Leibnitz. Wolf. LECT. tradiction, but, against Aristotle, he maintains, that V. the principle of Identity, and not the principle of Contradiction, is the one absolutely first. The formula in which Andreas expressed it was, Ens est ens. Subsequently to this author, the question concerning the relative priority of the two laws of Identity and of Contradiction became one much agitated in the schools; though there were also found some who asserted to the law of Excluded Middle this supreme rank." Leibnitz, as I have said, did not always distinguish the principles of Identity and of Contradiction. By Wolf the former was styled the principle of Certainty, (principium Certitudinis) ; but he, no more than Leibnitz himself, sufficiently discriminated between it and the law of Contradiction. This was, however, done by Baumgarten, another distinguished follower of Leibnitz, and from him it received the name of the principle of Position, that is, of Affirmation or Identity, (principium Positionis sive Identitatis),—the name by which it is now universally known. This principle has found greater favour in the eyes of the absolutist philosophers, than those of Contradiction and Excluded Middle. By Fichte and Schelling it Schelling. has been placed as the primary principle of all philosophy. Hegel alone subjects it, along with the other laws of thought, to a rigid but fallacious criticism; and rejects it along with them, as belonging to that lower sphere of knowledge, which is conversant only with the relative and finite. Baum garten. Fichte and Hegel. a [Alex. de Ales, In Arist. Metaph., iv. t. 9.] Compare Suarez, Disp. Metaph., Disp. iii. § 3. Alexander professes to agree with Aristotle in giving the first place to the principle of Contradiction, but, in fact, he identifies it with that of Excluded Middle, de quovis affirmatio vel negatio.-Ed. See Fichte, Grundlage der ge- V. Reason and Recognised and Aris The fourth law, that of Reason and Consequent, LECT. which stands apart by itself from the other three, was, like the laws of Contradiction and Excluded Middle, Law of recognised by Plato." He lays it down as a postu- Consequent. late of reason, to admit nothing without a cause; and by Plato the same is frequently done by his scholar Aristotle. totle. Both, however, in reference to this principle, employ the ambiguous term cause, (airía, aitiov). Aristotle, indeed, distinguishes the law of Reason, as the ideal principle 'Apx Tñs of knowledge, (apxǹ Tîs yvwσews, principium cognos- "Apx ris cendi), from the real principle of Production, (apy TŶS YEVÉσEWS. yevéσews, principium fiendi,-principium essendi). By Cicero the axiom of reason and consequent was, Cicero. in like manner, comprehended under the formula, nihil sine causa,—a formula adopted by the school- The Schoolmen; although they, after Aristotle, distinguished under it the ratio essendi, and the ratio cognoscendi. γνώσεως. γενέσεως. men. called atten of Sufficient In modern times, the attention of philosophers was Leibnitz called to this law by Leibnitz, who, on the two prin- tion to Law ciples of Reason and of Contradiction, founded the Reason. whole edifice of his philosophy. Under the latter law, as I have mentioned, he comprehended, however, the principle of Identity; and in the former he did not sufficiently discriminate, in terms, the law of Causality, as a real principle, from the law of Reason, properly so called, as a formal or ideal principle. To this axiom he gave various denominations,-now calling it the principle of Determining Reason, now the principle of Sufficient Reason, and now the principle of Convenience or Agreement, (convenientia); making it, in its real relation, the ground of all existence, in a Philebus, p. 26.-ED. B E. g., Anal. Post., ii. 16; Phys., ii. 3; Metaph, i. 1, 3; Rhet., ii. 23.ED. y Metaph., iv. (v.) 1.-Ed. 8 De Divinatione, ii. c. 28.-ED. V. LECT. its ideal, the ground of all positive knowledge. On this subject there was a celebrated controversy between Leibnitz and Dr Samuel Clarke, a controversy on this, as on other points, eminently worthy of your study. The documents in which this controversy is contained, were published in the English edition under the title, A collection of Papers which passed between the late learned Mr Leibnitz and Dr Clarke, in the years 1715 and 1716, relating to the Principles of Natural Philosophy and Religion, London, 1717." Wolf. Discussion regarding Wolf, the most distinguished follower of Leibnitz, employs the formula,-"Nothing is without a sufficient reason why it is, rather than why it is not; that is, if anything is supposed to be, (ponitur esse), something also must be supposed, whence it may be understood why the same is rather than is not." He blames the schoolmen for confusing reason, (ratio), with cause, (causa): but his censure equally applies to his master Leibnitz as to them and Aristotle; for all of these philosophers, though they did not confound the two principles, employed ambiguous terms to denote them. The Leibnitzian doctrine of the universality of the the Leib- law of Sufficient Reason, both as a principle of existdoctrine of ence and of thought, excited much discussion among Sufficient the philosophers, more particularly of Germany. In nitzian the law of Reason. the earlier half of the last century, some controverted the validity of the principle, others attempted to restrict it. Among other arguments, it was alleged, by a See especially, Leibnitz's Second Letter, p. 20, in which the principle of Contradiction or Identity is assumed as the foundation of all mathematics and that of Sufficient Reason as the foundation of natural philosophy. ED. B See Fischer's Logik, [§ 59, p. 38, ed. 1838. Compare Wolf, Ontologia, §§ 70, 71.—ED.] y As Feuerlin and Daries. See Bachmann, Logik, p. 56, Leipsig, 1828; Cf. Degerando, Hist. Comp. des Syst. de Phil., t. ii. p. 145, ed. 1804.-ED. V. the advocates of the former opinion, if the principle LECT. be admitted, that everything must have a sufficient reason why it is, rather than why it is not,-on this hypothesis, error itself will have such a reason, and, therefore, must cease forthwith to be error." Many philosophers, as Wolf and Baumgarten, endeavoured to demonstrate this principle by the principle of Contradiction; while others, with better success, showed that all such demonstrations were illogical.R In the more recent systems of philosophy, the universality and necessity of the axiom of Reason has, with other logical laws, been controverted and rejected by speculators on the absolute." a See Bachmann, Logik, p. 56. With the foregoing history of the laws of Thought, compare the same author, Logik, § 18-31.-ED. B [Kiesewetter, Allgemeine Logik, P. i. p. 57]; |; compare Lectures on Metaphysics, ii. pp. 396, 397, notes.-ED. y [On principle of Double Negation as another law of Thought, see Fries, Logik, § 41, p. 190; Calker, Denklehre oder Logik und Dialektik, § 165, p. 453; Beneke, Lehrbuch der Logik, § 64, p. 41.] VI. Recapitulation. LECTURE VI. STOICHEIOLOGY. SECTION I.-NOETIC. THE FUNDAMENTAL LAWS OF THOUGHT THEIR LECT. HAVING concluded the Introductory Questions, we entered, in our last Lecture, upon our science itself. The first part of Pure Logic is the Doctrine of Elements, or that which considers the conditions of mere or possible thinking. These elements are of two kinds, -they are either the fundamental laws of thought as regulating its necessary products, or they are the products themselves as regulated by those laws. The fundamental laws are four in number,-the law of Identity, the law of Contradiction, the law of Excluded Middle, the law of Reason and Consequent." The products of thought are three,-1°, Concepts or Notions; 2°, Judgments; and, 3°, Reasonings. In our last Lecture, we considered the first of these two parts of the doctrine of elements, and I went through the general explanation of the contents and import of the four laws, and their history. Without recapitulating what was then stated, I shall now proceed to certain general observations, which may be suggested General observations in relation in relation to the four laws. And, first of all, I may remark, that they naturally to the four fall into two classes. The first of these classes con-ED. a See, however, above, p. 86, note a.— |