LOGIC
The Atlas.][April 12, 1829.
Much has been said and written of the importance of logic to the advancement of truth and learning, but not altogether convincingly. Its use is chiefly confined by some to being a guide to the mind when first feeling its way out of the night of ignorance and barbarism, or a curb to the wilful and restive spirit that is a rebel to reason and common sense. But the extent of the benefit in either case may be doubted; since the rude and uninstructed will not submit to artificial trammels, or get up into thisgo-cartof the understanding, and the perverse and obstinate will jump out of it whenever their prejudices or passions are wound up to a height to make its restraints necessary. The wilful man will have his way in spite of the dictates of his reason or the evidence of his senses either. The study of logic has been compared to the getting ready and sharpening the tools with which the mind works out the truth; but all that is of value in it is more like the natural use of our hands, or resembles the mould in which truth must be cast, and which is born with us, rather than an external instrument with which it must be fashioned; for all syllogisms reduce themselves either to identical propositions, or to certain forms and relations of ideas in the understanding, which are antecedent to, and absolutely govern, our conclusions with the rules for drawing them. The mind cannotmake an instrument to make truth, as it contrives an instrument to make a certain object; for in the latter case, the object depends upon the act and will of the mind; but in the former, the mind is passive to the impression of given objects upon it, and this depends on certain laws over which it has itself no control. Logic at best only lays down the rules and laws by which our reason operates; but it must operate according to those rules and laws equally whether they are adverted to or not, or they could not be laid down as infallible. Truth is, in a word, the shape which ourideas take in the moulds of the understanding, just as the potter’s clay derives its figure (whether round or square) from the mould in which it is cast. Thus, if we are told that one wine-glass is less than another, and that the larger wine-glass is less than a third, we know that the third wine-glass is larger than the first, without either comparing them or having any general rule to prove it by. We can no more conceive it otherwise, or do away that regular gradation and proportion between the objects so defined and characterised, than we can imagine the same thing to grow bigger and become less at the same time. Reasoning is allowed (at least by the schoolmen and the Universities of Oxford and Cambridge, though not by our wise sceptical moderns) to be the linking of one judgment on to two others:thisandthatbeing given, why then something else follows. Thus, suppose two roads to take a diverging direction, you are sure, without measuring, that the farther you go in the one, the farther you get from the other. You know that you advance: youinferthat you recede. Now the difficulty lies here—if the premises are the same with the conclusion, it amounts only to an identical proposition: if they are different, what is the connection between them? But in the example just given, there are two circumstances, or properties, stated at the outset of the question,viz.—not merely the existence, but the direction, of the road; and to sustain the inference, all that seems necessary is, that both these circumstances should be borne in mind. For if the road do not continue todiverge, the conclusion will not hold good; and if it still continue to diverge, what is this but saying, not only that it advances, but that it advances in a direction which, by the supposition, carries it farther at every step from the former road? That is, two things are affirmed of a given object; the mind sets out with a complex proposition, and what it has to do is not to forget one half of it by the way. It would be long enough before the abstract idea of a road would imply its distance from another; but it would also be hard if a diverging road—that is, a road that recedes while it advances—did not recede. A mathematical line and its direction are not two things, like the feet of a pair of compasses—that while the line is moving one way, the direction may be going astray in another—but mutually implied and inseparably connected together in nature or the understanding—let therealistsoridealistsdetermine which they please. Or, as the wise man said to the daughter of King Cophetua, ‘That which is, is; for what isthatbutthat, andisbutis?’[58]The worstof the matter is, that the most important conclusions are not to be so easily enclosed in pews and forms of words and definitions; and that to catch the truth as it flies, is as nice a point as hedging the cuckoo: though they say that its wings have been lately clipped and a pound built for it somewhere in Westminster. Not to proceed farther in this subject, and get ‘over shoes, over boots’ in the mire of metaphysics, we shall conclude this article with what we meant to state at the commencement of it, to wit—that the commonest form of the syllogism is the worst of all, being a downright fallacy andpetitio principii. It consists in including the individual in the species, and runs thus: ‘All men are mortal; John is a man; therefore John is mortal.’ Let any one deny this at his peril; but what is, or can be gained by such parroting? The first branch of the premises takes for granted and supposes that you already know all that you want to prove in the conclusion. For before you are entitled to assert roundly that all men are mortal, you must know this of John in particular, who is a man, which is the point you are labouring to establish; or, if you do not know this of every individual man, and of John among the rest, then you have no right to make such a sweeping general assertion, which falls to the ground of itself. Either the premises are hasty or false, and the conclusion rotten that way; or if they be sound, and proved as matter-of-fact to the extent which is pretended, then you have anticipated your conclusion, and your syllogism is pedantic and superfluous. In fact, this form of the syllogism is an unmeaning play upon words, or resolves itself into the merely probable or analogical argument, that because all other menhave died, John, who is one of of them,will diealso. The inference relating to historical truth, and founded on the customary connection between cause and effect, is very different from logical proof, or the impossibility of conceiving of certain things otherwise than as inseparable. Suppose I see a row of pillars before me, and that I chuse to affirm—‘Those hundred pillarsare all of white marble; the pillar directly facing me is one of the hundred; therefore that pillar is also of white marble’—would not this be arrant trifling both with my own understanding and with that of any one who had patience to hear me? But if I were to see a number of pillars resembling each other in outward appearance, and on examining all of them but one, found them of white marble and concluded that that one was of white marble too, there would be some common sense in this, but no logic. The mind, however, has a natural bias to wrap up its conclusions (of whatever kind or degree) in regular forms of words, and to deposit them in an imposing framework of demonstration; it prefers the shadow of certainty to the substance of truth and candour; and will not, if it can help it, leave a single loop-hole for doubt to creep in at. Hence the tribe of logicians, dogmatists, and verbal pretenders of all sorts.