Much has been made of the notion that there are foundational differences between David Hume and Thomas Reid's accounts of morality, with Hume allegedly emphasizing moral sentiments and Reid emphasizing the role of reason. However, despite Hume's early relegation of reason to the role of being merely a servant of the passions in his Treatise (T), later in the opening paragraphs of his Enquiry Concerning the Principles of Morals (EPM) he makes a strident attack on moral skeptics who, he says, shun common sense and reason.

Adam Smith offers a third account, one that aligns well in part with both Hume and Reid. This chapter will discuss these accounts in relation to one another. Its conclusion is that, although significant differences among the three can, indeed, be found, all of them contend their views are grounded in empirically observable features of our human constitution, including both reason and sentiment.

However, observable these features may be, accounts of their contributions to morality require carefully attending to how they develop in childhood. Fortunately, Reid's Essays on the Active Powers of Man (AP) and Smith's Theory of the Moral Sentiments (TMS) attempt this. Unfortunately, Hume's writings do not. Still, all three philosophers give us reason to conclude that children, not just adults, are capable of significant critical thinking about moral issues, and that it is important that this be encouraged.

Hume's Treatise (T) and Enquiry Concerning the Principles of Morality (EPM) contend that morality is grounded in sentiment, with reason playing an important, but secondary, role in moral life. Reason's basic moral contribution is to reveal facts that can show us ways of achieving certain desirable ends and avoiding certain undesirable actions. However, the ends themselves come to life through sentiments of approval or disapproval which can move us to act in one way or another. Reason alone does not determine these ends. In the final analysis, it is sentiment, not reason, that grounds moral values and action. Without moral sentiments among humans, there is no moral work for reason to do.

For Reid, too, moral sentiments are essential for morality. However, in seeming contrast to Hume, these sentiments include reason within their structure, as their make-up includes moral judgments, which involve conceptualizations that only rational creatures can have.