An Introduction To Logic And Scientific Method

An Introduction to LOGIC and SCIENTIFIC METHOD BY MORRIS R. COHEN Department of Philosophy, College of the City of New York AND ERNEST NAGEL Department of Philosophy, Columbia University HARCOURT, BRACE WORLD, INC. NEW YORK AND BURLINGAME COPYRIGHT, 1934, BY EARCOTJRT, BRACE WORLD, INC, All rights reserved, including the right to reproduce this book or portions thereof in any form. PRINTED IN THE UNITED STATES OF AMERICA PREFACE Though formal logic has in recent times been the object of radi cal and spirited attacks from many and diverse quarters, it con tinues, and will probably long continue, to be one of the most fre quently given courses in colleges and universities here and abroad. Nor need this be surprising when we reflect that the most serious of the charges against formal logic, those against the syllogism, are as old as Aristotle, who seems to have been fully aware of them. But while the realm of logic seems perfectly safe against the attacks from without, there is a good deal of unhappy confusion within. Though the content of almost all logic books follows even in many of the illustrations the standard set by Aristotles Organon terms, propositions, syllogisms and allied forms of inference, scientific method, probability and fallacies there is a bewildering Babel of tongues as to what logic is about. The different schools, the tradi tional, the linguistic, the psychological, the epistemological, and the mathematical, speak different languages, and each regards the other as not really dealing with logic at all. No task is perhaps so thankless, or invites so much abuse from all quarters, as that of the mediator between hostile points of view. Nor is the traditional distrust ofthe peacemaker in the intellectual realm difficult to appreciate, since he so often substitutes an unclear and inconsistent amalgam for points of view which at least have the merit of a certain clarity. And yet no task is so essential, especially for the beginner, when it is undertaken with the objective of ad justing and supplementing the claims of the contending parties, and when it is accompanied by a refusal to sacrifice clarity and rigor in thought. In so far as an elementary text permits such a thing, the present text seeks to bring some order into the confusion of tongues con cerning the subject matter of logic. But the resolution of the con flicts between various schools which it effects appears in the selec tion and presentation of material, and not in extensive polemics against any school. The book has been written with the conviction Iv PREFACE that logic is the autonomous science o the objective though formal conditions of valid inference. At the same time, its authors believe that the aridity which is not always unjustly attributed to the study of logic testifies to the unimaginative way logical principles have been taught and misused. The present text aims to combine sound logical doctrine with sound pedagogy, and to provide illus trative material suggestive of the role of logic in every department of thought. A text that would find a place for the realistic formalism of Aristotle, the scientific penetration of Peirce, the pedagogical soundness of Dewey, and the mathematical rigor of Russell this was the ideal constantly present to the authors of this book. However inadequately this ideal is embodied in the present text, the embodiment is not devoid of positive doctrine, so presented that at least partial justice is done to supplementary approaches to logic. 1. The traditional view of logic as the science of valid inference has been consistently maintained, against all attempts to confuse logic with psychology, where by the latter is meant the systematic study of how the mind works. Logic, as the science of the weight of evidence in all fields, cannot be identified with the special science of psychology. For such a special science can establish its results only by using criteria of validity employed in other fields as well...