omnes aliæ aperiuntur; et qua clausa, omnes aliæ LECT. clauduntur; cum qua quælibet, sine qua nulla.”“ € In II. rector of vices. modern times, we have systems of this science under the titles of Via ad Veritatem-Cynosura Veritatis? -Caput et Apex Philosophia-Heuristica, sive Introductio ad Artem Inveniendi, &c. But it was not As the coronly viewed as an instrument of discovery, it was intellectual likewise held to be the infallible corrector of our intellectual vices, the invigorator of our intellectual imbecility. Hence some entitled their Logics,-The Medicine of the Mind, The Art of Thinking," The Lighthouse of the Intellect, The Science Teaching the Right Use of Reason,' &c. &c. Now in all this there is a mixture of truth and error. To a certain extent, and in certain points of view, Logic is the organ of philosophy, the criterion of truth, and the corrector of error, and in others it is not. spect Logic ment of the In reference to the dispute whether logic may with In what repropriety be called the instrument, the organon of is an instruthe other sciences, the question may be at once solved sciences. by a distinction. One science may be styled the instrument of another, either in a material or in a a Mauritii Expositio Quæstionum Doctoris Subtilis in quinque Universalia Porphyrii, Quæst. i. (Scoti Opera, Lugd., 1639, tom. i. p. 434). Mauritius refers to St Augustin as his authority for the above quotation. It slightly resembles a passage in the De Ordine, L. ii. c. 13.-ED. B Gundling, Via ad Veritatem Moralem, Halæ, 1713. Darjes, Via ad Veritatem, Jenae, 1764 (2d edit.)— ED. P. Laurembergius, Cynosura Bona Mentis 8. Logica, Rostoch, 1633. R. Loenus, Cynosura Rationis, Arnhem, 1667.-ED. 8 See Krug, Logik, § 9, p. 23, from whom several of the above definitions were probably taken.-ED. ← Gunner, Ars Heuristica Intellectualis, Lipsiæ, 1756. Trattato di Messer Sebastiano Erizzo, dell' Istrumento et Via Inventrice de gli antichi nelle scientie, Venice, 1554.-ED. Tschirnhausen, Medicina Mentis, sive Artis Inveniendi Præcepta Generalia, Amst., 1687. Lange, Medicina Mentis, Halæ, 1703.-ED. n L'Art de Penser, commonly known as the Port Royal Logic. Several other works have appeared under the same title.-ED. • Grosserus, Pharus intellectus, sive Watts, Logic, or the Right Use of II. LECT. formal point of view. In the former point of view, one science is the organ of another when one science determines for another its contents or objects. Thus Mathematics may be called the material instrument of the various branches of physical science; Philology, or study of the languages, Latin, Greek, Hebrew, Chaldee, &c., with a knowledge of their relative history,-constitutes a material instrument to Christian Theology; and the jurist, in like manner, finds a material instrument in a knowledge of the history of the country whose laws he expounds." Thus also Physiology, in a material point of view, is the organon of Medicine; Aristotle has indeed well said that medicine begins where the philosophy of nature leaves off. In the latter point of view, one science is the organon of another, when one science determines the scientific form of another. Now, as it is generally admitted that Logic stands in this relation to the other sciences, as it appertains to Logic to consider the general doctrine of Method and of systematic construction, in this respect Logic may be properly allowed to be to the sciences an instrument, but only. a formal instrument." Logic not properly an covery. In regard to the other titles of honour, Logic canart of dis not with propriety be denominated a [Heuretic or] Art of Discovery. "For discovery or invention is not to be taught by rules, but is either the free act of an original genius, or the consequence of a lucky accident, which either conducts the finder to something unknown, or gives him the impulse to seek it out. Logic can at best only analytically teach how to discover, that is, by the development and dismemberment of a See Genovesi, Elementa Artis Logico-Critica, L. i. c. iii. p. 41, B De Sensu et Sensili, c. i. y Krug, Logik, § 9, p. 23; Cf. Platner, Philosophische Aphorismen, Part i. p. 23, ed. 1793.-ED. II. what is already discovered. By this process there LECT. is nothing new evolved, and our knowledge is not amplified; all that is accomplished is a clearer and distincter comprehension of the old ;-our knowledge is purified and systematised."" It is well observed by Antonius, in Cicero :-" Nullum est præceptum in hac arte quomodo verum inveniatur, sed tantum est, quomodo judicetur." Logic is thus not creative; it is only plastic, only formative, in relation to our knowledge. 66 sense Logic - can be styled the the mind. Again, "Logic cannot with propriety be styled the In what medicine of the mind, at least without some qualifying adjective, to show that the only remedy it can medicine of apply is to our formal errors, while our material errors lie beyond its reach. This is evident. Logic is the science of the formal laws of thought. But we cannot, in limiting our consideration to the laws of formal thinking, investigate the contents,-the matter, of our thought. Logic can, therefore, only propose to purge the understanding of those errors which lie in the confusion and perplexities of an inconsequent thinking. This, however, it must be confessed, is no radical cure, but merely a purification of the understanding. In this respect, however, and to this extent, Logic may justly pretend to be the medicine of the mind, and may, therefore, in a formal relation, be styled, as by some logicians it has in fact been, Catharticon intellectus. "By these observations the value of Logic is not depreciated; they only prepare us to form an estimate of its real amount. Precisely, in fact, as too much was promised and expected from this study, did it lose in credit and esteem." » γ a Krug, Logik, § 9, p. 24.-ED. Cf. [Richter, Logik, p. 83 et seq.] B De Oratore, ii. 38.-ED. y Krug, Logik, § 9, pp. 24-6.-ED. Cf. [Richter, Logik, p. 85.] tion. LECTURE III. INTRODUCTION. LOGIC-II. ITS UTILITY.-III. ITS DIVISIONS-SUBJEC- LECT. THE last Lecture was occupied with the consideration III. of the latter part of the introductory question,-What Recapitula is Logic? and with that of the first part of the second, -What is its Utility?—In the Lecture preceding the last, I had given the definition of Logic, as the science of the laws of thought as thought, and, taking the several parts of this definition, had articulately explained, 1o, What was the meaning and history of the word Logic; 2, What was the import of the term science, the genus of Logic; and, 3°, What was signified by laws of thought as thought, the object-matter of Logic. This last I had considered under three heads, explaining, 1o, What is meant by thought; 2°, What is meant by thought as thought; and, 3o, What is meant by laws of thought as thought. It was under the last of these heads that the last Lecture commenced. I had, in the preceding, shown that the form of thought comprises two kinds of phænomena, given always in conjunction, but that we are able by abstraction and analysis to discriminate them from each other. The one of these classes comprehends what is contingent, the other what is necessary, in the manifestations of thought. The necessary element is the peculiar and III. exclusive object of Logic; whereas the phænomena of LECT. thought and of mind in general are indiscriminately proposed to Psychology. Logic, therefore, I said, is distinguished from the other philosophical sciences by its definition, as the science of the necessary form of thought. This, however, though a full and final definition, is capable of a still more explicit enunciation; and I showed how we are entitled to convert the term necessary into the term laws, and, in doing so, I took the opportunity of explaining how, the necessity of a mental element being given, there is also implicitly given the four conditions, 1°, That it is subjective; 2°, That it is original; 3°, That it is universal; and, 4°, That it is a law. The full and explicit definition of Logic, therefore, is, the science of the Laws of Thought as Thought; or, the science of the Laws of the Form of Thought; or, the science of the Formal Laws of Thought:-these being only three various expressions of what is really the same. Logic being thus defined, I gave a brief and general retrospect of the history of opinion in regard to the proper object and domain of Logic, and showed how, though most logicians had taken speculatively, and in general, a very correct view of the nature of their science, they had not carried this view out into application, by excluding from the sphere of Pure or Abstract Logic all not strictly relative to the form of thought, but had allowed many doctrines relative merely to the matter of thought to complicate and to deform the science. I then called attention to the opinions of the author whom I recommend to your attention, and showed that Dr Whately, in his statements relative to the object-matter of Logic, is vague and obscure, errone |