Logic, inductive and deductive; an introduction to scientific method

Preface

This book is intended as a text-book and not at all as a contribution to logical theory. It aims to present an outline of scientific method as briefly and as concretely as possible. It is not designed to serve as an introduction to general philosophy. Its chief claim to novelty is in the arrangement of the subject matter. The traditional arrangement in which the deductive processes are presented first usually leaves with the student the impression that method is chiefly deduction, and that there is no very close connection between this and the rest of subject. The arrangement, which is here adopted, was selected on pedagogical grounds and not in the interests of any epistemological theory.

The justification for dogmatic statements on disputed points is also pedagogical. Argument on such points in a text-book usually fails to interest the student and often tends to make him think that the whole subject is in an uncertain state and mostly a matter of opinion. Some subjects are treated much more briefly than they deserve, but I wished to keep them in due proportion with the rest.

Fallacies are first discussed along with the processes with which they are connected, but they are all brought together in a later chapter. Many of the exercises are new, but I have also drawn freely from other text-books. The longer exercises at the end of the book give the student an opportunity to bring to bear alvi PREFACE

most the whole of scientific method, and for this reason they seem to me to be very important.

My indebtedness to Jevons, Hyslop, Mill, and Bowley will be obvious. I owe much to Aikins' Principles of Logic; his broader treatment of many topics and his chapters on Testimony, Averages, Statistics, etc., were very suggestive. Sidgwick's The Use of Words in Reasoning, Creighton's treatment of the Figures of the Syllogism in his Introduction to Logic, Hibben's use of the idea of system in his Logic and Cramer's The Method of Darwin, were also suggestive. I have tried to give credit in each case in which I am conscious of having borrowed.

I am much indebted to three of my former colleagues in Princeton University: to Professor W. T. Marvin for going over the whole of the copy and giving me much useful advice, and to Professors W. H. Sheldon and E. M. Rankin for assistance with the proof; and to my colleagues, Professors Woodbridge and Montague, for many valuable discussions of logical problems.

A. L. J.

New York, April, 1909.

PAGE

Part I An Outline Of Scientific Method

Science and Common Sense — Induction and Deduction included in Scientific Method — The Beginning of knowledge — Natural Sciences and others — The Sources of Knowledge, Direct and Indirect — Organizing knowledge — Classification as a preliminary step — Language as a necessary instrument — Further steps in organized knowledge — ^What is presupposed? 1

Kinds of Propositions — Propositions and Terms — The Relation of Subject and Predicate — The Distribution of Terms in a proposition — Euler's Method — Ambiguous Propositions o . . . o 66

Chapter VI

Generalization and what it includes — Causal Connection — Testing Inductive inferences — Complete Enumeration — How Generalizations are verified — Observation and Analysis are pre-supposed — Postponing inference till test conditions are present — The Inductive Methods. . . 79

TRADITIONAL TREATMENT OF THE

SYLLOGISM

Traditional treatment — Moods — Figures — Note on the Reduction of the Moods and Figures 137

Chapter X

ABBREVIATED AND COMPLEX FORMS OF REASON- ING—HYPOTHETICAL AND DISJUNCTIVE

SYLLOGISMS

The Enthymeme — Prosyllogisnl and Episyllogism — The Sorites — Hypothetical Reasoning — Disjunctive Reasoning — More Complex Forms — Extra-syllogistic Reasoning . 151

CONTENTS ix

Chapter XI pagq

I. PROOF AND DISPROOF 11. FAILURE TO PROVE Various Kinds of Proof — Failures to Prove — Fallacies . < 166 General Exercises • . • • . 177

PART II SUPPLEMENTARY METHODS Statistics, their uses and limits — Correlation — The Processes

used in Statistical Investigations 189

Chapter II

The Arithmetical Average — The " Weighted " Average — The Mode — The Median — The Geometrical Average — Measuring Deviations from an average — Measurement of phenomena — The Comparison of quantities which cannot be measured , 198

Chapter III

The Meaning of Probability — Deducing the probability of a phenomenon — Dangers to be avoided in interpreting probability 213

Supplement to Part II

The Graphic Method of Representing Data and Their Relations 326

Part III The Construction Of Systems

EXPLANATION

What is Explanation? 237

X CONTENTS

FAGB

Chapter II

What is an Hypothesis? — The Value of Hypotheses — H6w are Hypotheses suggested to us? — Requisites of a good hypothesis 246

Chapter III

The Geometric System — Others closely related to this — Systems which are more concerned with concrete phenomena — Systems of Historical Facts 257

Exercises in^ the examination of complex reasoning

Professor James's Argument for his Theory of the*Emotions —A. H. Fison on "The Evolution of Double Stars"— Huxley on " The Demonstrative Evidence of Evolution " 279