Logic

Preface

In this edition of my Logic, the text has been revised throughout, several passages have been rewritten, and some sections added. The chief alterations and additions occur in cc. i., v., ix., xiii., xvi., xvii., xx.

The work may be considered, on the whole, as attached to the school of Mill; to whose System of Logic, and to Bain's Logic, it is deeply indebted. Amongst the works of living writers, the Empirical Logic of Dr. Venn and the Formal Logic of Dr. Keynes have given me most assistance. To some others acknowledgments have been made as occasion arose.

For the further study of contemporary opinion, accessible in English, one may turn to such works as Mr. Bradley's Principles of Logic, Dr. Bosanquet's Logic; or the Morphology of Knowledge, Prof. Hobhouse's Theory of Knowledge, Jevon's Principles of Science, and Sigwart's Logic. Ueberweg's Logic, and History of Logical Doctrine is invaluable for the history of our subject. The attitude toward Logic of the Pragmatists or Humanists may best be studied in Dr. Schiller's Formal Logic, and in Mr. Alfred Sidgwick's Process of Argument and recent Elementary Logic. The second part of this last work, on the "Risks of Reasoning," gives an admirably succinct account of their position. I agree with the Humanists that, in all argument, the important thing to attend to is the meaning, and that the most serious difficulties of reasoning occur in dealing with the matter reasoned about; but I find that a pure science of relation has a necessary place in the system of knowledge, and that the formulæ known as laws of contradiction, syllogism and causation are useful guides in the framing and testing of arguments and experiments concerning matters of fact. Incisive criticism of traditionary doctrines, with some remarkable reconstructions, may be read in Dr. Mercier's New Logic.

In preparing successive editions of this book, I have profited by the comments of my friends: Mr. Thomas Whittaker, Prof. Claude Thompson, Dr. Armitage Smith, Mr. Alfred Sidgwick, Dr. Schiller, Prof. Spearman, and Prof. Sully, have made important suggestions; and I might have profited more by them, if the frame of my book, or my principles, had been more elastic.

As to the present edition, useful criticisms have been received from Mr. S.C. Dutt, of Cotton College, Assam, and from Prof. M.A. Roy, of Midnapore; and, especially, I must heartily thank my colleague, Dr. Wolf, for communications that have left their impress upon nearly every chapter.

CARVETH READ.

LONDON, August, 1914

CHAPTER I

INTRODUCTORY

Section 1. Definition of Logic 1 Section 2. General character of proof 2 Section 3. Division of the subject 5 Section 4. Uses of Logic 6 Section 5. Relation of Logic to other sciences 8 to Mathematics (p. 8); to concrete Sciences (p. 10); to Metaphysics (p. 10); to regulative sciences (p. 11) Section 6. Schools of Logicians 11 Relation to Psychology (p. 13)

CHAPTER II

GENERAL ANALYSIS OF PROPOSITIONS

Section 1. Formal Consistency and Material Truth 159 Section 2. Real General Propositions assert more than has been directly observed 160 Section 3. Hence, formally, a Syllogism's Premises seem to beg the Conclusion 162 Section 4. Materially, a Syllogism turns upon the resemblance of the Minor to the Middle Term; and thus extends the Major Premise to new cases 163 Section 5. Restatement of the Dictum for material reasoning 165 Section 6. Uses of the Syllogism 167 Section 7. Analysis of the Uniformity of Nature, considered as the formal ground of all reasoning 169 Section 8. Grounds of our belief in Uniformity 173

CHAPTER XIV

CAUSATION

Section 1. The most important aspect of Uniformity in relation to Induction is Causation 174 Section 2. Definition of "Cause" explained: five marks of Causation 175 Section 3. How strictly the conception of Cause can be applied depends upon the subject under investigation 183 Section 4. Scientific conception of Effect. Plurality of Causes 185 Section 5. Some condition, but not the whole cause, may long precede the Effect; and some co-effect, but not the whole effect, may long survive the Cause 187 Section 6. Mechanical Causes and the homogeneous Intermixture of Effects; Chemical Causes and the heteropathic Intermixture of Effects 188 Section 7. Tendency, Resultant, Counteraction, Elimination, Resolution, Analysis, Reciprocity 189

CHAPTER XV

INDUCTIVE METHOD

Section 1. Outline of Inductive investigation 192 Section 2. Induction defined 196 Section 3. "Perfect Induction" 196 Section 4. Imperfect Induction methodical or immethodical 197 Section 5. Observation and Experiment, the material ground of Induction, compared 198 Section 6. The principle of Causation is the formal ground of Induction 201 Section 7. The Inductive Canons are derived from the principle of Causation, the more readily to detect it in facts observed 202

CHAPTER XVI

THE CANONS OF DIRECT INDUCTION

Section 1. Hypothesis defined and distinguished from Theory 266 Section 2. An Hypothesis must be verifiable 268 Section 3. Proof of Hypotheses 270 (1) Must an hypothetical agent be directly observable? (p. 270); Vera causa (p. 271) (2) An Hypothesis must be adequate to its pretensions (p. 272); Exceptio probat regulam (p. 274) (3) Every competing Hypothesis must be excluded (p. 275); Crucial instance (p. 277) (4) Hypotheses must agree with the laws of Nature (p. 279) Section 4. Hypotheses necessary in scientific investigation 280 Section 5. The Method of Abstractions 283 Method of Limits (p. 284); In what sense all knowledge is hypothetical (p. 286)

CHAPTER XIX

LAWS CLASSIFIED; EXPLANATION; CO-EXISTENCE; ANALOGY

Section 1. Meaning of Chance and Probability 310 Section 2. Probability as a fraction or proportion 312 Section 3. Probability depends upon experience and statistics 313 Section 4. It is a kind of Induction, and pre-supposes Causation 315 Section 5. Of Averages and the Law of Error 318 Section 6. Interpretation of probabilities 324 Personal Equation (p. 325); meaning of 'Expectation' (p. 325) Section 7. Rules of the combination of Probabilities 325 Detection of a hidden Cause (p. 326); oral tradition (p. 327); circumstantial and analogical evidence (p. 328)

CHAPTER XXI

DIVISION AND CLASSIFICATION

Section 1. The rigour of scientific method must be qualified 369 Section 2. Still, Language comprises the Nomenclature of an imperfect Classification, to which every Definition is relative; 370 Section 3. and an imperfect Terminology 374 Section 4. Maxims and precautions of Definition 375 Section 5. Words of common language in scientific use 378 Section 6. How Definitions affect the cogency of arguments 380