 Hume famously sets himself in opposition to most moral philosophers, ancient and modern, who talk of the combat of passion and reason, and who urge human beings to regulate their actions by reason and to grant it dominion over their contrary passions. He claims to prove that “reason alone can never be a motive to any action of the will,” and that reason alone “can never oppose passion in the direction of the will” (T 413). His view is not, of course, that reason plays no role in the generation of action; he grants that reason provides information, in particular about means to our ends, which makes a difference to the direction of the will. His thesis is that reason alone cannot move us to action; the impulse to act itself must come from passion. The doctrine that reason alone is merely the “slave of the passions,” i.e., that reason pursues knowledge of abstract and causal relations solely in order to achieve passions’ goals and provides no impulse of its own, is defended in the Treatise, but not in the second Enquiry, although in the latter he briefly asserts the doctrine without argument. Hume gives three arguments in the Treatise for the motivational “inertia” of reason alone.