Lf?£ THE TEACH YOURSELF BOOKS LOGIC Uniform with this volume and in the same series Teach Yourself: Analytical Psychology Teach Yourself Anthropology Teach Yourself Astronomy Teach Yourself: The Christian Faith Teach Yourself Christian Theology Teach Yourself Ethics The Teach Yourself Guidebook to Western Thought Teach Yourself: History of Philosophy Teach Yourself: History of Religions Teach Yourself Philosophy Teach Yourself: Philosophy of Religion Teach Yourself Political Thought Teach Yourself: Preaching Teach Yourself Psychology Teach Yourself: Roman Catholicism Teach Yourself to Study Teach Yourself to Think Teach Yourself: Zen—A Way of Life TEACH YOURSELF LOGIC By A. A. LUCE M.C., D.D., Litt.D. Trinity College, Dublin THE ENGLISH UNIVERSITIES PRESS LTD st. Paul’s house Warwick lane LONDON EC4 First printed 19j8 This impression 1966 © Copyright The English Universities Press Ltd 1958 Printed in Great Britain for the English Universities Press Ltd by Butler & Tanner Ltd., Frome and London PREFACE Logic can be taught in various ways, and a teacher soon finds by experience the method that best suits his own style. The following hints are for those who are teaching themselves from this textbook. The book follows the natural articulations of the subject-matter, and it can be read through solidly from beginning to end. For be¬ ginners, however, I recommend the selective reading, indicated below, which concentrates first on the outline structure or skeleton of syllogistic Logic, before going on to the complete, continuous reading. This plan of reading keeps the structure of Logic steadily before the learner’s eye; the details are seen in perspective, and the skeleton is gradually clothed with flesh and blood. The plan would work out as follows : Glance through the first chapter and get the general notion. From Chapters II, III, IV, and V select pages 12-18, 34-55, and 64-95 for slow, patient, and thorough study. Do exercises as you go along, your own or from those printed at the end of the chapter. Understand as you read, and do not read far ahead of what you have under¬ stood. From these selections you will learn enough about terms to understand the structure of the proposition, and enough about propositions to grasp the structure of the syllogism, and enough about syllogisms to be able to prove the Special Rules of the Figures. When you can prove those rules with ease, you have grasped the outline structure and skeleton of syllogistic Logic. That done, go back to Chapter I and read the whole book continuously. The gaps will now close. The sections VI PREFACE on the technical classifications of terms, and non-categorical propositions, etc., omitted at the first reading, will now come easily to you, and you can pass on to the study of the Moods and Reduction, and thence to the more miscel¬ laneous contents of Chapters VII and VIII. Chapters IX and X point on to more advanced studies and should be left for the last. May reminiscence be permitted here and a piece of personal experience ? I taught myself Logic in my youth from a small old-fashioned manual. It was not written for logicians, but for the non-specialized pass-man, and without unnecessary technicalities or trimmings it set out the basic and timeless truths of traditional Logic, some knowledge of which is essential, in my opinion, to a consciously correct and rational use of our mother-tongue. I found the subject difficult at first; it was not like any of my school subjects ; but when I had crossed the thres¬ hold, an inner door swung open. I took a step forward in self-knowledge, and thought and speech became self- conscious. Like Moliere’s M. Jourdain who found that he had long been speaking prose, I found that I had long been forming propositions. I said to myself, “ Yes, I form propositions when my tongue does more than wag. I form them out of terms. I say something about some¬ thing. Therefore I ought to be able, in serious talk, to pin-point those two parts of my proposition. I ought to know exactly what I am talking about, and exactly what I am saying about it.” Soon inference, too, became self- conscious. From a child I had inferred and reasoned; now I began to do so wittingly, aware of the traps and the pitfalls, and aware of a norm and an ideal. In lecturing on Logic to University men and women, over and over again I have seen the same door swing open,