The passage below is chapter vi of George Campbell's book The Philosophy of Rhetoric, published in 1776, where he argues against the utility of the 'school logic', i.e. traditional or Aristotelian logic.
It illustrates well the low point to which logic had fallen in the eighteenth century. (For more eighteenth-century musings about logic, see Reid's commentary on Aristotle's Organon). He repeats a point made by Locke, that 'the syllogistic art, with its figures and moods, serves more to display the ingenuity of the inventor, and to exercise the address and fluency of the learner, than to assist the diligent inquirer in his researches after truth'.
Campbell argues that syllogistic demonstration involves a petitio principii, i.e. it assumes as a premiss, the very thing it was to prove. For example:
All animals feel;
All horses are animals;
Therefore all horses feel.
A sceptic will object that the premisses are merely an affirmation of the point which he denies, i.e. all animals feel, is only a 'compendious expression', for all horses feel, all dogs feel, all camels feel, all eagles feel, and so on.
The objection is similar to the one expressed later by Mill (in the Logic museum here), except that Mill's example is where the minor premiss is a singular judgment (Socrates is a man), not a universal one (all horses are animals).
The passage is taken from the online edition here.
George Campbell, The Philosophy of Rhetoric
BOOK I. CHAP. VI. Of the Nature and Use of the scholastic art of Syllogizing.
HAVING in the preceding chapter endeavoured to trace the outlines of natural logic, perhaps with more minuteness than in such an inquiry as this was strictly necessary, it might appear strange to pass over in silence the dialectic of the schools; an art which, though now fallen into disrepute, maintained, for a tract of ages, the highest reputation among the learned. What was so long regarded as teaching the only legitimate use and application of our rational powers in the acquisition of knowledge, ought not surely, when we are employed in investigating the nature and the different sorts of evidence, to be altogether overlooked.
It is long since I was first convinced, by what Mr. Locke had said on the subject, that the syllogistic art, with its figures and moods, serves more to display the ingenuity of the inventor, and to exercise the address and fluency of the learner, than to assist the diligent inquirer in his researches after truth. The method of proving by syllogism, appears, even on a superficial review, both unnatural and prolix. The rules laid down for distinguishing the conclusive from the inconclusive forms of argument, the true syllogism from the various kinds of sophism, are at once cumbersome to the memory, and unnecessary in practice. No person, one may venture to pronounce, will ever be made a reasoner, who stands in need of them. In a word, the whole bears the manifest indications of an artificial and ostentatious parade of learning, calculated for giving the appearance of great profundity to what in fact is very shallow. Such, I acknowledge, have been, for a long time, my sentiments on the subject. On a nearer inspection, I cannot say I have found reason to alter them, though I think I have seen a little further into the nature of this disputative science, and consequently into the grounds of its futility. I shall, therefore, as briefly as possible, lay before the reader a few observations on the subject, and so dismiss this article.
Permit me only to premise in general, that I proceed all along on the supposition, that the reader hath some previous acquaintance with school logic. It would be extremely superfluous, in a work like this, to give even the shortest abridgment that could be made of an art so well known, and which is still to be found in many thousand volumes. On the other hand, it is not necessary that he be an adept in it; a mere smattering will sufficiently serve the present purpose.
My first observation is, that this method of arguing has not the least affinity to moral reasoning, the procedure in the one being the very reverse of that employed in the other. In moral reasoning we proceed by analysis, and ascend from particulars to universals; in syllogizing we proceed by synthesis, and descend from universals to particulars. The analytic is the only method which we can follow, in the acquisition of natural knowledge, or whatever regards actual existences; the synthetic is more properly the method that ought to be pursued, in the application of knowledge already acquired. It is for this reason it has been called the didactic method, as being the shortest way of communicating the principles of a science. But even in teaching, as often as we attempt, not barely to inform, but to convince, there is a necessity of recurring to the track in which the knowledge we would convey was first attained. Now, the method of reasoning by syllogism more resembles mathematical demonstration, wherein, from universal principles, called axioms, we deduce many truths, which, though general in their nature, may, when compared with those first principles, be justly styled particular. Whereas in all kinds of knowledge,wherein experience is our only guide, we can proceed to general truths solely by an induction of particulars.
Agreeably to this remark, if a syllogism be regular in mood and figure, and if the premises be true, the conclusion is infallible. The whole foundation of the syllogistic art lies in these two axioms: "Things which coincide with the same thing, coincide with one another;" and "Two things, whereof one does, and one does not coincide with the same thing, do not coincide with one another." On the former rest all the affirmative syllogisms, on the latter all the negative. Accordingly, there is no more mention here of probability and of degrees of evidence, than in the operations of geometry and algebra. It is true, indeed, that the term probable may be admitted into a syllogism, and make an essential part of the conclusion, and so it may also in an arithmetical computation; but this does not in the least affect what was advanced just now; for in all such cases, the probability itself is assumed in one of the premises: whereas, in the inductive method of reasoning, it often happens, that from certain facts we can deduce only probable consequences.
I observe secondly, that though this manner of arguing has more of the nature of scientific reasoning than of moral, it has, nevertheless, not been thought worthy of being adopted by mathematicians, as a proper method of demonstrating their theorems. I am satisfied that mathematical demonstration is capable of being moulded into the syllogistic form, having made the trial with success on some propositions. But that this form is a very incommodious one, and has many disadvantages, but not one advantage of that commonly practised, will be manifest to every one who makes the experiment. It is at once more indirect, more tedious, and more obscure. I may add, that if into those abstract sciences one were to introduce some specious fallacies, such fallacies could be much more easily sheltered under the awkward verbosity of this artificial method, than under the elegant simplicity of that which has hitherto been used.
My third remark, which, by the way, is directly consequent on the two former, shall be, that in the ordinary application of this art to matters with which we can be made acquainted only by experience, it can be of little or no utility. So far from leading the mind, agreeably to the design of all argument and investigation, from things known to things unknown, and by things evident to things obscure; its usual progress is, on the contrary, from things less known to things better known, and by things obscure to things evident. But that it may not be thought that I do injustice to the art by this representation, I must entreat that the few following considerations may be attended to.
When, in the way of induction, the mind proceeds from individual instances to the discovery of such truths as regard a species, and from these again to such as comprehend a genus, we may say with reason, that as we advance, there may be in every succeeding step, and commonly is, less certainty than in the preceding; but in no instance whatever can there be more. Besides, as the judgment formed concerning the less general was anterior to that formed concerning the more general, so the conviction is more vivid arising from both circumstances, that, being less general, it is more distinctly conceived, and being earlier, it is more deeply imprinted. Now, the customary procedure in the syllogistic science is, as was remarked, the natural method reversed, being from general to special, and consequently from less to more obvious. In scientific reasoning the case is very different, as the axioms, or universal truths from which the mathematician argues, are so far from being the slow result of induction and experience, that they are self-evident. They are no sooner apprehended than necessarily assented to.
But to illustrate the matter by examples, take the following specimen in Barbara, the first mood of the first figure:-
All animals feel;
All horses are animals;
Therefore all horses feel.
It is impossible that any reasonable man, who really doubts whether a horse has feeling or is a mere automaton, should be convinced by this argument. For, supposing he uses the names horse and animal, as standing in the same relation of species and genus which they bear in the common acceptation of the words, the argument you employ is, in effect, but an affirmation of the point which he denies, couched in such terms as include a multitude of other similar affirmations, which, whether true or false, are nothing to the purpose. Thus all animals feel, is only a compendious expression, for all horses feel, all dogs feel, all camels feel, all eagles feel, and so through the whole animal creation. I affirm, besides, that the procedure here is from things less known to things better known. It is possible that one may believe the conclusion who denies the major: but the reverse is not possible; for, to express myself in the language of the art, that may be predicated of the species, which is not predicable of the genus; but that can never be predicated of the genus, which is not predicable of the species. If one, therefore, were under such an error in regard to the brutes, true logic, which is always coincident with good sense, would lead our reflections to the indications of perception and feeling, given by these animals, andthe remarkable conformity which in this respect, and in respect to their bodily organs, they bear to our own species. It may be said, that if the subject of the question were a creature much more ignoble than the horse, there would be no scope for this objection to the argument. Substitute, then, the word oysters for horses in the minor, and it will stand thus,
All animals feel;
All oysters are animals;
Therefore all oysters feel.
In order to give the greater advantage to the advocate for this scholastic art, let us suppose the antagonist does not maintain the opposite side from any favour to Descartes' theory concerning brutes, but from some notion entertained of that particular order of beings which is the subject of dispute. It is evident, that though he should admit the truth of the major, he would regard the minor as merely another manner of expressing the conclusion; for he would conceive an animal no otherwise than as a body endowed with sensation or feeling.
Sometimes, indeed, there is not in the premises any position more generic, under which the conclusion can be comprised. In this case you always find that the same proposition is exhibited in different words; insomuch that the stress of the argument lies in a mere synonyma or something equivalent. The following is an example:-
The Almighty ought to be worshipped;
God is the Almighty;
Therefore God ought to be worshipped.
It would be superfluous to illustrate that this argument could have no greater influence on the Epicurean, than the first mentioned one would have on the Cartesian. To suppose the contrary is to suppose the conviction effected by the charm of a sound, and not by the sense of what is advanced. Thus also the middle term and the subject frequently correspond to each other, as the definition, description, or circumlocution, and the name. Of this I shall give an example in Disamis, as in the technical dialect the third mood of the third figure is denominated,-
Some men are rapacious;
All men are rational animals;
Therefore some rational animals are rapacious.
Who does not perceive that "rational animals" is but a periphrasis for men?
It may be proper to subjoin one example at least, in negative syllogisms. The subsequent is one in Celarent, the second mood of the first figure:-
Nothing violent is lasting;
But tyranny is violent;
Therefore tyranny is not lasting.
Here a thing violent serves for the genus of which tyranny is a species; and nothing can be clearer than that it requires much less experience to discover whether shortness of duration be justly attributed to tyranny the species, than whether it be justly predicated of every violent thing. The application of what was said on the first example, to that now given, is so obvious that it would be losing time to attempt further to illustrate it.
Logicians have been at pains to discriminate the regular and consequential combinations of the three terms, as they are called, from the irregular and inconsequent. A combination of the latter kind, if the defect be in the form, is called a paralogism; if in the sense, a sophism; though sometimes these two appellations are confounded. Of the latter, one kind is denominated petitio principii, which is commonly rendered in English, a begging of the question, and is defined the proving of a thing by itself, whether expressed in the same or in different words, or which amounts to the same thing, assuming the proof the very opinion or principle proposed to be proved. It is surprising that this should ever have been by those artists styled a sophism, since it is in fact so essential to the art, that there is always some radical defect in a syllogism which is not chargeable with this. The truth of what I now affirm will appear to any one, on the slightest review of what has been evinced in the preceding part of this chapter.
The fourth and last observation I shall make on this topic is, that the proper province of the syllogistical science is rather the adjustment of our language, in expressing ourselves on subjects previously known, than the acquisition of knowledge in things themselves. According to M. du Marsais, "Reasoning consists in deducing, inferring, or drawing a judgment from other judgments already known; or rather in showing that the judgment in question has been already formed implicitly, insomuch that the only point is to develop it, and show its identity with some anterior judgment." Now I affirm that the former part of this definition suits all deductive reasoning, whether scientifical or moral, in which the principle deduced is distinct from, however closely related to, the principles from which the deduction is made. The latter part ofthe definition, which begins with the words or rather, does not answer as an explication of the former, as the author seems to have intended, but exactly hits the character of syllogistic reasoning, and indeed of all sorts of controversy merely verbal. If you regard only the thing signified, the argument conveys no instruction, nor does it forward us in the knowledge of things a single step. But if you regard principally the signs, it may serve to correct misapplications of them, through inadvertency or otherwise.
In evincing the truth of this doctrine, I shall begin with a simple illustration from what may happen to any one in studying a foreign tongue. I learn from an Italian and French dictionary, that the Italian word pecora corresponds to the French word brebis, and from a French and English dictionary, that the French brebis corresponds to the English sheep. Hence I form this argument,
Pecora is the same with brebis;
Brebis is the same with sheep;
Therefore pecora is the same with sheep.
This, though not in mood and figure, is evidently conclusive. Nay, more, if the words pecora, brebis, and sheep, under the notion of signs, be regarded as the terms, it has three distinct terms, and contains a direct and scientifical deduction from this axiom, "Things coincident with the same thing are coincident with one another." On the other hand, let the things signified be solely regarded, and there is but one term in the whole, namely, the species of quadruped denoted by the three names above mentioned. Nor is there, in this view of the matter, another judgment in all the three propositions, but this identical one, "A sheep is a sheep."
Nor let it be imagined that the only right application can be in the acquisition of strange languages. Every tongue whatever gives scope for it, inasmuch as in every tongue the speaker labours under great inconveniences, especially on abstract questions, both from the paucity, obscurity, and ambiguity of the words on the one hand; and from his own misapprehensions, and imperfect acquaintance with them on the other. As a man may, therefore, by an artful and sophistical use of them, be brought to admit, in certain terms, what he would deny in others, this disputatious discipline may, under proper management, by setting in a stronger light the inconsistencies occasioned by such improprieties, be rendered instrumental in correcting them. It was remarked above, that such propositions as these, "Twelve are a dozen," "Twenty are a score," unless considered as explications of the words dozen and score, are quite insignificant. This limitation, however, it was necessary to add; for those positions which are identical when considered purely as relating to the things signified, are nowise identical when regarded purely as explanatory of the names. Suppose that through the imperfection of a man's knowledge in the language, aided by another's sophistry, and perhaps his own inattention, he is brought to admit of the one term, what he would refuse of the other, such an argument as this might be employed,
Twelve, you allow, are equal to the fifth part of sixty;
Now a dozen are equal to twelve;
Therefore a dozen are equal to the fifth part of sixty.
I mark the case rather strongly, for the sake of illustration; for I am sensible, that in what regards things so definite as all names of number are, it is impossible for any one, who is not quite ignorant of the tongue, to be misled. But the intelligent reader will easily conceive, that in abstruse and metaphysical subjects, wherein the terms are often both extensive and indefinite in their signification, and sometimes even equivocal, the most acute and wary may be entangled in them.
In further confirmation of my fourth remark, I shall produce an example in Camestres, the second mood of the second figure:
All animals are mortal;
But angels are not mortal;
Therefore angels are not animals.
When the antagonist calls an angel an animal, it must proceed from one or other of these two causes, either from an error in regard to the nature of the angelic order, or from a mistake as to the import of the English word animal. If the first be the case,-namely, some erroneous opinion about angels, as that they are embodied spirits, generated and corruptible like ourselves,-it is evident that the forementioned syllogism labours under the common defect of all syllogisms. It assumes the very point in question. But if the difference between the disputants be, as it frequently happens, merely verbal, and the opponent uses the word animal as another name for living creature, and as exactly corresponding to the Greek term, arguments of this sort may be of service, for setting the impropriety of such a misapplication of the English name in a clearer light. For let it be observed, that though Nature hath strongly marked the principal differences to be found in different orders of beings, a procedure which hath suggested to men the manner of classing things into genera and species, this does not holdequally in every case. Hence it is, that the general terms in different languages do not always exactly correspond. Some nations, from particular circumstances, are more affected by one property in objects, others by another. This leads to a different distribution of things under their several names. Now, though it is not of importance that the words in one tongue exactly correspond to those in another, it is of importance that in the same tongue uniformity in this respect be, as much as is possible, observed. Errors in regard to the signs tend not only to retard the progress of knowledge, but to introduce errors in regard to the things signified. Now, by suggesting the different attributes comprised in the definition of the term, as so many mediums in the proof, an appeal is made to the adversary's practice in the language. In this way such mediums may be presented as will satisfy a candid adversary, that the application he makes of the term in question is not conformable to the usage of the tongue.
On the other hand, it is certain, that in matters of an abstract and complex nature, where the terms are comprehensive, indefinite, not in frequent use, and consequently not well ascertained, men may argue together eternally, without making the smallest impression on each other, not sensible, all the while, that there is not at bottom any difference between them, except as to the import of words and phrases. I do not say, however, that this is a consequence peculiar to this manner of debating, though perhaps oftener resulting from it, on account of its many nice distinctions, unmeaning subtleties, and mazy windings, than from any other manner. For it must be owned, that the syllogistic art has at least as often been employed for imposing fallacies on the understanding, as for detecting those imposed. And though verbal controversy seems to be its natural province, it is neither the only method adapted to such discussions, nor the most expeditious.
To conclude then; what shall we denominate the artificial system, or organ of truth, as it has been called, of which we have been treating? Shall we style it the art of reasoning? So honourable an appellation it by no means merits, since, as hath been shown, it is ill adapted to scientific matters, and for that reason never employed by the mathematician; and is utterly incapable of assisting us in our researches into nature. Shall we then pronounce it the science of logomachy, or in plain English, the art of fighting with words, and about words? And in this wordy warfare, shall we say that the rules of syllogizing are the tactics? This would certainly hit the matter more nearly; but I know not how it happens, that to call any thing logomachy or altercation, would be considered as giving bad names; and when a good use may be made of an invention, it seems unreasonable to fix an odious name upon it, which ought only to discriminate the abuse. I shall therefore only title it the scholastic art of disputation. It is the schoolmen's science of defence.
When all erudition consisted more in an acquaintance with words, and an address in using them, than in the knowledge of things, dexterity in this exercitation conferred as much lustre on the scholar, as agility in the tilts and tournaments added glory to the knight. In proportion as the attention of mankind has been drawn off to the study of nature, the honours of this contentious art have faded, and it is now almost forgotten. There is no reason to wish its revival, as eloquence seems to have been very little benefited by it, and philosophy still less.
Nay, there is but good reason to affirm, that there are two evils at least which it has gendered. These are, first, an itch of disputing on every subject, however uncontrovertible; the other, a sort of philosophic pride, which will not permit us to think that we believe any thing, even a self-evident principle, without a previous reason or argument. In order to gratify this passion, we invariably recur to words, and are at immense pains to lose ourselves in clouds of our own raising. We imagine we are advancing and making wonderful progress, while the mist of words in which we have involved our intellects, hinders us from discerning that we are moving in a circle all the time.
THE LOGIC MUSEUM Copyright (c) E.D.Buckner 2007.