It can be seen at once that the question of reason or sentiment as the basis for moral judgments is something more than an academic issue. The practical consequences which follow from these opposite points of view are of the greatest significance for estimating the values of human life. If moral judgments are derived from reason, they can be true or false. If they are based solely on the feelings, there can be no dispute concerning them. Truth is disputable but taste is not. Again, if moral judgments are true in the same sense that propositions in mathematics are true, they are not subject to change. The principles of morality would in that case be as eternal as the laws of mathematics. But if moral judgments are derived from the feelings, they do not remain constant. They will be as variable as the moods and sentiments of the individuals who make them.
The issue is a crucial one so far as the status of moral principles is concerned. Arguments have been stated in abundance in support of each of these opposing positions. Hume's own position is very definitely on the side of those who place the greater emphasis on feelings rather than reason as the basis for moral beliefs.
Several of Hume's contemporaries, as well as his predecessors, had given support to the rationalistic conception of ethics, and he was anxious to correct the errors which he saw in the views they had presented. His method for doing this was quite in harmony with the spirit of empiricism, which was being emphasized in the scientific inquiries of his day.
In contrast with the rationalists, who had derived their principles of morality by making deductions from metaphysical assumptions, Hume believed it was necessary to study the facts of human experience and to draw only those conclusions which are warranted by the facts. He regarded the attempt to base morality on one's conception of the nature of the universe a misguided one. Any knowledge that can be gained with reference to morals must come from a different source. He therefore proposes to begin the inquiry by examining the way in which moral ideas have been formed. Because the principles of benevolence and justice have been widely recognized as virtuous by people of all races and cultures, he begins with an investigation of the meanings that have been associated with these terms.
