"This book," the author says in his preface, "makes no pretence of giving to the world a new theory of our intellectual operations. Its claim to attention, if it possess any, is grounded on the fact, that it is an attempt not to supersede, but to embody and systematize, the best ideas which have been either promulgated on its subject by speculative writers, or conformed to by accurate thinkers in their scientific enquiries.
"To cement together the detached fragments of a subject, never yet treated as a whole; to harmonize the true portions of discordant theories, by supplying the links of thought necessary to connect them, and by disentangling them from the errors with which they are always more or less interwoven—must necessarily require a considerable amount of original speculation. To other originality than this, the present work lays no claim. In the existing state of the cultivation of the sciences, there would be a very strong presumption against any one who should imagine that he had effected a revolution in the theory of the investigation of truth, or added any fundamentally new process to the practice of it. The improvement which remains to be effected in the methods of philosophizing, [and the author believes that they have much need of improvement,] can only consist in performing, more systematically and accurately, operations with which, at least in their elementary form, the human intellect, in some one or other of its employments, is already familiar."
Such is the manly and modest estimate which the author makes of his own labours, and the work fully bears out the character here given of it. No one capable of receiving pleasure from the disentanglement of intricacies, or the clear exposition of an abstruse subject; no one seeking assistance in the acquisition of distinct and accurate views on the various and difficult topics which these volumes embrace—can fail to read them with satisfaction and with benefit.
To give a full account—to give any account—of a work which traverses so wide a field of subject, would be here a futile attempt; we should, after all our efforts, merely produce a laboured and imperfect synopsis, which would in vain solicit the perusal of our readers. What we purpose doing, is to take up, in the order in which they occur, some of the topics on which Mr Mill has thrown a new light, or which he has at least invested with a novel interest by the view he has given of them. And as, in this selection of topics, we are not bound to choose those which are most austere and repulsive, we hope that such of our readers as are not deterred by the very name of logic, will follow us with some interest through the several points of view, and the various extracts we shall present to them.
The Syllogism.—The logic of Induction, as that to which attention has been least devoted, which has been least reduced to systematic form, and which lies at the basis of all other modes of reasoning, constitutes the prominent subject of these volumes. Nevertheless, the old topic of logic proper, or deductive reasoning, is not omitted, and the first passage to which we feel bound, on many accounts, to give our attention, is the disquisition on the syllogism.
Fortunately for us it is not necessary, in order to convey the point of our author's observations upon this head, to afflict our readers with any dissertation upon mode or figure, or other logical technicalities. The first form or figure of the syllogism (to which those who have not utterly forgotten their scholastic discipline will remember that all others may be reduced) is familiar to every one, and to this alone we shall have occasion to refer.
"All men are mortal.
A king is a man;
Therefore a king is mortal."
Who has not met—what young lady even, though but in her teens, has not encountered some such charming triplet as this, which looks so like verse at a distance, but, like some other compositions, approximates nothing the more on this account to poetry? Who has not learnt from such examples what is a major, what a middle term, and what the minor or conclusion?
As no one, in the present day, advises the adoption, in our controversies, of the syllogistic forms of reasoning, it is evident that the value of the syllogism must consist, not in its practical use, but in the accurate type which it affords of the process of reasoning, and in the analysis of that process which a full understanding of it renders necessary. Such an analysis supplies, it is said, an excellent discipline to the mind, whilst an occasional reference to the form of the syllogism, as a type or model of reasoning, insures a steadiness and pertinency of argument. But is the syllogism, it has been asked, this veritable type of our reasoning? Has the analysis which would explain it to be such, been accurately conducted?
Several of our northern metaphysicians, it is well known—as, for example, Dr Campbell and Dugald Stewart—have laid rude hands upon the syllogism. They have pronounced it to be a vain invention. They have argued that no addition of knowledge, no advancement in the acquisition of truth, no new conviction, can possibly be obtained through its means, inasmuch as no syllogism can contain any thing in the conclusion which was not admitted, at the outset, in the first or major proposition. The syllogism always, say they, involves a petitio principii. Admit the major, and the business is palpably at an end; the rest is a mere circle, in which one cannot advance, but may get giddy by the revolution. According to the exposition of logicians themselves, we simply obtain by our syllogism, the privilege of saying that, in the minor, of some individual of a class, which we had said, in the major, already of the whole class.