The second difficulty which we noticed, that regarding the two forms in which Hume has left us his ethical theory, requires more immediate and altogether more serious attention. It will be remembered that his first treatment of Ethics appeared as Book III of the Treatise of Human Nature in 1740, the year after the publication of the other two books. The Inquiry concerning the Principles of Morals did not appear till 1751, three years after he had published the Inquiry concerning Human Understanding, in which he had presented, in a more popular form, the substance of Book I of the Treatise. The story of Hume's chagrin at the poor reception which his juvenile work met with, and of his explicit repudiation of the Treatise in after years, as not giving his mature views on philosophical subjects, is too familiar to admit of repetition. Critics are now perfectly agreed that the Inquiry concerning Human Understanding, however superior in style to the first book of the Treatise, is an inadequate statement of the author's views on metaphysics; and, since one is bound to disregard Hume's own judgment concerning the relative merits of Book I of the Treatise and the corresponding Inquiry, it is natural that the Inquiry concerning the Principles of Morals should have been estimated in much the same way, in spite of the fact that Hume himself considered the second Inquiry as "of all [his] writings, historical, philosophical or literary, incomparably the best." The present tendency plainly is either (1) to regard the two statements of his ethical theory as practically equivalent, and therefore to prefer Book III of the Treatise merely as historically prior; or (2) to hold that, in the Inquiry concerning the Principles of Morals, as well as in the Inquiry concerning Human Understanding, there is an observable falling off in thoroughness of treatment which is by no means compensated for by the undoubted improvement in style.
I cannot believe that either of these views is correct. It must never be forgotten that, in his later years, Hume was perfectly right in regarding the Treatise of Human Nature as a work abounding in serious defects, mainly such as betray the youth of the author. It is in spite of these defects that the
