The relations of this work to works preceding it in the series are such as to involve frequent reference. Containing, as it does, the outcome of principles set forth in each of them, I have found it impracticable to dispense with re-statements of those principles. Further, the presentation of them in their relations to different ethical theories, has made it needful, in every case, briefly to remind the reader what they are, and how they are derived. Hence an amount of repetition which to some will probably appear tedious. I do not, however, much regret this almost unavoidable result; for only by varied iteration can alien conceptions be forced on reluctant minds. _June_, 1879. CONTENTS. CHAPTER I. PAGE. Conduct in General 1 CHAPTER II. The Evolution of Conduct 7 CHAPTER III. Good and Bad Conduct 23 CHAPTER IV. Ways of Judging Conduct 54 CHAPTER V. The Physical View 75 CHAPTER VI. The Biological View 88 CHAPTER VII. The Psychological View 121 CHAPTER VIII. The Sociological View 157 CHAPTER IX. Criticisms and Explanations 178 CHAPTER X. The Relativity of Pains and Pleasures 206 CHAPTER XI. Egoism versus Altruism 221 CHAPTER XII. Altruism versus Egoism 237 CHAPTER XIII. Trial and Compromise 258 CHAPTER XIV. Conciliation 285 CHAPTER XV. Absolute and Relative Ethics 304 CHAPTER XVI. The Scope of Ethics 332 THE DATA OF ETHICS. CHAPTER I. CONDUCT IN GENERAL. § 1. The doctrine that correlatives imply one another--that a father cannot be thought of without thinking of a child, and that there can be no consciousness of superior without a consciousness of inferior--has for one of its common examples the necessary connection between the conceptions of whole and part. Beyond the primary truth that no idea of a whole can be framed without a nascent idea of parts constituting it, and that no idea of a part can be framed without a nascent idea of some whole to which it belongs, there is the secondary truth that there can be no correct idea of a part without a correct idea of the correlative whole. There are several ways in which inadequate knowledge of the one involves inadequate knowledge of the other.