Studies and Exercises in Formal Logic — John Neville Keynes
Studies and Exercises in Formal Logic | Project Gutenberg You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org . If you are not located in the United States, you will have to check the laws of the country where you are located before using this eBook. Title : Studies and Exercises in Formal Logic Author : John Neville Keynes Release date : May 24, 2019 [eBook #59590] Most recently updated: September 6, 2023 Language : English Other information and formats : www.gutenberg.org/ebooks/59590 Credits : Ed Brandon from material at the Internet Archive *** START OF A., Sc.D. UNIVERSITY LECTURER IN MORAL SCIENCE AND FORMERLY FELLOW OF PEMBROKE COLLEGE IN THE UNIVERSITY OF CAMBRIDGE FOURTH EDITION RE-WRITTEN AND ENLARGED 𝕷𝖔𝖓𝖉𝖔𝖓 MACMILLAN AND CO., LIMITED NEW YORK: THE MACMILLAN COMPANY 1906 [ The Right of Translation and Reproduction is reserved ] First Edition ( Crown 8 vo. ) printed 1884. Second Edition ( Crown 8 vo. ) 1887. Third Edition ( Demy 8 vo. ) 1894. Fourth Edition ( Demy 8 vo. ) 1906. PREFACE TO THE FOURTH EDITION. I N this edition many of the sections have been re-written and a good deal of new matter has been introduced. The following are some of the more important modifications. In Part I a new definition of “connotative name” is proposed, in the hope that some misunderstanding may thereby be avoided; and the treatment of negative names has been revised. In Part II the problem of the import of judgments and propositions in its various aspects is dealt with in much more detail than before, and greater importance is attached to distinctions of modality. Partly in consequence of this, the treatment of conditional and hypothetical propositions has been modified. I have partially re-written the chapter on the existential import of propositions in order to meet some recent criticisms and to explain my position more clearly. Many other minor changes in Part II have been made. Amongst the changes in Part III are a more systematic treatment of the process of the indirect reduction of syllogisms, and the introduction of a chapter on the characteristics of inference. An appendix on the fundamental laws of thought has been added; and the treatment of complex propositions which previously constituted Part IV of the book has now been placed in an appendix. The reader of this edition will perceive my indebtedness to Sigwart’s Logic . I have received valuable help from Professor J. S. Mackenzie and from my son, Mr J. M. Keynes; and I cannot express too strongly the debt I once more owe to Mr W. E. Johnson, who by his criticisms has enabled me to improve my exposition in many parts of the book, and also to avoid some errors. J. N. KEYNES. 6, H ARVEY R OAD , C AMBRIDGE , 4 September 1906. vi PREFACE TO THE FIRST EDITION. 1 1 With some omissions. I N addition to a somewhat detailed exposition of certain portions of what may be called the book-work of formal logic, the following pages contain a number of problems worked out in detail and unsolved problems, by means of which the student may test his command over logical processes. In the expository portions of Parts I, II, and III, dealing respectively with terms, propositions, and syllogisms, the traditional lines are in the main followed, though with certain modifications; e.g. , in the systematisation of immediate inferences, and in several points of detail in connexion with the syllogism. For purposes of illustration Euler’s diagrams are employed to a greater extent than is usual in English manuals. In Part IV, which contains a generalisation of logical processes in their application to complex inferences, a somewhat new departure is taken. So far as I am aware this part constitutes the first systematic attempt that has been made to deal with formal reasonings of the most complicated character without the aid of mathematical or other symbols of operation, and without abandoning the ordinary non-equational or predicative form of proposition. This attempt has on the whole met with greater success than I had anticipated; and I believe that the methods formulated will be found to be both as easy and as effective as the symbolical methods of Boole and his followers. The book concludes with a general and sure method of solution of what Professor Jevons called the inverse problem, and which he himself seemed to regard as soluble only by a series of guesses. The writers on logic to whom I have been chiefly indebted are De Morgan, Jevons, and Venn. To Mr Venn I am peculiarly indebted, not merely by reason of his published writings, vii especially his Symbolic Logic , but also for most valuable suggestions and criticisms while this book was in progress. I am glad to have this opportunity of expressing to him my thanks for the ungrudging help he has afforded me. I am also under great obligation to Miss Martin of Newnham College, and to Mr Caldecott of St John’s College, for criticisms which I have found extremely helpful. C AMBRIDGE , 19 January 1884. viii PREFACE TO THE SECOND EDITION. T HIS edition has been carefully revised, and numerous sections have been almost entirely re-written. In addition to the introduction of some brief prefatory sections, the following are among the more important modifications. In Part I an attempt has been made to differentiate the meanings of the three terms connotation, intension, comprehension, with the hope that such differentiation of meaning may help to remove an ambiguity which is the source of much of the current controversy on the subject of connotation. In Part II a distinction between conditional and hypothetical propositions is adopted for which I am indebted to Mr W. E. Johnson; and the treatment of the existential import of propositions has been both expanded and systematised. In Part IV particular propositions, which in the first edition were practically neglected, are treated in detail; and, while the number of mere ex