A treatise of humean nature

A strong version of the Humean theory of motivation (HTM) that includes two theses is defended here. First, desire is necessary for action, and no mental states are necessary for action other than a desire and an appropriate means-end belief. Second, desires can be changed as the conclusion of reasoning only if a desire is among the premises of the reasoning. Those who hold that moral judgments are beliefs with intrinsic motivational force cannot accept HTM, even as a contingent truth, since HTM implies that no beliefs have intrinsic motivational force. Many of them argue that there are cases where HTM fails to explain how we deliberate. The response is to develop a novel account of desire and show that HTM provides superior explanations even in their cases. On this account, desire necessarily motivates action when combined with an appropriate means-end belief. Desire necessarily causes pleasure when our subjective probability of satisfaction increases or when we vividly imagine satisfaction, and likewise causes displeasure when the subjective probability of satisfaction decreases or when we vividly imagine dissatisfaction. It is contingently true that desire directs attention towards things one associates with its object, is made more violent by vivid sensory or imaginative representations of its object, comes in the two flavors of positive desire and aversion, and satisfies the second principle above. This account of desire helps HTM provides superior explanations of deliberation even in the cases that its opponents offer as counterexamples. In response to Darwall’s proposed counterexample to the second principle and some 20th century writers discussing the feeling of obligation, it is shown that Humeans can provide superior explanations of agents’ emotions in their cases. In Searle’s case of akrasia, Scanlon’s case of bracketing, and Schueler’s case of deliberation, it is shown that Humeans can build the structures of deliberation more simply than their opponents can. Against Korsgaard, it is argued that agents cannot choose the aims for which they act.