Appendix I
One of the most controversial issues in the history of ethical theory has to do with the respective place that should be given to reason and to the feelings in the formation of moral judgments. Throughout the Enquiry, Hume has recognized that both reason and the feelings are necessarily involved in the development of the principles of morality. It has not, however, been made entirely clear just what he believes the function of each of these two factors to be, and it is for the purpose of clarifying this point that he has added this appendix to the earlier work.
Because so much has been said in the various sections of the Enquiry concerning the feelings of approval for that which is useful and agreeable to ourselves and to others as the essential basis for morality, he now gives special attention to the subject of reason and the function which it performs in connection with moral sentiments. To make his position entirely clear, he finds it necessary to indicate both what it is that reason is capable of doing and what it is incapable of doing. This will not only throw light on the nature of the rational element that is involved in moral thinking, but it will enable one to avoid those errors which attribute to reason a function which properly belongs to the feelings.
In the first place, it requires no argument at all to establish the fact that reason is an indispensable tool for finding out what actions are the ones most likely to be of the greatest use in meetings the needs of a human society. This information will need to be based on past experiences, and obviously reason, or correct thinking, will be involved in drawing inferences with reference to the meaning of these past events and the likelihood of similar occurrences taking place in the future.
Calculations of this kind are not always an easy or simple process. Complications arise because what is of immediate benefit to one person or one group of persons may be detrimental to their interests in the future. Again, it is not at all uncommon for situations to develop where benefits to one group are at the same time decidedly injurious to others. Furthermore, because conditions are constantly changing, what was beneficial under one set of circumstances may be detrimental under the changed conditions. Reason must take into account all of these factors and determine with as much accuracy as is possible those actions which under the new and emerging conditions will be most useful in meeting human needs.
