The influence which Hume's philosophy exercised over that of Adam Smith has already been noticed with respect to the fundamental facts of sympathy, and the part played by them in the formation of our moral sentiments. But it is chiefly with respect to the position of Utility in moral philosophy that Adam Smith's theory is affected by Hume's celebrated Inquiry concerning, the Principles of Morals . Not only are all his speculations coloured by considerations of utility, but be devotes a special division of his book to the "Effect of Utility upon the Sentiment of Approbation."In Adam Smith's theory, the tendency of any affection to produce beneficial or hurtful results is only one part of the phenomenon of moral approbation, constituting our sense of merit or demerit, while the other part consists in our perception of the propriety or impropriety of the affection to the object which excites it. And as the sense of the merit or demerit of any action or conduct is much stronger than our sense of the propriety or impropriety of affections; stimulating us, not merely to a passive feeling of approbation or the contrary, but to a desire to confer actual reward or punishment on the agent, it is evident that the greater part of moral approbation consists in the perception of utility of tendency.
So far, Adam Smith agrees with the utilitarian theory but he refuses altogether to assent to the doctrine, that the perception of the utility of virtue is its primary recommendation, or that a sense of the evil results of vice is the origin of our hatred against it. It is true that the tendency of virtue to promote, and of vice to disturb the order of society, is to reflect a very great beauty on the one, and a very great deformity on the other. But both the beauty and the deformity are additional to an already existent beauty and deformity, and a beauty and deformity inherent in the objects themselves. Human society may be compared to "an immense machine, whose regular and harmonious movements produce a thousand agreeable effects.
As in any other beautiful and noble machine that was the production of human art, whatever tended to render its movements more smooth and easy, would derive a beauty from this effect; and on the contrary, whatever tended to obstruct them, would displease upon that account; so virtue, which is, as it were, the fine polish to the wheels of society, necessarily pleases;while vice, like the vile rust, which makes them jar and grate upon one another, is as necessarily offensive."According to Hume, the whole approbation of virtue may be resolved into the perception of beauty which results from the appearance of its utility, no qualities of the mind being ever approved of as virtuous, or disapproved of as vicious, but such as are either useful or agreeable to the person himself, or to others, or else have a contrary tendency. Adam Smith fully admits the fact, that the characters of men may be fitted either to promote or to disturb the happiness both of the individual himself and of the society to which he belongs, and that there is a certain analogy between our approbation of a useful machine and a useful course of conduct. The character of prudence, equity, activity, and resolution, holds out the prospect of prosperity and satisfaction both to the person himself and to every one connected with him; whilst the rash, insolent, slothful, or effeminate character, portends ruin to the individual, and misfortune to all who have anything to do with him. In the former character there is all the beauty which can belong to the most perfect machine ever invented for promoting the most agreeable purpose; in the other there is all the deformity of an awkward and clumsy contrivance.
But this perception of beauty in virtue, or of deformity in vice, though it enhances and enlivens our feelings with regard to both, is not the first or principal source of our approbation of the one, or of our dislike for the other.
"For, in the first place, it seems impossible that the approbation of virtue should be a sentiment of the same kind with that by which we approve of a convenient and well-contrived building; or, that we should have no other reason for praising a man than that for which we commend a chest of drawers.""And, secondly, it will be found, upon examination, that the usefulness of any disposition of mind is seldom the first ground of our approbation;and that the sentiment of approbation always involves in it a sense of propriety quite distinct from the perception of utility."For instance, superior reason and understanding is a quality most useful to ourselves, as enabling us to discern the remote consequences of our actions, and to foresee the advantage or disadvantage likely to result from them; but it is a quality originally approved of as just and right, and accurate, and not merely as useful or advantageous. Self-command, also, is a virtue we quite as much approve of under the aspect of propriety, as under that of utility. It is the correspondence of the agent's sentiments with our own, that is the source of our approbation of them; and it is only because his pleasure a week or a year hence is just as interesting or indifferent to us, as spectators, as the pleasure that tempts him at this moment, that we approve of his sacrifice of present to future enjoyment.
We approve of his acting as if the remote object interested him as much as the future one, because then his affections correspond exactly with our own, and we recognize the perfect propriety of his conduct..