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CHAP. to be employed sparingly.102 When any proposi.. tion is so obvious, that it cannot fail to occur spontaneously, it would savour of the rustic or the pedant10 to declare it: but expressed or understood, the elements of syllogism are essential to all demonstration, for all reasoning whatever, implies a subject about which we reason, premises from which we reason, and a conclusion that is drawn from them.104
If Mr. S. had not too much despised logic, to be a proficient in that art, he would not have found fault with Aristotle's phraseology in dividing syllogisms into demonstrative and dialectical. He says, "For the sake of those who have not previously turned their attention to Aristotle's logic, it is necessary, before proceeding farther, to take notice of a peculiarity, (and as appears to me, an impropriety) in the use of the epithets demonstrative and dialectical, to mark the distinction between the two great classes into which he divides syllogisms; a mode of speaking which, according to the common use of language, would seem to imply, that one species of syllogism may be more conclusive and cogent than another. That this is not the case, is almost self-evident; for if a syllogism be perfect in form, it must of necessity be not only conclusive, but demonstratively conclusive. Nor is this, in fact, the idea which Aris
102 Rhetoric, l. iii. cap. 18. p. 389. edit. Buhle. et pasim.
109 I have resolved the epithet popтikov because it implies both notions.
104 Analyt. Poster. l. 1. c. 10. p. 270. edit. Buhle.
105 Elements, vol. ii. p. 249.
totle himself annexed to the distinction; for he CHAP. tells us, that it does not refer to the form of syllogisms, but to the matter; or, in plainer language, to the degree of evidence accompanying the premises on which they proceed. In the two books of his last Analytics, accordingly, he treats of syllogisms that are said to be demonstrative, because their premises are certain; and in his topics of what he calls dialectical syllogisms, because their premises are only probable. Would it not have been a clearer and juster mode of stating this distinction, to have applied the epithets demonstrative and dialectical to the truth of the conclusions resulting from these two classes of syllogisms, instead of applying them to the syllogisms themselves? The phrase demonstrative syllogism certainly seems, at first sight, to express rather the complete and necessary connection between the conclusion and the premises, than the certainty or the necessity of the truths which the premises assume."106 This reason is a very illogical one. In every legitimate syllogism, the conclusion is indeed necessarily connected with the premises; but, as every syllogism must consist of premises, as well as of a conclusion, nothing more than a dialectical or probable syllogism can be the result of dialectical or probable premises.
A demonstrative syllogism, therefore, requires premises that are necessary and certain; since, in the words of Aristotle, these qualities could not
106 Elem. vol. ii. p. 250.
CHAP. be ascribed to the conclusion, unless they belonged to the premises which are its "causes." 107 These observations are not made with a view merely to vindicate the propriety of one phraseology in preference to another. They are made rather to obviate an error into which many have fallen with respect to Aristotle's logic, in confining it to the rules by which, from given premises, we may infer a legitimate conclusion. The principal concern of logic, on the contrary, is with the premises themselves: to discover the certainty or various degrees of probability on which they rest, and to omit none of the premises that bear on the subject; since our errors, as I had before occasion to show, proceed less frequently from illogical inference, than from narrowness of comprehension and rashness of assumption, 108
107 How justly did Sam. Johnson suspect, that the Peripatetic Logic had been condemned without a candid trial. See Johnson's Works, vol. ii. Preface to the Preceptor.
108 See New Analysis, p. 91. comp. p. 234.
Character of Mr. Stewart's Writings. - The Paris and
In the former chapter I obviated every one of CHAP. Mr. Stewart's objections, whether against the doctrines of my author, or my own inter- Character pretation of them. The character of the ob- Stewart's jector, and the rank which he holds in the writings. republic of letters, merited this complete ex
CHAP. amination. While professor in the university of Edinburgh, Mr. Stewart was regarded (and I think most justly) as the principal ornament of that illustrious school. His writings also, are in high estimation; most readers may derive profit from them, and all receive much "rational entertainment;" for, being well acquainted with the French and English metaphysicians, many of them men of genius and fancy, from Hobbes and Des Cartes downward to the writers of the present day, Mr. Stewart has selected from them with taste and judgment, and embodied, by way of citation, into his own works, many of their most ingenious remarks and most brilliant passages. The object of his own philosophy, is "to ascertain the simple and uncompounded faculties, or principles, of which the mind consists; and his method of prosecuting this study is the way of observation and experiment recommended by Lord Bacon, for ascertaining the properties of bodies."1 Whatever may be thought of this undertaking, or of his own and Dr. Reid's success in conducting it, Mr. Stewart will be acknowledged to have embellished many parts of his subject, by natural and apt comparisons, and to have adorned the whole with a style, less attic and various indeed than that of Locke or Hume, but clear, flowing, and harmonious. To me it appears, that the authors on whom he has formed his taste, are not of native growth; much less has he looked back to Greece or Rome; France should seem to have 1 Stewart's Elements, passim.