Hume begins his discussion “Of the influencing motives of the will” (T2.3.3) by noting that most moral philosophy, both ancient and modern, is founded on the idea that there is a “combat of passion and reason,” and that a person is virtuous only in so far as reason is the victor in this combat (T2.3.3.1: 413). On this view, we “ought to oppose” our passions by way of reason. In criticizing this view Hume argues that “reason alone” is impotent, and that therefore it can never act in opposition to our passions. Also, that calm passions are mistaken for reason. To the extent that there is anything like a combat which characterizes our moral life it is really a conflict between “calm passions” and violent ones. But, as we shall see, Hume's own moral theory tends to downplay any such combat. Moral feelings are a subset of calm passions which can, at least in principle, overcome our violent passions “without… opposition” (T2.3.4.1: 419).

The theory that Hume attacks in this section is clearly Platonic. In Book 4 of the Republic Plato wrote of a “civil war of the soul” and argued that it is “appropriate for the rational element to rule” over the spirited and desiring parts of the soul. More directly, Hume is concerned with modern theories such as those of the Newtonian philosopher Samuel Clarke, who wrote that virtue is founded in