In preparing this work for the second edition, I have found it desirable to make numerous alterations and additions. Indeed the extent which these have reached is so considerable, that I have thought it well to publish them in a separate form, for the use of purchasers of my first edition. On one or two points I have to acknowledge a certain change of view; which is partly at least due to criticism. For instance, in chap. iv. of Book i. (on “Pleasure and Desire”), which has been a good deal criticised by Prof. Bain and others, although I still retain my former opinion on the psychological question at issue, I have been led to take a different view of the relation of this question to Ethics; and in fact § 1 of this chapter as it at present stands directly contradicts the corresponding passage in the former edition. So again, as regards the following chapter, on ‘Free-Will,’ though I have not exactly found that the comments which it has called forth have removed my difficulties in dealing with this time-honoured problem, I have become convinced that I ought not to have crudely obtruded these difficulties on the reader, while professedly excluding the consideration of them from my subject. In the present edition therefore I have carefully limited myself to explaining and justifying the view that I take of the practical aspect of the question. I have further been led, through study of the Theory of Evolution in its application to practice, to attach somewhat more importance to this theory than I had previously done; and also in several passages of Books iii. and iv. to substitute ‘well-being’ for ‘happiness,’ in my exposition of that implicit reference to some further end and standard which reflection on the Morality of Common Sense continually brings into view. This latter change however (as I explain in the concluding chapter of Book iii.) is not ultimately found to have any practical effect. I have also modified my view of ‘objective rightness,’ as the reader will see by comparing Book i. chap. i. § 3 with the corresponding passage in the former edition; but here again the alteration has no material importance. In my exposition of the Utilitarian principle (Book iv. chap. i.) I have shortened the cumbrous phrase ‘greatest happiness of the greatest number’ by omitting--as its author ultimately advised--the last four words. And finally, I have yielded as far as I could to the objections that have been strongly urged against the concluding chapter of the treatise. The main discussion therein contained still seems to me indispensable to the completeness of the work; but I have endeavoured to give the chapter a new aspect by altering its commencement, and omitting most of the concluding paragraph.