A System of Logic: Ratiocinative and Inductive Volume II Part 19

As a first instance, we may cite that favourite argument in defence of absolute power, drawn from the a.n.a.logy of paternal government in a family, which government, however much in need of control, is not and cannot be controlled by the children themselves, while they remain children. Paternal government, says the argument, works well; therefore, despotic government in a state will work well. I wave, as not pertinent in this place, all that could be said in qualification of the alleged excellence of paternal government. However this might be, the argument from the family to the state would not the less proceed on a false a.n.a.logy; implying that the beneficial working of parental government depends, in the family, on the only point which it has in common with political despotism, namely, irresponsibility. Whereas it depends, when real, not on that but on two other circ.u.mstances of the case, the affection of the parent for the children, and the superiority of the parent in wisdom and experience; neither of which properties can be reckoned on, or are at all likely to exist, between a political despot and his subjects; and when either of these circ.u.mstances fails even in the family, and the influence of the irresponsibility is allowed to work uncorrected, the result is anything but good government. This, therefore, is a false a.n.a.logy.

Another example is the not uncommon _dictum_, that bodies politic have youth, maturity, old age, and death, like bodies natural: that after a certain duration of prosperity, they tend spontaneously to decay. This also is a false a.n.a.logy, because the decay of the vital powers in an animated body can be distinctly traced to the natural progress of those very changes of structure which, in their earlier stages, const.i.tute its growth to maturity: while in the body politic the progress of those changes cannot, generally speaking, have any effect but the still further continuance of growth: it is the stoppage of that progress, and the commencement of retrogression, that alone would const.i.tute decay.

Bodies politic die, but it is of disease, or violent death: they have no old age.

The following sentence from Hooker's _Ecclesiastical Polity_ is an instance of a false a.n.a.logy from physical bodies to what are called bodies politic. "As there could be in natural bodies no motion of anything unless there were some which moveth all things, and continueth immovable: even so in politic societies there must be some unpunishable, or else no man shall suffer punishment." There is a double fallacy here, for not only the a.n.a.logy, but the premise from which it is drawn, is untenable. The notion that there must be something immovable which moves all other things, is the old scholastic error of a _primum mobile_.

The following instance I quote from Archbishop Whately's _Rhetoric_: "It would be admitted that a great and permanent diminution in the quant.i.ty of some useful commodity, such as corn, or coal, or iron, throughout the world, would be a serious and lasting loss; and again, that if the fields and coal mines yielded regularly double quant.i.ties, with the same labour, we should be so much the richer; hence it might be inferred, that if the quant.i.ty of gold and silver in the world were diminished one-half, or were doubled, like results would follow; the utility of these metals, for the purposes of coin, being very great. Now there are many points of resemblance and many of difference, between the precious metals on the one hand, and corn, coal, &c., on the other; but the important circ.u.mstance to the supposed argument is, that the _utility_ of gold and silver (as coin, which is far the chief) _depends on their value_, which is regulated by their scarcity; or rather, to speak strictly, by the difficulty of obtaining them; whereas, if corn and coal were ten times as abundant (_i.e._ more easily obtained), a bushel of either would still be as useful as now. But if it were twice as easy to procure gold as it is, a sovereign would be twice as large; if only half as easy it would be of the size of a half-sovereign, and this (besides the trifling circ.u.mstance of the cheapness or dearness of gold ornaments) would be all the difference. The a.n.a.logy, therefore, fails in the point essential to the argument."

The same author notices, after Bishop Copleston, the case of False a.n.a.logy which consists in inferring from the similarity in many respects between the metropolis of a country and the heart of the animal body, that the increased size of the metropolis is a disease.

Some of the false a.n.a.logies on which systems of physics were confidently grounded in the time of the Greek philosophers, are such as we now call fanciful, not that the resemblances are not often real, but that it is long since any one has been inclined to draw from them the inferences which were then drawn. Such, for instance, are the curious speculations of the Pythagoreans on the subject of numbers. Finding that the distances of the planets bore or seemed to bear to one another a proportion not varying much from that of the divisions of the monochord, they inferred from it the existence of an inaudible music, that of the spheres: as if the music of a harp had depended solely on the numerical proportions, and not on the material, nor even on the existence of any material, any strings at all. It has been similarly imagined that certain combinations of numbers, which were found to prevail in some natural phenomena, must run through the whole of nature: as that there must be four elements, because there are four possible combinations of hot and cold, wet and dry; that there must be seven planets, because there were seven metals, and even because there were seven days of the week. Kepler himself thought that there could be only six planets because there were only five regular solids. With these we may cla.s.s the reasonings, so common in the speculations of the ancients, founded on a supposed _perfection_ in nature: meaning by nature the customary order of events as they take place of themselves without human interference.

This also is a rude guess at an a.n.a.logy supposed to pervade all phenomena, however dissimilar. Since what was thought to be perfection appeared to obtain in some phenomena, it was inferred (in opposition to the plainest evidence) to obtain in all. "We always suppose that which is better to take place in nature, if it be possible," says Aristotle: and the vaguest and most heterogeneous qualities being confounded together under the notion of being _better_, there was no limit to the wildness of the inferences. Thus, because the heavenly bodies were "perfect," they must move in circles and uniformly. For "they" (the Pythagoreans) "would not allow," says Geminus,[30] "of any such disorder among divine and eternal things, as that they should sometimes move quicker and sometimes slower, and sometimes stand still; for no one would tolerate such anomaly in the movements even of a man, who was decent and orderly. The occasions of life, however, are often reasons for men going quicker or slower; but in the incorruptible nature of the stars, it is not possible that any cause can be alleged of quickness or slowness." It is seeking an argument of a.n.a.logy very far, to suppose that the stars must observe the rules of decorum in gait and carriage, prescribed for themselves by the long-bearded philosophers satirized by Lucian.

As late as the Copernican controversy it was urged as an argument in favour of the true theory of the solar system, that it placed the fire, the n.o.blest element, in the centre of the universe. This was a remnant of the notion that the order of nature must be perfect, and that perfection consisted in conformity to rules of precedency in dignity, either real or conventional. Again, reverting to numbers: certain numbers were _perfect_, therefore those numbers must obtain in the great phenomena of nature. Six was a perfect number, that is, equal to the sum of all its factors; an additional reason why there must be exactly six planets. The Pythagoreans, on the other hand, attributed perfection to the number ten; but agreed in thinking that the perfect number must be somehow realized in the heavens; and knowing only of nine heavenly bodies, to make up the enumeration, they a.s.serted "that there was an _antichthon_ or counter-earth, on the other side of the sun, invisible to us."[31] Even Huygens was persuaded that when the number of the heavenly bodies had reached twelve, it could not admit of any further increase. Creative power could not go beyond that sacred number.

Some curious instances of false a.n.a.logy are to be found in the arguments of the Stoics to prove the equality of all crimes, and the equal wretchedness of all who had not realized their idea of perfect virtue.

Cicero, towards the end of his Fourth Book _De Finibus_, states some of these as follows. "Ut, inquit, in fidibus plurimis, si nulla earum ita contenta numeris sit, ut concentum servare possit, omnes que incontent sunt; sic peccata, quia discrepant, que discrepant; paria sunt igitur."

To which Cicero himself aptly answers, "que contingit omnibus fidibus, ut incontent sint; illud non continuo, ut que incontent." The Stoic resumes: "Ut enim, inquit, gubernator que peccat, si palcarum navem evert.i.t, et si auri; item que peccat qui parentem, et qui servum, injuri verberat;" a.s.suming, that because the magnitude of the interest at stake makes no difference in the mere defect of skill, it can make none in the moral defect: a false a.n.a.logy. Again, "Quis ignorat, si plures ex alto emergere velint, propius fore eos quidem ad respirandum, qui ad summam jam aquam appropinquant, sed nihilo magis respirare posse, quam eos, qui sunt in profundo? Nihil ergo adjuvat procedere, et progredi in virtute, quominus miserrimus sit, antequam ad eam pervenerit, quoniam in aqu nihil adjuvat: et quoniam catuli, qui jam despecturi sunt, cci que, et ii qui modo nati; Platonem quoque necesse est, quoniam nondum videbat sapientiam, que cc.u.m animo, ac Phalarim fuisse." Cicero, in his own person, combats these false a.n.a.logies by other a.n.a.logies tending to an opposite conclusion. "Ista similia non sunt, Cato.... Illa sunt similia; hebes acies est cuipiam oculorum: corpore alius languescit: hi curatione adhibit levantur in dies: alter valet plus quotidie: alter videt. Hi similes sunt omnibus, qui virtuti student; levantur vitiis, levantur erroribus."

7. In these and all other arguments drawn from remote a.n.a.logies, and from metaphors, which are cases of a.n.a.logy, it is apparent (especially when we consider the extreme facility of raising up contrary a.n.a.logies and conflicting metaphors) that so far from the metaphor or a.n.a.logy proving anything, the applicability of the metaphor is the very thing to be made out. It has to be shown that in the two cases a.s.serted to be a.n.a.logous, the same law is really operating; that between the known resemblance and the inferred one there is some connexion by means of causation. Cicero and Cato might have bandied opposite a.n.a.logies for ever; it rested with each of them to prove by just induction, or at least to render probable, that the case resembled the one set of a.n.a.logous cases and not the other, in the circ.u.mstances on which the disputed question really hinged. Metaphors, for the most part, therefore, a.s.sume the proposition which they are brought to prove: their use is, to aid the apprehension of it; to make clearly and vividly comprehended what it is that the person who employs the metaphor is proposing to make out; and sometimes also, by what media he proposes to do so. For an apt metaphor, though it cannot prove, often suggests the proof.

For instance, when D'Alembert (I believe) remarked that in certain governments, only two creatures find their way to the highest places, the eagle and the serpent; the metaphor not only conveys with great vividness the a.s.sertion intended, but contributes towards substantiating it, by suggesting, in a lively manner, the means by which the two opposite characters thus typified effect their rise. When it is said that a certain person misunderstands another because the lesser of two objects cannot comprehend the greater, the application of what is true in the literal sense of the word _comprehend_, to its metaphorical sense, points to the fact which is the ground and justification of the a.s.sertion, viz. that one mind cannot thoroughly understand another unless it can contain it in itself, that is, unless it possesses all that is contained in the other. When it is urged as an argument for education, that if the soil is left uncultivated, weeds will spring up, the metaphor, though no proof, but a statement of the thing to be proved, states it in terms which, by suggesting a parallel case, put the mind upon the track of the real proof. For, the reason why weeds grow in an uncultivated soil, is that the seeds of worthless products exist everywhere, and can germinate and grow in almost all circ.u.mstances, while the reverse is the case with those which are valuable; and this being equally true of mental products, this mode of conveying an argument, independently of its rhetorical advantages, has a logical value; since it not only suggests the grounds of the conclusion, but points to another case in which those grounds have been found, or at least deemed to be, sufficient.

On the other hand, when Bacon, who is equally conspicuous in the use and abuse of figurative ill.u.s.tration, says that the stream of time has brought down to us only the least valuable part of the writings of the ancients, as a river carries froth and straws floating on its surface, while more weighty objects sink to the bottom; this, even if the a.s.sertion ill.u.s.trated by it were true, would be no good ill.u.s.tration, there being no parity of cause. The levity by which substances float on a stream, and the levity which is synonymous with worthlessness, have nothing in common except the name; and (to show how little value there is in the metaphor) we need only change the word into _buoyancy_, to turn the semblance of argument involved in Bacon's ill.u.s.tration against himself.

A metaphor, then, is not to be considered as an argument, but as an a.s.sertion that an argument exists; that a parity subsists between the case from which the metaphor is drawn and that to which it is applied.

This parity may exist though the two cases be apparently very remote from one another; the only resemblance existing between them may be a resemblance of relations, an a.n.a.logy in Ferguson's and Archbishop Whately's sense: as in the preceding instance, in which an ill.u.s.tration from agriculture was applied to mental cultivation.

8. To terminate the subject of Fallacies of Generalization, it remains to be said, that the most fertile source of them is bad cla.s.sification: bringing together in one group, and under one name, things which have no common properties, or none but such as are too unimportant to allow general propositions of any considerable value to be made respecting the cla.s.s. The misleading effect is greatest, when a word which in common use expresses some definite fact, is extended by slight links of connexion to cases in which that fact does not exist, but some other or others, only slightly resembling it. Thus Bacon,[32] in speaking of the _Idola_ or Fallacies arising from notions _temere et inqualiter rebus abstract_, exemplifies them by the notion of Humidum or Wet, so familiar in the physics of antiquity and of the middle ages. "Invenietur verb.u.m istud, Humidum, nihil aliud quam nota confusa diversarum actionum, qu nullam constantiam aut reductionem patiuntur. Significat enim, et quod circa aliud corpus facile se circ.u.mfundit; et quod in se est indeterminabile, nec consistere potest; et quod facile cedit undique; et quod facile se dividit et dispergit; et quod facile se unit et colligit; et quod facile fluit, et in motu ponitur; et quod alteri corpori facile adhret, idque madefacit; et quod facile reducitur in liquidum, sive colliquatur, c.u.m antea consisteret. Itaque quum ad hujus nominis prdicationem et impositionem ventum sit; si alia accipias, flamma humida est; si alia accipias, aer humidus non est; si alia, pulvis minutus humidus est; si alia, vitrum humidum est: ut facile appareat, istam notionem ex aqu tantum, et communibus et vulgaribus liquoribus, absque ull debit verificatione, temere abstractam esse."

Bacon himself is not exempt from a similar accusation when inquiring into the nature of heat: where he occasionally proceeds like one who seeking for the cause of hardness, after examining that quality in iron, flint, and diamond, should expect to find that it is something which can be traced also in hard water, a hard knot, and a hard heart.

The word _????s??_ in the Greek philosophy, and the words Generation and Corruption both then and long afterwards, denoted such a mult.i.tude of heterogeneous phenomena, that any attempt at philosophizing in which those words were used was almost as necessarily abortive as if the word _hard_ had been taken to denote a cla.s.s including all the things mentioned above. _????s??_, for instance, which properly signified motion, was taken to denote not only all motion but even all change: _??????s??_ being recognised as one of the modes of _????s??_. The effect was, to connect with every form of _??????s??_ or change, ideas drawn from motion in the proper and literal sense, and which had no real connexion with any other kind of _????s??_ than that. Aristotle and Plato laboured under a continual embarra.s.sment from this misuse of terms. But if we proceed further in this direction we shall encroach upon the Fallacy of Ambiguity, which belongs to a different cla.s.s, the last in order of our cla.s.sification, Fallacies of Confusion.

CHAPTER VI.

FALLACIES OF RATIOCINATION.

1. We have now, in our progress through the cla.s.ses of Fallacies, arrived at those to which, in the common books of logic, the appellation is in general exclusively appropriated; those which have their seat in the ratiocinative or deductive part of the investigation of truth. On these fallacies it is the less necessary for us to insist at any length, as they have been most satisfactorily treated in a work familiar to almost all, in this country at least, who feel any interest in these speculations, Archbishop Whately's _Logic_. Against the more obvious forms of this cla.s.s of fallacies, the rules of the syllogism are a complete protection. Not (as we have so often said) that the ratiocination cannot be good unless it be in the form of a syllogism; but that, by showing it in that form, we are sure to discover if it be bad, or at least if it contain any fallacy of this cla.s.s.

2. Among Fallacies of Ratiocination, we ought perhaps to include the errors committed in processes which have the appearance only, not the reality, of an inference from premises; the fallacies connected with the conversion and quipollency of propositions. I believe errors of this description to be far more frequently committed than is generally supposed, or than their extreme obviousness might seem to admit of. For example, the simple conversion of an universal affirmative proposition, All A are B, therefore all B are A, I take to be a very common form of error: though committed, like many other fallacies, oftener in the silence of thought than in express words, for it can scarcely be clearly enunciated without being detected. And so with another form of fallacy, not substantially different from the preceding: the erroneous conversion of an hypothetical proposition. The proper converse of an hypothetical proposition is this: If the consequent be false, the antecedent is false; but this, If the consequent be true, the antecedent is true, by no means holds good, but is an error corresponding to the simple conversion of an universal affirmative. Yet hardly anything is more common than for people, in their private thoughts, to draw this inference. As when the conclusion is accepted, which it so often is, for proof of the premises. That the premises cannot be true if the conclusion is false, is the unexceptionable foundation of the legitimate mode of reasoning called a _reductio ad absurdum_. But people continually think and express themselves, as if they also believed that the premises cannot be false if the conclusion is true. The truth, or supposed truth, of the inferences which follow from a doctrine, often enables it to find acceptance in spite of gross absurdities in it. How many philosophical systems which had scarcely any intrinsic recommendation, have been received by thoughtful men because they were supposed to lend additional support to religion, morality, some favourite view of politics, or some other cherished persuasion: not merely because their wishes were thereby enlisted on its side, but because its leading to what they deemed sound conclusions appeared to them a strong presumption in favour of its truth: though the presumption, when viewed in its true light, amounted only to the absence of that particular evidence of falsehood, which would have resulted from its leading by correct inference to something already known to be false.

Again, the very frequent error in conduct, of mistaking reverse of wrong for right, is the practical form of a logical error with respect to the Opposition of Propositions. It is committed for want of the habit of distinguis.h.i.+ng the _contrary_ of a proposition from the _contradictory_ of it, and of attending to the logical canon, that contrary propositions, though they cannot both be true, may both be false. If the error were to express itself in words, it would run distinctly counter to this canon. It generally, however, does not so express itself, and to compel it to do so is the most effectual method of detecting and exposing it.

3. Among Fallacies of Ratiocination are to be ranked in the first place, all the cases of vicious syllogism laid down in the books. These generally resolve themselves into having more than three terms to the syllogism, either avowedly, or in the covert mode of an undistributed middleterm, or an _illicit process_ of one of the two extremes. It is not, indeed, very easy fully to convict an argument of falling under any one of these vicious cases in particular; for the reason already more than once referred to, that the premises are seldom formally set out: if they were, the fallacy would impose upon n.o.body; and while they are not, it is almost always to a certain degree optional in what manner the suppressed link shall be filled up. The rules of the syllogism are rules for compelling a person to be aware of the whole of what he must undertake to defend if he persists in maintaining his conclusion. He has it almost always in his power to make his syllogism good by introducing a false premise; and hence it is scarcely ever possible decidedly to affirm that any argument involves a bad syllogism: but this detracts nothing from the value of the syllogistic rules, since it is by them that a reasoner is compelled distinctly to make his election what premises he is prepared to maintain. The election made, there is generally so little difficulty in seeing whether the conclusion follows from the premises set out, that we might without much logical impropriety have merged this fourth cla.s.s of fallacies in the fifth, or Fallacies of Confusion.

4. Perhaps, however, the commonest, and certainly the most dangerous fallacies of this cla.s.s, are those which do not lie in a single syllogism, but slip in between one syllogism and another in a chain of argument, and are committed by _changing the premises_. A proposition is proved, or an acknowledged truth laid down, in the first part of an argumentation, and in the second a further argument is founded not on the same proposition, but on some other, resembling it sufficiently to be mistaken for it. Instances of this fallacy will be found in almost all the argumentative discourses of unprecise thinkers; and we need only here advert to one of the obscurer forms of it, recognised by the schoolmen as the fallacy _ dicto secundum quid ad dictum simpliciter_.

This is committed when, in the premises, a proposition is a.s.serted with a qualification, and the qualification lost sight of in the conclusion; or oftener, when a limitation or condition, though not a.s.serted, is necessary to the truth of the proposition, but is forgotten when that proposition comes to be employed as a premise. Many of the bad arguments in vogue belong to this cla.s.s of error. The premise is some admitted truth, some common maxim, the reasons or evidence for which have been forgotten, or are not thought of at the time, but if they had been thought of would have shown the necessity of so limiting the premise that it would no longer have supported the conclusion drawn from it.

Of this nature is the fallacy in what is called, by Adam Smith and others, the Mercantile Theory in Political Economy. That theory sets out from the common maxim, that whatever brings in money enriches; or that every one is rich in proportion to the quant.i.ty of money he obtains.

From this it is concluded that the value of any branch of trade, or of the trade of the country altogether, consists in the balance of money it brings in; that any trade which carries more money out of the country than it draws into it is a losing trade; that therefore money should be attracted into the country and kept there, by prohibitions and bounties: and a train of similar corollaries. All for want of reflecting that if the riches of an individual are in proportion to the quant.i.ty of money he can command, it is because that is the measure of his power of purchasing money's worth; and is therefore subject to the proviso that he is not debarred from employing his money in such purchases. The premise, therefore, is only true _secundum quid_; but the theory a.s.sumes it to be true absolutely, and infers that increase of money is increase of riches, even when produced by means subversive of the condition under which alone money can be riches.

A second instance is, the argument by which it used to be contended, before the commutation of t.i.the, that t.i.thes fell on the landlord, and were a deduction from rent; because the rent of t.i.the-free land was always higher than that of land of the same quality, and the same advantages of situation, subject to t.i.the. Whether it be true or not that a t.i.the falls on rent, a treatise on Logic is not the place to examine; but it is certain that this is no proof of it. Whether the proposition be true or false, t.i.the-free land must, by the necessity of the case, pay a higher rent. For if t.i.thes do not fall on rent, it must be because they fall on the consumer; because they raise the price of agricultural produce. But if the produce be raised in price, the farmer of t.i.the-free as well as the farmer of t.i.thed land gets the benefit. To the latter the rise is but a compensation for the t.i.the he pays; to the first, who pays none, it is clear gain, and therefore enables him, and if there be freedom of compet.i.tion forces him, to pay so much more rent to his landlord. The question remains, to what cla.s.s of fallacies this belongs. The premise is, that the owner of t.i.thed land receives less rent than the owner of t.i.the-free land; the conclusion is, that therefore he receives less than he himself would receive if t.i.the were abolished. But the premise is only true conditionally; the owner of t.i.thed land receives less than what the owner of t.i.the-free land is enabled to receive _when other lands are t.i.thed_; while the conclusion is applied to a state of circ.u.mstances in which that condition fails, and in which, by consequence, the premise would not be true. The fallacy, therefore, is _ dicto secundum quid ad dictum simpliciter_.

A third example is the opposition sometimes made to legitimate interferences of government in the economical affairs of society, grounded on a misapplication of the maxim, that an individual is a better judge than the government, of what is for his own pecuniary interest. This objection was urged to Mr. Wakefield's principle of colonization; the concentration of the settlers, by fixing such a price on unoccupied land as may preserve the most desirable proportion between the quant.i.ty of land in culture, and the labouring population. Against this it was argued, that if individuals found it for their advantage to occupy extensive tracts of land, they, being better judges of their own interest than the legislature (which can only proceed on general rules) ought not to be restrained from doing so. But in this argument it was forgotten that the fact of a person's taking a large tract of land is evidence only that it is his interest to take as much as other people, but not that it might not be for his interest to content himself with less, if he could be a.s.sured that other people would do so too; an a.s.surance which nothing but a government regulation can give. If all other people took much, and he only a little, he would reap none of the advantages derived from the concentration of the population and the consequent possibility of procuring labour for hire, but would have placed himself, without equivalent, in a situation of voluntary inferiority. The proposition, therefore, that the quant.i.ty of land which people will take when left to themselves is that which is most for their interest to take, is true only _secundum quid_: it is only their interest while they have no guarantee for the conduct of one another.

But the arrangement disregards the limitation, and takes the proposition for true _simpliciter_.

One of the conditions oftenest dropped, when what would otherwise be a true proposition is employed as a premise for proving others, is the condition of _time_. It is a principle of political economy that prices, profits, wages, &c. "always find their level;" but this is often interpreted as if it meant that they are always, or generally, _at_ their level; while the truth is, as Coleridge epigrammatically expresses it, that they are always _finding_ their level, "which might be taken as a paraphrase or ironical definition of a storm."

Under the same head of fallacy (_ dicto secundum quid ad dictum simpliciter_) might be placed all the errors which are vulgarly called misapplications of abstract truths: that is, where a principle, true (as the common expression is) _in the abstract_, that is, all modifying causes being supposed absent, is reasoned on as if it were true absolutely, and no modifying circ.u.mstance could ever by possibility exist. This very common form of error it is not requisite that we should exemplify here, as it will be particularly treated of hereafter in its application to the subjects on which it is most frequent and most fatal, those of politics and society.[33]

CHAPTER VII.

FALLACIES OF CONFUSION.

1. Under this fifth and last cla.s.s it is convenient to arrange all those fallacies, in which the source of error is not so much a false estimate of the probative force of known evidence, as an indistinct, indefinite, and fluctuating conception of what the evidence is.

At the head of these stands that mult.i.tudinous body of fallacious reasonings, in which the source of error is the ambiguity of terms: when something which is true if a word be used in a particular sense, is reasoned on as if it were true in another sense. In such a case there is not a mal-estimation of evidence, because there is not properly any evidence to the point at all; there is evidence, but to a different point, which from a confused apprehension of the meaning of the terms used, is supposed to be the same. This error will naturally be oftener committed in our ratiocinations than in our direct inductions, because in the former we are deciphering our own or other people's notes, while in the latter we have the things themselves present, either to the senses or to the memory. Except, indeed, when the induction is not from individual cases to a generality, but from generalities to a still higher generalization; in that case the fallacy of ambiguity may affect the inductive process as well as the ratiocinative. It occurs in ratiocination in two ways: when the middleterm is ambiguous, or when one of the terms of the syllogism is taken in one sense in the premises, and in another sense in the conclusion.

Some good exemplifications of this fallacy are given by Archbishop Whately. "One case," says he, "which may be regarded as coming under the head of Ambiguous Middle, is (what I believe logical writers mean by '_Fallacia Figur Dictionis_,') the fallacy built on the grammatical structure of language, from men's usually taking for granted that _paronymous_ (or _conjugate_) words, _i.e._ those belonging to each other, as the substantive, adjective, verb, &c. of the same root, have a precisely corresponding meaning; which is by no means universally the case. Such a fallacy could not indeed be even exhibited in strict logical form, which would preclude even the attempt at it, since it has two middleterms in sound as well as sense. But nothing is more common in practice than to vary continually the terms employed, with a view to grammatical convenience; nor is there anything unfair in such a practice, as long as the _meaning_ is preserved unaltered; _e.g._ 'murder should be punished with death; this man is a murderer, therefore he deserves to die,' &c. Here we proceed on the a.s.sumption (in this case just) that to commit murder, and to be a murderer,--to deserve death, and to be one who ought to die, are, respectively, equivalent expressions; and it would frequently prove a heavy inconvenience to be debarred this kind of liberty; but the abuse of it gives rise to the Fallacy in question: _e.g._ _projectors_ are unfit to be trusted; this man has formed a _project_, therefore he is unfit to be trusted: here the sophist proceeds on the hypothesis that he who forms a _project_ must be a _projector_: whereas the bad sense that commonly attaches to the latter word, is not at all implied in the former. This fallacy may often be considered as lying not in the Middle, but in one of the terms of the Conclusion; so that the conclusion drawn shall not be, in reality, at all warranted by the premises, though it will appear to be so, by means of the grammatical affinity of the words: _e.g._ to be acquainted with the guilty is a _presumption_ of guilt; this man is so acquainted, therefore we may _presume_ that he is guilty: this argument proceeds on the supposition of an exact correspondence between _presume_ and _presumption_, which, however, does not really exist; for 'presumption' is commonly used to express a kind of _slight suspicion_; whereas, 'to presume' amounts to actual belief. There are innumerable instances of a non-correspondence in paronymous words, similar to that above instanced; as between _art_ and _artful_, _design_ and _designing_, _faith_ and _faithful_, &c.; and the more slight the variation of the meaning, the more likely is the fallacy to be successful; for when the words have become so widely removed in sense as 'pity' and 'pitiful,' every one would perceive such a fallacy, nor could it be employed but in jest.[34]

"The present Fallacy is nearly allied to, or rather, perhaps, may be regarded as a branch of, that founded on _etymology_; viz. when a term is used, at one time in its customary, and at another in its etymological sense. Perhaps no example of this can be found that is more extensively and mischievously employed than in the case of the word _representative_: a.s.suming that its right meaning must correspond exactly with the strict and original sense of the verb 'represent,' the sophist persuades the mult.i.tude, that a member of the House of Commons is bound to be guided in all points by the opinion of his const.i.tuents; and, in short, to be merely their _spokesman_; whereas law and custom, which in this case may be considered as fixing the meaning of the term, require no such thing, but enjoin the representative to act according to the best of his _own_ judgment, and on his own responsibility."

The following are instances of great practical importance, in which arguments are habitually founded on a verbal ambiguity.

The mercantile public are frequently led into this fallacy by the phrase, "scarcity of money." In the language of commerce "money" has two meanings: _currency_, or the circulating medium; and _capital seeking investment_, especially investment on loan. In this last sense the word is used when the "money market" is spoken of, and when the "value of money" is said to be high or low, the rate of interest being meant. The consequence of this ambiguity is, that as soon as scarcity of money in the latter of these senses begins to be felt,--as soon as there is difficulty of obtaining loans, and the rate of interest is high,--it is concluded that this must arise from causes acting upon the quant.i.ty of money in the other and more popular sense; that the circulating medium must have diminished in quant.i.ty, or ought to be increased. I am aware that, independently of the double meaning of the term, there are in facts themselves some peculiarities, giving an apparent support to this error; but the ambiguity of the language stands on the very threshold of the subject, and intercepts all attempts to throw light upon it.

Another ambiguous expression which continually meets us in the political controversies of the present time, especially in those which relate to organic changes, is the phrase "influence of property:" which is sometimes used for the influence of respect for superior intelligence, or grat.i.tude for the kind offices which persons of large property have it so much in their power to bestow; at other times for the influence of fear; fear of the worst sort of power, which large property also gives to its possessor, the power of doing mischief to dependents. To confound these two, is the standing fallacy of ambiguity brought against those who seek to purify the electoral system from corruption and intimidation. Persuasive influence, acting through the conscience of the voter, and carrying his heart and mind with it, is beneficial--therefore (it is pretended) coercive influence, which compels him to forget that he is a moral agent, or to act in opposition to his moral convictions, ought not to be placed under restraint.

Another word which is often turned into an instrument of the fallacy of ambiguity, is Theory. In its most proper acceptation, theory means the completed result of philosophical induction from experience. In that sense, there are erroneous as well as true theories, for induction may be incorrectly performed, but theory of some sort is the necessary result of knowing anything of a subject, and having put one's knowledge into the form of general propositions for the guidance of practice. In this, the proper sense of the word, Theory is the explanation of practice. In another and a more vulgar sense, theory means any mere fiction of the imagination, endeavouring to conceive how a thing may possibly have been produced, instead of examining how it was produced.

In this sense only are theory, and theorists, unsafe guides; but because of this, ridicule or discredit is attempted to be attached to theory in its proper sense, that is, to legitimate generalization, the end and aim of all philosophy; and a conclusion is represented as worthless, just because that has been done, which if done correctly, const.i.tutes the highest worth that a principle for the guidance of practice can possess, namely, to comprehend in a few words the real law on which a phenomenon depends, or some property or relation which is universally true of it.

"The Church" is sometimes understood to mean the clergy alone, sometimes the whole body of believers, or at least of communicants. The declamations respecting the inviolability of church property are indebted for the greater part of their apparent force to this ambiguity.

The clergy, being called the church, are supposed to be the real owners of what is called church property; whereas they are in truth only the managing members of a much larger body of proprietors, and enjoy on their own part a mere usufruct, not extending beyond a life interest.

The following is a Stoical argument taken from Cicero _De Finibus_, book the third: "Quod est bonum, omne laudabile est. Quod autem laudabile est, omne honestum est. Bonum igitur quod est, honestum est." Here the ambiguous word is _laudabile_, which in the minor premise means anything which mankind are accustomed, on good grounds, to admire or value; as beauty, for instance, or good fortune: but in the major, it denotes exclusively moral qualities. In much the same manner the Stoics endeavoured logically to justify as philosophical truths, their figurative and rhetorical expressions of ethical sentiment: as that the virtuous man is alone free, alone beautiful, alone a king, &c. Whoever has virtue has Good (because it has been previously determined not to call anything else good); but, again, Good necessarily includes freedom, beauty, and even kings.h.i.+p, all these being good things; therefore whoever has virtue has all these.