employed, without previously analyzing and resolving them into their simple elements; as well might it be imagined that, to speak grammatically, means, to parse every sentence we utter. The chemist (to pursue the illustration) keeps by him his tests and his method of analysis, to be employed when any substance is offered to his notice, the composition of which has not been ascertained, or in which adulteration is suspected. Now a fallacy may aptly be compared to some adulterated compound; "it "consists of an ingenious mixture of truth and "falsehood, so entangled,--so intimately blended, that the falsehood is (in the chemical

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phrase) held in solution: one drop of sound "logic is that test which immediately disunites them, makes the foreign substance visible, "and precipitates it to the bottom." *

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dictum.

But to resume the investigation of the prin- Aristotle's ciples of reasoning: the maxim resulting from the examination of a syllogism in the foregoing form, and of the application of which, every valid argument is in reality an instance, is, "that whatever is predicated (i. e. affirmed or

*This excellent illustration is cited from a passage in an anonymous pamphlet, "An Examination of Kett's Logic." The author displays, though in a hasty production, great reach of thought, as well as knowledge of his subject.

denied) universally, of any class of things, may be predicated, in like manner, (viz. affirmed or denied) of any thing comprehended in that class." This is the principle, commonly called the dictum de omni et nullo, for the establishIment of which we are indebted to Aristotle, and which is the keystone of his whole logical system. It is not a little remarkable that some, otherwise judicious writers, should have been so carried away by their zeal against that philosopher, as to speak with scorn and ridicule of this principle, on account of its obviousness and simplicity; though they would probably perceive at once, in any other case, that it is the greatest triumph of philosophy to refer many, and seemingly very various, phenomena to one, or a very few, simple principles; and that the more simple and evident such a principle is, provided it be truly applicable to all the cases in question, the greater is its value and scientific beauty. If, indeed, any principle be regarded as not thus applicable, that is an objection to it of a different kind. Such an objection against Aristotle's dictum, no one has ever attempted to establish by any kind of proof; but it has often been taken for granted; it being (as has been stated) very commonly supposed, without examination, that the syllogism is a distinct kind of argument, and that the rules of it accordingly do not

apply, nor were intended to apply, to all reasoning whatever. Under this misapprehension, Dr. Campbell* labours with some ingenuity, and not without an air of plausibility, to show that every syllogism must be futile and worthless, because the premises virtually assert the conclusion: little dreaming, of course, that his objections, however specious, lie against the process of reasoning itself, universally; and will therefore, of course, apply to those very arguments which he is himself adducing.

It is much more extraordinary to find another eminent author adopting, expressly, the very same objections, and yet distinctly admitting (within a few pages) the possibility of reducing every course of argument to a series of syllogisms.

The same writer brings an objection against the Dictum of Aristotle, which it may be worth while to notice briefly, for the sake of setting in a clearer light the real character and object of that principle. Its application being, as has been seen, to a regular and conclusive syllogism, he supposes it intended to prove and make evident the conclusiveness of such a syllogism; and remarks how unphilosophical it is to attempt giving a demonstration of a * "Philosophy of Rhetoric."

+Dugald Stewart: Philosophy, vol. ii.

D

demonstration. would be just, if we could imagine the logician's object to be, to increase the certainty of a conclusion which we are supposed to have already arrived at by the clearest possible mode of proof. But it is very strange that such an idea should ever have occurred to one who had even the slightest tincture of natural philosophy for it might as well be imagined that a natural philosopher's or a chemist's design is to strengthen the testimony of our senses by à priori reasoning, and to convince us that a stone when thrown will fall to the ground, and that gunpowder will explode when fired; because they show that according to their principles those phenomena must take place as they do. But it would be reckoned a mark of the grossest ignorance and stupidity not to be aware that their object is not to prove the existence of an individual phenomenon, which our eyes have witnessed, but (as the phrase is) to account for it: i. e. to show according to what principle it takes place ;—to refer, in short, the individual case to a general law of nature. The object of Aristotle's dictum is precisely analogous: he had, doubtless, no thought of adding to the force of any individual syllogism; his design was to point out the general principle on which that process conducted which takes place in each syllogism.

And certainly the charge

is

*

And as the Laws of nature (as they are called) are in reality merely generalized facts, of which all the phenomena coming under them are particular instances; so, the proof drawn from Aristotle's dictum is not a distinct demonstration brought to confirm another demonstration, but is merely a generalized and abstract statement of all demonstration whatever; and is, therefore, in fact, the very demonstration which, (mutatis mutandis) accommodated to the various subject-matters, is actually employed in each particular case.

statement of argument in

In order to trace more distinctly the different The dictum, a steps of the abstracting process, by which any retract. particular argument may be brought into the most general form, we may first take a syllogism stated accurately and at full length, such as the example formerly given, "whatever exhibits marks of design, &c.," and then somewhat generalize the expression, by substituting (as in Algebra) arbitrary unmeaning symbols for the significant terms that were originally used; the syllogism will then stand thus; every B is A; C is B; therefore C is A." The reasoning is no less evidently valid when thus stated, whatever terms A, B, and C, respectively may be supposed to stand for; such terms may indeed be inserted as to make all or some of

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