In this theory also Adam Smith recognizes some elements of truth. "That virtue consists in conformity to reason is true in some respects; and this faculty may very justly be considered as, in some sense, the source and principle of moral approbation and disapprobation, and of all solid judgments concerning right and wrong." Induction too is one of the operations of reason, and it is by induction and experience that the general rules of morality are formed. They are established inductively, from the observation in a number of particular cases of what is pleasing or displeasing to our moral faculties. So it is by reason that we discover those general rules of justice by which we ought to regulate our actions; and by the same faculty we form those more indeterminate ideas of what is prudent, decent, generous, or noble, according to which we endeavour to model our conduct. And as it is by these general rules, so formed by an induction of reason, that we most regulate our moral judgments, which would be very variable if they depended merely upon feeling and sentiment, virtue may so far be said to consist in conformity to reason, and so far may reason be considered as the source of moral approbation.
This admission, however, is a very different thing from the supposition that our first perceptions of right and wrong can be derived from reason.
These first perceptions, upon which from a number of particular cases the general rules of morality are founded, must be the object of an immediate souse and feeling, not of reason. "It is by finding in a vast variety of instances that one tenor of conduct constantly pleases in a certain manner, and that another as constantly displeases the mind, that we form the general rules of morality. But reason cannot render any particular object either agreeable or disagreeable to the mind for its own sake. Reason may show that this object is the means of obtaining some other which is naturally either pleasing or displeasing, and in this manner may render it either agreeable or disagreeable for the sake of something else; but nothing can be agreeable or disagreeable for its own sake, which is not rendered such by immediate sense and feeling. If virtue, therefore, in every particular instance, necessarily pleases for its own sake, and if vice as certainly displeases the mind, it cannot be reason, but immediate sense and feeling which in this manner reconciles us to the one and alienates us from the other."There remained therefore the theories which made sentiment or feeling the original source of moral approbation; and the best exposition of this theory was that given by Hutcheson in his doctrine of the Moral Sense.
If the principle of approbation was founded neither on self- love nor on reason, there must be some faculty of a peculiar kind, with which the human mind was endowed to produce the effect in question. Such a faculty was the moral sensea particular power of perception exerted by the mind at the view of certain actions and affections, by which those that affected the mind agreeably were immediately stamped with the characters of right, laudable, and virtuous, while those that affected it otherwise were immediately stamped with the characters of wrong, blameable, and vicious.
This moral sense was somewhat analagous to our external senses; for as external bodies, by affecting our senses in a certain way, seemed to possess the different qualities of sound, taste, smell, or colour, so the various affections of the mind, by touching the moral sense in a certain way, appeared to possess the different qualities of right or wrong, of virtue or of vice. The moral sense too was a reflex internal sense, as distinct from a direct internal sense; that is to say, as the perception of beauty was a reflex sense presupposing the direct sense which perceived objects and colours, so the perception of the beauty or deformity of passions and affections was a reflex sense presupposing the perception by a direct internal sense of the several passions and affections themselves. Other reflex senses of the same kind were, a public sense, by which we sympathize with the happiness or misery of our fellows; a sense of shame and honour;and a sense of ridicule.
One consequence of this analogy between the moral sense and the external senses, and a consequence drawn by Hutcheson himself, was that our moral faculties themselves could not be called virtuous or vicious, morally good or morally evil; for the qualities of any object of sense cannot be applied to the sense itself. An object may have the quality of black or white, but the sense of seeing is not black nor white; and in the same way, though an action or sentiment may appear good or bad, the qualities of goodness or badness cannot attach to the moral faculty which perceives such qualities in nature.