Peter Kreeft - Socratic Logic: : A Logic Text using Socratic Method, Platonic Questions, and Aristotelian Principles, Edition 3.1

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A LOGIC TEXT USINGSOCRATIC METHOD,PLATONIC QUESTIONS, &ARISTOTELIAN PRINCIPLES

Modeling Socratcs as the ideal teacher for the beginnerand Socratic method as the ideal methodIntroducing philosophical issues along with logicby being philosophical about logic and logical about philosophy

Presenting a complete system of classical Aristotelian logic,the logic of ordinary language and of the four language arts,reading, writing, listening, and speaking

ST AUGUSTINE'S PRESS Copyright 2004, 2005, 2008, 2010, 2014 by Peter Kreeft

All rights reserved. No part of this book may be reproduced,stored in a retrieval system, or transmitted, in any form or by anymeans, electronic, mechanical, photocopying, recording, or otherwise,without the prior permission of St. Augustine's Press.

Manufactured in the United States of America345620191817161514

Library of Congress Cataloging in Publication DataKreeft, Peter.
Socratic logic:
a logic text using Socratic method, Platonic questions & Aristotelianprinciples / by Peter Kreeft; edited by Trent Dougherty. - Ed. 3.1.p. cm.
Previously published: 3rd ed. c2008.
Includes bibliographical references and index.ISBN 978-1-58731-808-5 (hardcover: alk. paper)1. Logic.I. Dougherty, Trent. II. Title.
BC108.K67 2010
160 - dc222010032937

ooThe paper used in this publication meets the minimum requirementsof the American National Standard for Information Sciences - Permanenceof Paper for Printed Materials, ANSI Z39.48-1984.

ST. AUGUSTINE'S PRESS www.staugustine.net PREFACEix PREFACEix

2. Concepts, terms and words (P)40

2. Fallacies of diversion80
3. Fallacies of oversimplification86
4. Fallacies of argumentation92

"P" = "philosophical"; "B" = "basic." See p.13, last paragraph. VI SOCRATI C LOGI C

5. Inductivc fallacies100
6. Procedural fallacies104
7. Metaphysical fallacies109
8. Short Story: "Love Is a Fallacy"114

IV. DEFINITION123
1. The nature of definition (B)123
2. The rules of definition (B)124
3. The kinds of definition124
4. The limits of definition129

V. THE SECOND ACT OF THE MIND: JUDGMENT138
1. Judgments, propositions, and sentences138
2. What is truth? (P)143
3. The four kinds of categorical propositions (B)145
4. Logical form (B)147
5. Euler's circles (B)152
6. Tricky propositions153
7. The distribution of terms163

VI. CHANGING PROPOSITIONS166
1. Immediate inference166
2. Conversion (B)167
3. Obversion (B)170
4. Contraposition171

VII. CONTRADICTION173
1. What is contradiction? (B)173
2. The Square of Opposition (B)174
3. Existential import (P)179
4. Tricky propositions on the Square181
5. Some practical uses of the Square of Opposition183

VIII. THE THIRD ACT OF THE MIND: REASONING186
1. What does "reason" mean? (P)186
2. The ultimate foundations of the syllogism (P)187
3. How to detect arguments190
4. Arguments vs. explanations193
5. Truth and validity194

Contents vii

IX. DIFFERENT KINDS OF ARGUMENTS200
1. Three meanings of "because"200
2. The four causes (P)202
3. A classification of arguments205
4. Simple argument maps (B)206
5. Deductive and inductive reasoning (B)210
6. Combining induction and deduction: Socratic method (P)211

X. SYLLOGISM S215
1. The structure and strategy of the syllogism (B)215
2. The skeptic's objection to the syllogism (P)219
3. The empiricist's objection to the syllogism (P)222
4. Demonstrative syllogisms230
5. How to construct convincing syllogisms (B)232

XI. CHECKING SYLLOGISMS FOR VALIDITY237
1. By Euler's Circles (B)237
2. By Aristotle's six rules (B)242
3. "Barbara Celarent": mood and figure257
4. Venn Diagrams258

XII. MORE DIFFICULT SYLLOGISMS264
1. Enthymemes: abbreviated syllogisms (B)264
2. Sorites: chain syllogisms275
3. Epicheiremas: multiple syllogisms (B)279
4. Complex argument maps282

XIII. COMPOUN D SYLLOGISMS2891. Hypothetical syllogisms (B)2892."Reductio ad absurdum " arguments294

3. The practical syllogism: arguing about means and ends296
4. Disjunctive syllogisms (B)301
5. Conjunctive syllogisms (B)303
6. Dilemmas (B)306

XIV. INDUCTION313
1. What is induction?313
2. Generalization315
3. Causal arguments: Mill's methods319

viii SOCRATI C LOG1 C

4. Scientific hypotheses325
5. Statistical probability328
6. Arguments by analogy329
7. A fortiori and a minore arguments335

XV. SOME PRACTICAL APPLICATIONS OF LOGIC342
1. How to write a logical essay342
2. How to write a Socratic dialogue344
3. How to have a Socratic debate348
4. How to use Socratic method on difficult people350
5. How to read a book Somatically355

XVI. SOME PHILOSOPHICAL APPLICATIONS OF LOGIC358
1. Logic and theology (P)358
2. Logic and metaphysics (P)359
3. Logic and cosmology (P)360
4. Logic and philosophical anthropology (P)361
5. Logic and epistemology (P)362
6. Logic and ethics (P)362

APPENDIX: PROBLEMS WITH MATHEMATICAL LOGIC364
1. Basic modern logic364
2. The paradoxes of material implication366
3. Responses to the paradoxes of material implication367

ANSWERS TO EVEN-NUMBERED EXERCISES370INDEX OF PRINCIPAL NAMES400 This book is a dinosaur.

Once upon a time in Middle-Earth, two things were different: (1) most students learned "the old logic," and (2) they could think, read, write, organize, andargue much better than they can today. If you believe these two things are notconnected, you probably believe storks bring babies.

It is time to turn back the clock. Contrary to the cliche, you can turn backthe clock, and you should, whenever it is keeping bad time. (I learned that, andthousands of other very logical paradoxes, from G.K. Chesterton, the 20th-century Socrates.)

As I write this, it is the last Sunday of October, and we have just turned backour clocks from daylight savings time to standard time. This is a parable for whatI am convinced we must do in logic. The prevailing symbolic/mathematical logicis a logic that a computer can do; it is artificial, like daylight savings time. It isvery useful where there is already much intelligence (in the minds of geniuses,especially in science),just as daylight savings time is very useful in the summerwhen there is a plenitude of sunlight. But as the sunlight of clear thinking, writing, reading, and debating decreases in our society, it is time to make progressby turning back the clock from "daylight savings time" to real time, real language, real people, and the real world. The old Socratic-Platonic-Aristotelianlogic is simply more effective than the new symbolic logic in helping ordinarypeople in dealing with those four precious things.

This text differs from nearly all other logic texts in print in the three wayssuggested by the subtitle. It does this by apprenticing itself to the first three greatphilosophers in history, Socrates, Plato, and Aristotle. (Do we have better onestoday?)

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