Thus we are taken back to the early Greek philoso- phers for the first formal discussions of what is now uni- versally denominated Logic. They, in successive gen- erations, developed with more or less clearness its prin-
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cipal elements. Socrates illustrated induction ; Euclid, deduction. Plato treated of mental images as the re- sults of sensation, of notions as the pro(hict of the un- derstanding, and of ideas as the product of reason. Aris- totle formulated syllogisms, anil defined their principal laws. He taught analysis. He devised a system of categories. He enumerated the five predicables, genus, species, difference, property, and accident. In short, he reduced to a system tlie fragmentary discoveries in the philosophy of mind of those who had gone before him, and embodied them in works destined to exert a great influence upon after ages. Like many other great men, Aristotle was but indifferently appreciated by his con- temporaries. Even after his death, his logical system produced but little intjuence upon his countrymen the Greeks. Several of the Christian fathers, however, give evidence of having profited by its study, and of de- siring to use the knowledge they had thus acquired in propagating the truth of Christianity. Justin Martyr, Tatian, Athenagoras, Clement, and otlicrs, both used and defended such dialectics as they had learned in the Gre- cian schools. On the other hand, as the same style of dialectics had been closely identified with the pernicious vagaries of heathen philosophy, Tertullian, Iremvus, Ar- nobius, and Lactantius considered its use as unfavorable to the interests of Christianity, and destructive of true science and wisdom. Augustine also wrote in the same spirit against the academicians.
Nevertheless, speculative studies held a relative prom- inence in the learning of Greece and Home during the early Christian centuries ; and when, owing to the bar- barian irruptions, learning and civilization declined, di- alectical science remained in more general cultivation than almost any other of the higher species of knowl- edge. Having its subject matter in the human mind, it was not dependent for perpetuity upon those external circumstances which influenced the conditions of gen- eral literature. Boethius, who has been called the last of the ancient philosophers, and the connecting link be- tween the classical and the mediteval age, made a trans- lation of Aristotle's categories into Latin. His contem- poraries of the (jth century, Cassiodorus.Capella, and Isi- dore of Seville, together with several Byzantine ivriters, e. g, George Pachymera, Theodorus Metachita, and Mi- chael Psellus, formed meagre compendiums of logic and rhetoric, without any clear distinction between the two. These manuals superseded or rather substituted the use of the ancient authors on both these subjects, and, im- perfect as they were, became the oracles of that long and dismal period in which the trivium (grammar, log- ic, and rhetoric) and quadrivium (music, arithmetic, geometry, and astronomy) were the chief topics of study and instruction. The ignorance consequent upon such a condition of things continued for the long period of five centuries without material variation.
In the latter part of the 11th centun,^ commenced a period of literary awakening known to history as the first a.'ra of scholasticism. See Scholasticism. This movement was characterized by attempts to construct systems of theology on the traditional basis with strict dialectical form and method. Paris was the chief seat of the movement. Anselm, aii abbot at Bee in 1078, and late in life an archbishop of Canterbury, made the first vigorous attempt in harmony with logical forms, on the basis of credo ut intelli/^am. Abelard opposed kim, on the principle that understanding should precede faith. This was the period of Nominalism and Realism, and also of the foundation of universities. Among the most prominent of the great names of this period is that of Eoscelinus of Compcigne, who is celebrated as having been tlie first to revive the question of the reality of universal ideas, and William of Cliampeaux, who open- ed a school of logic in I'aris in 1100. The fame of the latter was soon eclipsed by that of Peter Abelard, who was able to invest logical disputation with such fascina- tions as to make it the favorite occupation of the most intelligent minds for generations following.
Tlie 1.3th century is counted as the second period of scholasticism, during which the leading dialecticians ^vere Bonaventura, Albertus Magnus, Thomas Aquinas, and Duns Scotus. During this period scholasticism reached its climax. The 14th centur}-, as the third pe- riod of scholasticism, witnessed its sensible decline un- der the protracted but bitter wranglings of the Thomists (Realists) and Scotists (Nominalists).
Notwithstanding an attempt by the Medici of Flor- ence to revive the Platonic philosophy in opposition to that of Aristotle, the latter prevailed in the chief uni- versities of Europe, and the corruptions of it which had been countenanced by scholasticism began to pass away under the influence of more intelligent discussion. In the 16th century, after the invention of printing, the logical and philosophical works of the Stagirite were is- sued in a purer text and more accurate versions, and largely engaged public criticism.
The authority of Aristotle had been so long supreme in the continental universities, and the union between what passed for his philosophy and the errors of the Church of Rome had been so long established, that it was only natural for Luther and Melancthon, at the be- ginning of the Reformation, to inveigh strongly against the Aristotelian logic and metaphysics. As time passed on, however, it became apparent that the work of the Reformers had largely to be done through the agency of that same Aristotelian logic. Melancthon was not slow to perceive this, and subsequently became an ac- knowledged follower of Aristotle as to dialectics, and even influenced Luther to retract some of his severer ut- terances. He introduced into the University of Witten- berg, to which Protestant Germany looked up, a scheme of dialectics and physics founded upon the Aristotelian theory. He also imitated the Stagirite philosopher by teaching logic with constant reference to rhetoric. The advocacy and influence of Melancthon secured the pre- ponderance of the Aristotelian dialectics in the Protes- tant schools of (iermany for more than a centur}'.