfortunately, the language current among the body of the people is, in this particular, most deplorably defective:—I know—I believe:—the fact happened so and so—I believe it happened so and so: and there the gradation ends.
Among men of law, to whichsoever of the two great schools of law belonging, nothing better is to be found.
The language of mathematicians will be seen to afford two different modes or principles.
One is perfectly correct: it is the mode of expression used in speaking of the doctrine of chances. But unfortunately it will be found not applicable to the present purpose.
Another, as applied to the present purpose, will be found incorrect. It is that which, assuming the greatest possible quantity to be a finite quantity, proceeds to divide it into parts; as a circle, which, how small soever, constitutes a whole, has, according to the usage of mathematicians, been divided into 360 degrees. Happily, incorrect as it is, its incorrectness will not be found attended with any practical inconvenience; since, on each occasion, whatever degree of correctness can on that occasion be of any use, can always be attained.
In truth, between infinite and finite, there is no medium; between the one mode and the other, there is accordingly no alternative. Of that mode which considers the greatest possible degree of probative force as being (what it really is) an infinite quantity, it will be seen that it is altogether inapplicable to the purpose of judicial decision: there remains, therefore, as the only mode applicable, that which considers it as a finite quantity, having the number of its parts limited and determinate.
Suppose a number of witnesses deposing to the principal fact in question, in the way of direct evidence—there being no need of any such inference as has a necessary place in the case of circumstantial evidence; and suppose, moreover, that no doubt has place in the mind of the judge respecting the character and disposition of any of those witnesses; whatsoever be the aggregate force of persuasion entertained by all those witnesses put together, such, of course, will be the strength of persuasion on the part of the judge.
Conceive the possible degrees of persuasion, positive and negative together, to be thus expressed:—
The degrees of positive persuasion—persuasion affirming the existence of the fact in question—constitute one part of the scale; which call the positive part.
The degrees of negative persuasion—persuasion disaffirming or denying the existence of the same fact—constitute the other part of the scale; which call the negative part.
Each part is divided into the same number of degrees: suppose ten, for ordinary use. Should the occasion present a demand for any ulterior degree of accuracy, any degree that can be required may be produced at pleasure, here, as in other ordinary applications of arithmetic, by multiplying this ordinary number of degrees in both parts by any number, so it be the same in both cases: the number ten will be found the most convenient multiplier. In this case, instead of 10, the number of degrees on each scale will be 100, or 1000, and so on.
At the bottom of each part of the scale stands 0; by which is denoted the non-existence of any degree of persuasion on either side—the state which the mind is in, in the case in which the affirmative and the negative, the existence and the non-existence of the fact in question, present themselves to it, as being exactly as probable the one as the other.
Such is the simplicity of this mode of expression, that no material image representative of a scale seems necessary to the employment of it.
The scale being understood to be composed of ten degrees—in the language applied by the French natural philosophers to thermometers, a decigrade scale—a man says, My persuasion is at 10 or 9, &c. affirmative, or at 10 or 9, &c. negative: as, in speaking of temperature as indicated by a thermometer on the principle of Fahrenheit, a man says, the mercury stood at 10 above, or at 10 below, 0.
If ulterior accuracy be regarded as worth pursuing, to the decigrade substitute (giving notice) a centigrade scale; and if that be not yet sufficient, a milligrade.
Three persons make their appearance in the character of witnesses in relation to the existence of the same fact: an option is given to them of three declarations, of which, one or other, in the instance of each witness, it is evident cannot but be true; viz. 1. I believe the fact exists;—2. I believe the fact does not exist;—3. I am unable to form any belief concerning the fact, whether it does exist or does not. Being asked, each of them, what number of degrees in the scale comes nearest to expressing the strength of his persuasion, it being, as already declared by each, on the affirmative side; they answer by indicating, each of them, the same number—number 1.
In these three instances, the force of persuasion is at the least amount at which it can stand on either side.
Take now, in relation to the same fact, two other witnesses; and in the instance of each of them, let the force of persuasion be at its maximum, represented as above by the number 10.
Of these two witnesses, the persuasion may be on the same side as that of the three witnesses; or it may be on the opposite side.
Suppose it on the opposite side, viz. the negative. Out of 30 degrees of persuasion which the three witnesses might have had, they have but 3; while of the 20, the utmost number which the two were capable of having between them, they have the whole.
Observe now the variation which the decision of the judge must experience, according as he has or has not the means of hearing and noting down the differences which are in every instance liable to have place in regard to the quantum of persuasion on the part of witnesses.
It, as hitherto, these differences are unascertainable (the indications afforded by character and by probability being by the supposition out of the question,) the judge can do no otherwise than decide according to the number of the witnesses—according to the difference between the numbers on each side, his decision will be—the fact does exist.
If, being ascertainable, these differences are ascertained, as above,—the force of persuasion on the part of the witnesses on both sides taken together, being now his guide, and beyond dispute his proper guide, his decision will be—the fact does not exist.
Thus much as to the station of witness: let us come now to the station of judge.
Casual modifications apart, the persuasion of the judge has for its efficient cause, the persuasion of the witness persuasion on the part of the public at large has for its efficient cause, the persuasion of the judge.
But among three, and even as far as nineteen witnesses, in relation to the same point, the aggregate force of persuasion, it may easily happen, shall be less than among two witnesses.
In like manner among three, and even as far as nineteen judges, in relation to the same point, the aggregate force of persuasion may be less than of two other judges.
For want of an adequate mode of expression, the real force of testimony in a cause has hitherto been exposed to perpetual misrepresentations.
For want of an adequate mode of expression, the real force of judicial opinion and authority in a cause has in like manner been hitherto exposed to similar misrepresentations.*
Of a scale of this sort, supposing the use of it allowed, five things, it should seem, might be predicated, viz.—
1. That when employed, it would be employed without confusion, difficulty, vexation, or other inconvenience in any shape.
2. That, at first more especially, it would not however be in frequent use.
3. That by degrees, as the human understanding improved, the use of it would become more and more frequent.
4. But that at no time would the number of occasions calling for it (i. e. the number of the occasions on which, for the purpose of giving a correct expression to the degree of persuasion felt by him, the individual felt the need of such an instrument) be very considerable.
5. That the greater the importance of the cause, the more likely would the instrument be to be called into use.
Being altogether optional, all possibility of vexation is by that circumstance excluded from the use of it.
Everything of difficulty and confusion stands equally excluded, a man will not call for the scale unless he knows perfectly well how to use it—and it seems not easy for a man not to know. If he makes no use of the scale, the effect of his testimony or his suffrage is as if he had placed the index at No. 10, the highest degree in the scale: if it be his desire to make use of the scale, he places the index at No. 9, or any lower number, as he pleases.
The use of it, says the third observation would be gradually more and more frequent.
Increased correctness, in effect, is the natural result of increase of attention: in proportion as the attention of man fixes itself closer and closer to any subject, advancement in science, as well as increased correctness in art and practice, gradually creep on. It is by increased closeness of attention that discoveries are made, and advances effected, in every path of art and science.
Old measures of every kind receive additional correctness; new ones are added to the number, the electrometer, calorimeter, the photometer, the eudiometer, not to mention so many others, are all of them so many productions of this age. Has not justice its use, as well as gas?†
Application of the principle to different cases in Judicature.
Strength of persuasion belongs to that class of facts which has already been distinguished by the name of psychological facts.* Among the properties of the facts of this description, is that of not being indicated by direct testimony, other than that of the one individual in question: under that exception, not being indicated by other than circumstantial evidence.
Of a persuasion on the one side or the other, the declaration has on various occasions been rendered matter of obligation in legal practice. But as to the force or degree of persuasion, no distinction having ever been called for on any occasion, so accordingly not on this.
The fact of the existence of a persuasion on the affirmative side, or on the negative, has been considered as being, when untrue, susceptible of being disproved; and so thoroughly susceptible, that, in case of falsity, such falsity has been deemed, and in practice constituted, a ground for punishment. In every instance of the crimen falsi—in every instance in which falsehood, howsoever expressed, whether by discourse or by deportment, enters into the composition of the offence—such is the case; for a false assertion is the false declaration of a persuasion in relation to some fact or facts.
On pain of eventual punishment, a man is thus continually called upon to declare persuasion, and punished in the event of his being deemed to have placed it on the wrong side of O [Editor:?]. But even supposing the scale of persuasion in use, it would scarcely for a long time, if ever, be deemed consistent with justice to punish him on the ground of his being deemed to have placed his persuasion at a wrong point on the right side.
In case of adverse interest striving to produce deception, there appears therefore but little if any hope, that any considerable beneficial effect could be produced by an instrument of expression, the use of which is, in the respect in question, to put the means of correct expression in men’s hands.
But, happily, instances are by no means wanting in which interest is neuter; insomuch that, whatsoever be the real force of a man’s persuasion, it would be on the score of interest not disagreeable, and on the score of love of justice, and other social affections, positively agreeable, to make declaration of that in preference to every other.
In the intercourse of life, and for self-regarding purposes, nothing (as hath been already intimated) is more common than for men to give expression to the force of their persuasion, and upon a principle closely analogous, to the utmost nicety. Wagering in all its forms, whether in the way of sport or in the way of business, under the guidance of forecasting prudence, has already been mentioned in this view.
Under the influence of a principle of action comparatively so faint, in the greater number of minds, as the love of justice, or any other modification of the social principle, equal correctness cannot reasonably be expected, since attention equally close cannot reasonably be expected. But, that everything that could be wished cannot be obtained, is no reason why that which can be obtained, should, if useful, be neglected; and by the help of a scale of persuasion, as here brought to view, it is easy to see how high a degree of correctness might be attained in this particular, in comparison of everything that has been as yet exemplified.
Apply it first to the case of a witness.
At present, when a witness has delivered his evidence, if stated in a simple manner, without any expression of doubt, it is understood of course as being at its maximum. But it any doubt or diffidence—anything tending, as supposed, to call upon the judge to make any defalcation from that maximum, is manifested, the subject is thereby thrown into a sort of confusion, in the midst of which, the language in use not affording a clue, the judge acts according to the humour or interest of the moment; and as the interest of the moment never fails to urge dispatch, chance, at the best, shares the decision of the cause with justice.
In the use of the instrument by which the point in the scale of persuasion is fixed, there need not be any greater difficulty than in the use of the dial-plate of a clock or watch, or the instruments respectively employed for reckoning at a game at billiards or a game at cribbage.
If the importance of the cause appear such as to pay for this small portion of vexation and delay, the persuasive scale is presented to the witness, with liberty and discretion to place the index either at the highest point, it that be considered as the ordinary one, or at any inferior point by which, according to his own conception, the force of his persuasion may be more accurately designated.
Apply it now to the station of judge.
In this commanding station, men are without difficulty considered as exempt from, or proof against, the action of all sinister interest—proof, at any rate, against all temptation to any such mal-practice as that of misrepresenting their own opinions.
No objection, therefore, except to the novelty and utility of it, would, in the instance of judge, stand opposed to the taking a man’s own account for the inward strength of his own persuasion, and reducing the outward effect of it to a conformity with the real state of it so declared.
If the effect of such a liberty were to augment his power, the objections would be insuperable; but a man may, without much danger, he trusted with the faculty of reducing it.
In this case, be it observed, the grant of this faculty need not be confined to the question of fact: the import, or state, of the law (the import of it if in the form of statute law, the state of it if in the form of judge-made law) constitutes a no less proper subject of persuasion—in a word, a no less proper subject of opinion—than the question of fact.
Under this general head, a variety of particular cases will exemplify the utility of this instrument of accurate judicature.
Case 1. Judges divers, and the number equally divided.—In this case, the supposition acted upon is, that on the part of every one of them, the force of persuasion was at the same pitch—on the part of each of them, at its maximum. The instrument employed, it would turn out, perhaps, that in each of them the force of persuasion was different; on one side or other an aggregate force of persuasion clearly preponderant.*
Case 2. Appeal.—The decision become the subject of an appeal to an ulterior judicatory.
Not unfrequent are the occasions on which the real aggregate force of persuasion on the part of the original judicatory may, on just grounds, be taken into consideration by the ulterior judicatory. Suppose, for example, a question of fact, and evidence thereupon delivered vivâ voce. In some cases, the testimony of the witness cannot be received in the oral form on any terms by the ulterior judicatory: at any rate, by the repetition, the colour of the evidence, especially so much as is afforded by deportment,† is liable to be changed. To be informed of the impression made on the original judicatory by the same testimony, and in its freshest state, might on such an occasion be of considerable use.
Case 3. Pardon. In a penal case, the judgment being a judgment of conviction, a question proposed is, whether the power of the sovereign shall be applied to the remission of it.
Among the most justifiable causes for the exercise of this power, is a doubt whether the defendant, who has been deemed guilty as above, was really so.
Sometimes the cause of such doubt is to be found in some article of information subsequently brought to light, and, in the character of evidence, sufficiently established for this purpose. But at other times, the doubt has for its cause a doubt on the part of the judicatory: on the part of some judge or judges, the persuasion entertained of the delinquency of the defendant not being at so high a pitch as, to warrant an operation to such a degree afflictive, it is conceived it ought to be. Pardon or no pardon turning in this case upon the degree of persuasion on the part of each member of the judicatory, the importance of accuracy in the expression given to those several degrees is sufficiently manitest.
Even although the principle of judging from the aggregate of persuasion, instead of the number of persons persuaded, should not be adopted for judicial decision, it might for pardon.
Case 4. The same question moved elsewhere, in another judicatory and in another cause.
So far as concerns the question of fact,—unless where, being considered as having received a decision in the antecedent judicatory, that decision is considered as conclusive,—the opinion of the members of any such antecedent judicatory is not usually taken for an object of regard.
But in so far as any question of law is concerned, great anxiety is commonly testified to learn with the utmost correctness the degree of persuasion entertained in such antecedent judicatory, supposing it not subordinate with relation to the judicatory now in question.
Case 5. Punishment or satisfaction to be administered pro modo probationum.
A topic this, which, though it be in the Roman school, and in particular in the French form of that school, that it has received a name, is in practice not altogether disregarded in the English school. Various are the instances in which a degree of probative force, which would not be considered as sufficient to warrant conviction for the purpose of punishment, is considered, and not without reason, as sufficient to warrant a decision by which satisfaction in some shape or other is awarded. The only expression that can be given by a judge to the conception entertained by him of the degree of probative force appertaining to the evidence, being a declaration of the degree of strength of the persuasion of which it has been productive, it seems sufficiently obvious how material it is to this purpose, that a mode of expression the most correct that the nature of the case admits of, should on this occasion be capable of being employed.
Case 6. Scientific evidence.—Scientific is the denomination that, for distinction’s sake, may be given to the judicial declaration of a species of functionary, in whose function the character of judge is in some sort combined with that of witness. It comes to be exercised as often as—for the guidance of the opinion of the regular judge in relation to some matter of fact, a just conception of which is considered as requiring some particular skill, such as falls not to the lot of all members of the community, nor in particular, unless by accident, to the lot of the regular judge,—the opinion of a person considered as being in an adequate degree possessed of the species of skill in question, is called in.
In the Roman school, this species of functionary is named by the judge, and treated on the footing of a sort of judicial officer acting under the judge.
In the English school, he is named by the party to whom it occurs to expect that an opinion extracted from that source will be serviceable to his side of the cause; and is treated on the footing of any other witness.
On whatever footing his opinion, in other words his persuasion, in relation to the matter of fact in question, is called in, it cannot be matter of doubt how beneficial it cannot but be to the interests of justice, that the means should be in his hands for giving to the expression of the degree of force of his persuasion whatsoever degree of accuracy he thinks fit.
Incapacity of ordinary language for expressing degrees of persuasion and probative force.
Such, as above brought to view, are the advantages deducible from an adequate mode of expressing degrees of persuasion and probative force, supposing it to be found. If the current language were adequate to this purpose, there would be no need to look out for any other. That to this hour it remains as far from being so as it is possible for it to be, is perceived upon a general view at the first hint. But, by a particular observation or two, the nature of this penury may be rendered more distinctly perceptible.
In a word, the only adequate mode of expressing degrees of persuasion is by numbers. But hitherto, neither in ordinary language, nor in the scientific language of jurisprudence, have numbers been employed. The result, in point of imperfection and inadequacy, will be conspicuous.
Persuasion, the only term equally proper in all cases—that is, in all degrees—is accordingly the term that has all along been employed here.
Opinion, though in some cases capable of taking its place, is not synonymous with it; since opinion is scarcely considered as being, like persuasion, susceptible of degrees.
In addition to this term, which, comparatively speaking, is not in very frequent use, come two others, both of them in perpetual use, viz. knowledge and belief.
In ordinary discourse, applied to ordinary topics, the word belief seems to be applied to designate any degree of persuasion; and accordingly it cannot be employed to designate any one, to the exclusion of any other.
Among religionists, applied to the topic of religion, it is employed to designate the very highest degree, and to the exclusion of every other; since it is not any inferior degree that will satisfy them.
Among lawyers, on the contrary—to wit, among English lawyers, it has been employed to designate any inferior degree of persuasion, to the exclusion of the highest.
For giving expression to the highest, what they have declared themselves to expect, is, that a witness shall either employ the forms of naked assertion—such a thing is so and so—or introduce the word knowledge. Belief, in certain cases, they have admitted of, recognising it as designative of an inferior degree of persuasion; but in other cases, in the character of an expression of the degree of persuasion, nothing will satisfy them but knowledge—a degree of persuasion above belief.
If your persuasion falls short of amounting to belief, the priest, so far as depends upon himself, consigns you to everlasting punishment in a life to come:* if it fails of mounting above belief, the man of law, the judge, consigns you, and in a manner more visibly efficient, to punishment in the present life.†
Knowledge, with its logical conjugates, comprising the verb to know, not only expresses the highest degree of persuasion possible, but in some circumstances expresses that highest degree of persuasion as existing in two different minds at a time. If I say—I know that London lies to the north of Paris. I speak of my own persuasion only; but if I say—You know that London lies to the north of Paris. I speak of my own persuasion as well as yours—of yours alone expressly, but of my own by implication, and that a necessary one; for were my persuasion on the subject short of the highest point, the expression would be a contradiction in terms.
In this instance, as in so many others, the indirect mode of assertion has the effect of expressing a stronger degree of persuasion than can be expressed by the direct.‡
In the language of English as well as other lawyers, a case is spoken of as proved—as fully proved. In regard to the state and degree of persuasion, and of the nature of the cause by which, on the part of the judge, it has been produced, what is understood by this expression? Answer: That, the evidence being either direct—or, if circumstantial, of that sort which is commonly received either as an equivalent or as a necessarily receivable substitute to direct—the strength of persuasion expressed by it on the part of the witness is such as (it standing unopposed either by any objection, or at least by any preponderant objection, to the trust-worthiness of the witness, or by any counter-evidence, or at any rate by counter-evidence of preponderant force) will naturally, on the part of the judge, be productive of such a degree of persuasion, in affirmation of the existence of the fact in question, as shall be sufficient to authorize and require a decision on that side.
In speaking of evidence as having been delivered in relation to the fact in question,—suppose an occasion to arise for avoiding to pronounce decidedly concerning the direction or strength of the persuasion of which it may have been productive: in this case, instead of speaking of the fact as having been proved, the usage is to speak of it as having been attested, affirmed, or denied, in or by deposition or evidence.
Roman school—its attempts to express degrees of probative force.
The Romanists, in expressing their sense of the importance of giving correctness to the description tendered of the degrees of persuasion entertained in each case, betray, and in a manner confess, their incapacity of finding a solution for the problem thus proposed.
1. Full—2. More than half-full—3. Half-full—4. Less than half-full:—Such, if Heineccius is to be believed, are the degrees of probative force that have been distinguished, and have received denominations, in his school of fraud and nonsense.∥
But of these distinctions the application is continued to the aggregate mass of evidence taken together—the mass produced on one side of the cause. They are not applied either to the force of persuasion on the part of the judge, or so much as to the probative force of the evidence of any one witness when considered by itself.
That they should have had any application to the probative force of the evidence of any witness taken singly, would indeed, according to the notion of that school, have been somewhat difficult: seeing that, according to what, by him, is given as the better opinion, the probative force of the evidence of any one witness, be he who he may, is equal to 0: insomuch that, of the party by whom any such article of evidence has been produced, and no more, the condition ought not to be better than if he had produced none at all.*
In the French form of the Roman school, another scale, of a somewhat different construction, was in use, according to M. Jousse,† in the particular case in which the cause was of that sort which, if decided against the defendant, subjected him to capital punishment, and, by way of preparation for that punishment, to torture.
1. Highest degree of probative force, the degree sufficient to warrant conviction.
2. Next highest, or second degree of probative force, the degree expressed by the words “urgent and indubitable.” The practical effect of this degree of probative force was sufficient to subject him to torture, with power to the judges to subject him to any punishment short of capital, if the torture, the object of which was to prevail upon him to confess whatever he was accused of, failed of producing that desirable effect.
3. Third degree of probative force, the degree expressed by the words less than “most violent.” Practical effect, subjecting him to torture, but without any such power to the judges: the torture having, when the probative force was at this degree, and not above a “purgative” quality, and that of so particular a sort, as to “purge the proofs” (what is meant is probably to purge away the proofs) whatever they may be, that have operated to his prejudice in such manner as to subject him to the torture.
English school—its attempts to express degrees of probative force.
1. Positive proof—2. Violent presumption—3. Probable presumption—4. Light or rash presumption: such are the degrees of probative force that have been distinguished and denominated in the English school.
At the head of this scale, under the appellation of positive proof, is designated direct evidence, however trustworthy the source: below it, circumstantial, however great its force: and to make the distinction so much the clearer, “violent presumption,” we are told, “is many times equal to full proof;”—“probable presumption hath also its due weight;”—“light or rash presumptions have no weight or validity at all.”
The degree of probative force indicated by the light or rash presumption of the English school, is thus exactly equal to that expressed by the half-full proof of the Roman school; each of them being equal to 0.
But the Roman school has risen to a pitch of accuracy by which the English has been left at a distance; the Romanists having a degree of force which is less than equal to 0, and which, though incapable of producing in the breast of the judge any degree of persuasion whatsoever, is still probative force.
The scale thus exhibited is a scale of probative force abstractedly considered—considered without distinction made as to the quantity and composition of the evidence to which the probative force is considered to belong.
It has accordingly no connexion with, or reference to, that other scale above mentioned, which is a scale of persuasion merely, and of which the degrees are two, and but two, expressed by the words knowledge and belief.
No such suspicion appears to have found its way into either of these learned bosoms, as that of a connexion between any such objects as persuasion on the part of a witness, probative force on the part of his testimony, and persuasion on the part of the judge—all susceptible of variation on one and the same scale.
The observation of the connexion between these clearly distinguishable, though so closely connected, objects, was, as far as it goes, an observation in psychology—an observation made of the invariably observable phenomena of human nature; and it is among the characteristics of technical law learning, as of Aristotle’s system of dialectics, in which his system of physics was comprised, to look down with indignant disdain on the invariably observable phenomena of human nature.
In both instances, the notion entertained of science seems to have been that it was confined to words; that it consisted in a perpetual substitution of words to words; and that—in addition to words—ideas, clear and distinct ideas, were no better than an incumbrance
1. Unqualified assertion;—2. Assertion qualified by the words “to his remembrance,” or, “as he believeth:”—such are the forms of speech devised by the Earl of Clarendon when chancellor of England, for expressing two degrees of persuasion, which it seemed necessary to him to distinguish.§
This second or inferior degree of persuasion is the degree which he permitted to be expressed in the case of a defendant interrogated by an instrument called a bill in equity, as to a matter charged as his [the defendant’s] own act, in any other case than “if it be laid to be done within seven years before;” not saying before what, but probably enough meant to designate the day on which the matter of the written instrument met his eye.
But if it be laid to be done within seven years before, then it is that the proposed respondent must (on pain, it should seem, of being punished, if he persists, for contempt, as having put in an insufficient answer) take care not to suffer to stand as part of his answer either of those forbidden forms of speech; “unless the court, upon exception taken, shall find special cause to dispense with so positive an answer.”
The circumstance by which, on this occasion, the attention of this learned person appears to have been engrossed, is the distance in point of time: among the circumstances that appear to have escaped it, are, the importance of the fact (regard being had to the situation and character of the deponent,) the differences of which that importance is susceptible, and the influence of these differences upon the memory. Another consideration, alike overlooked, seems to have been the influence of time of life upon memory, and the difference in this respect between immaturity, maturity, and caducity.
But the faculty of having recourse to the wisdom and justice of the court “upon exception taken,” presented a solution for every difficulty, a remedy for every inconvenience; a faculty which, to the merit of being to the suitor a source of relief, added the much superior, though so little published, merit, of being, to the judge, his friends, and dependents, a source of fees.
On the present occasion, however, the mode of constructing the scale, and giving denomination to the degrees of which it is composed, constitute the proper subjects of consideration: not the application or applications made of them.
“You shall swear that what is contained in this your answer, so far as concerns your own acts and deeds, is true, and that what relates to the acts and deeds of any other person or persons, you believe to be true. So help you God.” (Before commissioners,)—such is the form of the oath at present exacted of a defendant in an equity court, or, at any rate, on the equity side of the court of Exchequer.* Of two things, one: either there is something in the air of the court of Exchequer that strengthens a man’s memory, and relieves it from the need of having recourse to that indulgence which has just been seen to be allowed in the court of Chancery: or the indulgence of the court has been silently withdrawn in practice, while the continuators of Mr. Harrison’s book continue to represent as still in force the regulation by which it was granted.
An infinite scale inapplicable, though the only true one.
In respect of persuasion and probative force—persuasion, in the first place on the part of a witness, in the next place on the part of the judge—probative force on the part of the evidence, of whatsoever nature it be, direct evidence or circumstantial evidence, evidence of persons or evidence of things;—an infinite scale (it has been already intimated) is the only sort of scale by which the truth of the case can be expressed. For what can that mass of evidence be, to the probative force of which no addition is made by the addition of a mass of evidence, exactly of the same composition in every respect, and twice as great?
Unfortunately, a scale to such a degree correct would not, physically speaking, be capable of being applied to the particular purpose here in view.
The use, and only use, of the sort of scale in question, would be to enable the witness to give to his testimony, or the judge to his opinion, a less degree of effect in practice than what it is productive of without the employment of any such scale.
At present, the effect given to any such testimony in practice is as great—never less than as great—as the utmost effect of which the highest possible degree of persuasion in that single breast could be productive. On the side of augmentation, then, nothing remains to be done. The persuasion is considered as being, in every instance, at the highest degree; or at any rate, in practice, the same effect is given to it as if it were.
At the same time, many are the instances in which it may be rendered manifest beyond a doubt, that the degree of persuasion, to which in practice all the effect is given that could be given to the highest, really falls greatly below the highest degree of which the force of persuasion is susceptible.
1. In the case of the witness, this deficiency can scarcely be rendered manifest by any considerations of a nature to operate alike on all minds to whom they are presented: where it exists, it is matter not of demonstration, but of sensation only; viz. on the part of the witness in question, by whom alone the force of the persuasion, of which the seat is in his own mind, can be perceived.
Even the witness, the individual himself whose persuasion is in question,—though his perception may have informed him, that, of two cases, his persuasion has been stronger in the second than in the first; still it is only by calling in the aid of numbers that it will be possible for him to declare, or so much as to settle with himself in his own mind, how much, of numbers, as, for instance, by saying,—in the first case it seems to me that the probability of the fact is as 2 to 1, in the second case as 4 to 1; insomuch that, were it matter of necessity to me to lay a wager on the subject, such and no more are the odds that I would lay or take in the two respective cases.
2. In the case of the judge, on the other hand, the deficiency may be rendered manifest to third persons.
On the subject of a question of fact, deposed to by a number of witnesses—the fact having nothing of improbability in its nature, nor the witnesses anything to distinguish them in point of trustworthiness, nor their testimonies respectively anything to distinguish them in respect of the degree of persuasion manifested—the degree of persuasion on the part of the judge will of course be as the number of the witnesses.
This being the case,—by every witness added on the same side, an additional degree of force will be added to the persuasion of the judge: and if this be true with regard to a second and a third witness, it cannot be otherwise than true with regard to a hundredth or a thousandth.
Long before the number of witnesses has reached to the height of a hundred, the mind of the judge (it may be said) will have obtained all the satisfaction it could desire: long before this, the multitude will have appeared to him so abundantly sufficient, that he will have refused to give admission to any more.
This may, and naturally will be, the case. But should be even have refused admission to all the witnesses after the second, it will be impossible for him to deny but that, after a thousand have been heard, an addition will still be made, by any other such witness, to the aggregate probative force of the whole mass of evidence thus composed. Had he been the only witness, the testimony of this thousandth and first would of itself have been sufficient to determine the opinion of the judge. Such being the probative force of this testimony, if taken by itself, can there be any colour of reason for saying of it, that it will be destroyed by the addition of a quantity of the same force, a thousand times as great?
If such be the case while the witnesses are supposed to be all of them on the same side, still more manifestly will it be so, if, so many speaking in affirmation of the fact, so many others in negation of it, the number of them be supposed to be on each side the same. In this way, let there be two thousand of them, the probative force of the two thousand and first will be no less perceptible and efficient than if he had been the only one.
Moreover, by this same example it seems manifested, that it is not possible that the probative force of testimony, nor, therefore, that the force of persuasion on the part of the judge (to which may be added, on the part of any witness taken by himself) should, on the side of augmentation, have any certain limit. It can never be so great but that it would be capable of being rendered still greater.
In these circumstances, to allow to any person, either in the station of witness or in that of judge, the faculty of adding at pleasure to the declared force of his persuasion, would be to allow of an operation at the same time endless, useless, and ridiculous. Whatever latitude would in this respect be allowed to any one such person, would be to be allowed to every other. But the tendency of persuasion in one mind being to propagate like persuasion in other minds, and every such act of propagation being an exercise of power, the natural tendency of such an allowance would be a sort of auction, on the one part between witness and witness, on the other part between judge and judge; and in both cases, an auction that would have no end. It being of the number of those cases in which insincerity and abuse would be altogether incapable of detection, it would also be of the number of those cases in which insincerity is universal, or little short of it.
But suppose again (impossible as the supposition is,) that the highest possible degree of persuasion could, by means of such a scale, be reached and expressed, still in practice it would be useless; since no greater effect could be given to the maximum, the expression of which is the supposed result and fruit of the scale, than at present is given to the ordinary assertion, expressed in ordinary language, and without the use of any such scale. Of this simple assertion the effect is to act with the whole probative force of the testimony of the witness—with the whole force of the suffrage of the judge; and from the highest degree of persuasion,—were it possible, by the help of any such scale, to reach it and express it,—no greater effect could ensue.
From the allowance of a scale of the opposite description, limited on the side of increase (limited in effect by its being raised up, as under the present practice, to its maximum, in every case in which no scale is employed,) beneficial effects might be produced in some cases, no evil could be produced in any case.
Of the good effect, the nature has already been brought to view: the decision rendered conformable to justice, in cases in which, without the benefit of this instrument, it could not be conformable.
Abuse there could be none—insincerity there could be none: whether in the station of witness or in that of judge, a more irrefragable proof of sincerity could not be given, than by having recourse to such allowance.
By representing the force of his persuasion as lower than it is, what advantage could a man gain by the use of such a scale, more than he could gain without it?
Yes (it may be said,) a man may in this way diminish the declared force of his persuasion, and thence the probative force of his testimony, contrary to truth, and yet without risk. Placing it on the wrong side, the falsehood of the declaration might be proved from other sources, and he punished for it as in case of perjury: but placing it on the right side, though at the wrong end, viz. at the very bottom—at I, when it ought to have been at the very top, viz. at 10—he may thus, without risk, strike off nine-tenths of the force of his testimony: which defalcation, if there be many testimonies on both sides, may turn the scale.
Answer: True: in this case, he will save himself from punishment: but neither will he produce the mischief aimed at. Whatever force of counter-evidence would, in case of his placing his declared persuasion on the wrong side, have been sufficient to convict him to the purpose of punishment, the same counter-evidence will, now that he has placed it at the wrong end of the scale, though on the right side, be, notwithstanding his endeavours, sufficient to prevent the abatement thus made in the degree of persuasion declared, from producing the corresponding diminution of probative force. He will not have it in his power to cut off a part of the force of his testimony from the side of truth, except in circumstances which would have allowed him with safety to throw it entire into the scale of falsehood.
NOTE BY THE EDITOR.
M. Dumont, in a note to the Traité des Preuves Judiciaires, has brought forward several objections against the scale which Mr. Bentham has suggested for the measurement of degrees of persuasion and probative force. It is fair that the reader should have the means of judging for himself, what degree of validity these objections possess. I quote from a recently published and very well executed translation of M. Dumont’s work. [See “A Treatise on Judicial Evidence, extracted from the MSS. of Jeremy Bentham, by M. Dumont, translated into English, 1825.” 8vo. p. 45.
“I do not dispute the correctness of the author’s principles; and I cannot deny that, where different witnesses have different degrees of belief, it would be extremely desirable to obtain a precise knowledge of these degrees, and to make it the basis of the judicial decision. But I cannot believe that this sort of perfection is attainable in practice. I even think, that it belongs only to intelligences, superior to ourselves, or at least to the great mass of mankind. Looking into myself, and supposing that I am examined in a court of justice on various facts, if I cannot answer ‘Yes’ or ‘No’ with all the certainty which my mind can allow, if there be degrees and shades, I feel myself incapable of distinguishing between two and three, between four and five, and even between more distant degrees. I make the experiment at this very moment: I try to recollect who told me a certain fact: I hesitate—I collect all the circumstances—I think it was A rather than B: but should I place my belief at No. 4, or at No. 7? I cannot tell.
“A witness who says, ‘I am doubtful,’ says nothing at all, in so far as the judge is concerned. It serves no purpose, I think, to inquire after the degrees of doubt. But these different states of belief, which, in my opinion, it is difficult to express in numbers, display themselves to the eyes of the judge by other signs. The readiness of the witness, the distinctness and certainty of his answers, the agreement of all the circumstances of his story with each other,—it is this which shows the confidence of the witness in himself. Hesitation, a painful searching for the details, successive connexions of his own testimony,—it is this which announces a witness who is not at the maximum of certainty. It belongs to the judge to appreciate these differences, rather than to the witness himself, who would be greatly embarrassed if he had to fix the numerical amount of his own belief.
“Were this scale adopted, I should be apprehensive that the authority of the testimony would often be inversely as the wisdom of the witnesses. Reserved men—men who knew what doubt is—would, in many cases, place themselves at inferior degrees, rather than at the highest; while those of a positive and presumptuous disposition, above all, passionate men, would almost believe they were doing themselves an injury, if they did not take their station immediately at the highest point. The wisest thus leaning to a diminution, and the least wise to an augmentation, of their respective influence on the judge, the scale might produce an effect contrary to what the author expects from it.
“The comparison with wagers and insurances does not seem to me to be applicable. Testimony turns on past events: wagers turn on future events: as a witness, I know, I believe, or I doubt; as a wagerer, I know nothing, but I conjecture, I calculate probabilities—my rashness can injure nobody but myself: and if a wagerer feels that he has gone too far, he often diminishes the chances of loss by betting on the other side.
“It appears to me, that in judicial matters the true security depends on the degree in which the judges are acquainted with the nature of evidence, the appreciation of testimony, and the different degrees of proving power. These principles put a balance into their hands, in which witnesses can be weighed much more accurately than if they were allowed to assign their own value; and even if the scale of the degrees of belief were adopted, it would still be necessary to leave judges the power of appreciating the intelligence and morality of the witnesses, in order to estimate the confidence due to the numerical point of belief at which they have placed their testimony.
“These are the difficulties which have presented themselves to me, in meditating on this new method.”
On these observations of M. Dumont it may, in the first place, be remarked, that if applicable at all, they are applicable only to the use of the scale by the witness, not to the use of it by the judge; which latter use, however, is perhaps the more important of the two. In the next place, even as regards the witness, I doubt whether any great weight should be attached to the objections. For, first, what almost all of them seem to imply is, that because we cannot in all cases attain the degree of exactness which is desirable, therefore we ought to neglect the means of attaining that degree of exactness which is in our power. The witness who does not know the degree of his persuasion—the witness to whom the scale would be useless—will not call for it: the judge will at all events have the same means of appreciating his testimony, as he has now, and will not be the more likely to be deceived by a witness who does not use the scale, because it has happened to him to have received the testimony of one who does.
Secondly, the most formidable in appearance of all M. Dumont’s objections—I mean that which is contained in his third paragraph—seems to me, if it prove anything, to prove much more than M. Dumont intended. The wise (says he) will place their degree of persuasion lower than they ought, the foolish higher than they ought: the effect, therefore of the scale, is to give greater power to the foolish than they otherwise would have, and less power to the wise. But if this be true, what does it prove? That different degrees of persuasion should not be suffered to be indicated at all; that no one should be suffered to say he doubts. It is not the scale which does the mischief, if mischief there be. There are but two sorts of witnesses—the wise and the foolish: grant to them the privilege of expressing doubt, or any degree of persuasion short of the highest; and the foolish, says M. Dumont, will make no use of the privilege, the wise will make a bad use. But if so, would it not be better to withhold the privilege altogether? Is it the scale which makes all the difference?
The truth seems to me to be, that the scale will neither add to the power of the foolish witness, nor unduly diminish that of the wise one. It will not add to the power of the foolish witness; because he cannot place his persuasion higher than the highest point in the scale; and this is no more than he could do without it. It will not unduly diminish the power of the wise witness; because the wise witness will know tolerably well what degree of persuasion he has grounds for, and will therefore know tolerably well whereabouts to place himself in the scale. That he would be likely to place himself too low, seems to me a mere assumption. The wiser a man becomes, the more certainly will he doubt, where evidence is insufficient, and scepticism justifiable; but as his wisdom increases, so also will his confidence increase, in all those cases in which there is sufficient evidence to warrant a positive conclusion.
[* ]In the history of English judicature, an instance is upon record, in which a jury, finding a difficulty in settling the degree of their respective persuasions, sought for their consciences a relief, which, by men of hardened consciences, was imputed to them as a crime. The verdict, the result of the aggregate of their persuasions, was left to the decision of cross and pile. The verdict was set aside, and those who pronounced it (if I mistake not) were punished.
[† ]In the present instance, the seat and station of improvement, if the idea have any title to that name, is in language; but language, though itself the instrument of all other improvement, and standing to the full as much in need of improvement as any other instrument, is in a more particular degree averse to improvement: at least in those points of it which, not belonging, or not appearing to belong, to the demesne of any particular art or science, are conceived to belong in common to the great body of the people. Chemistry, for example, having for its subjects a multitude of things with which none are conversant but those who have devoted themselves to the science, amendments of every kind, to that part of the language, are daily suffered, and received without murmur or repugnance. Not so in the case of morals: this is considered as common land, and every improvement is resisted as an encroachment: always excepted those productions of lawyer-craft which have been forced into the language of the law, beyond all power of resistance, by the combined force of coercive power and imposture.
[* ]See Chap. III. Facts.
[* ]In a case considered as being of importance, in English practice, shades of difference in the form of persuasion on the part of this or that judge, have not unfrequently been endeavoured to be expressed in ordinary language: matter of vague dissertation, and sometimes of secret history.
[† ]See Book V. Circumstantial.
[* ]English Liturgy, Athanasian Creed, &c.
[† ]Harrison’s Chancery, I. 222. Rules and Orders of the Court of Chancery, p. 99, edit. 1739.—See infra, section 5.
[‡ ]Thus, in the English language, the command intimated by that future which is expressed by the word shall, is more imperative, indicative of a stronger exertion of will, than the command expressed by the word to which alone the denomination of imperative mood has been commonly affixed by grammarians: the command expressed by you shall pay me, is more strongly imperative than the command expressed by the words pay me. By the imperative, so called, nothing more is expressed than the bias given to the will of him who speaks. By the future above mentioned, not only the existence of the will is denoted, but the futurity of the event which is the object of it, is predicted as certain; an intimation being moreover given of the event as being about to have for its cause the will that has been thus expressed. Such is the power of my will, that the event of which it seeks to be productive cannot fail of taking place.
[∥ ]Elem. Jur. Civ. (ad Pandect.) pars iv. § 18.
[* ]See Book IX. Exclusion. Part VI. Disguised. Chap. I. Exclusion for want of multiplicity.
[† ]Ordonn. Crim. p. 375.
[‡ ]Coke Litt. 6.
[∥ ]Bl. Com. III. 371, chap. 23.
[§ ]Rules and Orders of Chancery, as published by the Lord Chancellor Clarendon, and the Master of the Rolls Sir Harbottle Grimstone, without date, but at a period immediately preceding the 27th February, 19 Car. II. 1667, p. 99, edition of 1739; and quoted as subsisting in Mr. Parker’s edition of Harrison’s Practice of the Court of Chancery, 8th edit. 1796.
[* ]Fowler’s Exchequer, I. 421, anno 1793.