The Humean Theory of Motivation

The thesis that motivation always requires a desire, since belief alone cannot move us to act.

Definition

The Humean theory of motivation holds that every motivating reason for action consists of a belief paired with a distinct, non-derivative desire, and that beliefs by themselves — having a mind-to-world direction of fit — cannot motivate action.

Scope

This topic covers the Humean theory of motivation — that intentional action is produced by a belief together with an independent desire, and that beliefs are motivationally inert on their own. It examines the theory's role in metaethics, where combined with cognitivism and judgement internalism it generates 'the moral problem', and the anti-Humean alternatives that posit besires or claim some beliefs can motivate directly.

Core questions

• Can a belief motivate action without an accompanying desire?
• What is the 'direction of fit' between belief and desire?
• Does the Humean theory rule out moral judgements that are both beliefs and intrinsically motivating?
• Are 'besires' or anti-Humean motivating states coherent?

Key concepts

• direction of fit
• belief-desire model
• motivational inertness of belief
• besire
• the moral problem

Key theories

Humean belief-desire model

Motivation requires two states with opposite directions of fit: a belief representing the world and a desire to change it; reason alone is inert, so only desire originates action.

Anti-Humean motivation

Some hold that recognizing a reason (a belief) can itself motivate, or that there are 'besires' combining both directions of fit, allowing moral cognition to move us without a prior desire.

History

The theory descends from Hume's claim in the Treatise (1739) that reason is and ought to be the slave of the passions. Nagel's The Possibility of Altruism (1970) mounted a major anti-Humean challenge, and Smith's 'The Humean Theory of Motivation' (1987) gave the modern canonical statement using the direction-of-fit framework.

Debates

Whether belief can motivate

Anti-Humeans argue moral and prudential beliefs can motivate directly, citing the practicality of moral judgement; Humeans reply that any apparent case includes a desire, and that the direction-of-fit argument shows belief is inert.

Generating the moral problem

Combined with cognitivism and internalism, the Humean theory yields an inconsistent triad, forcing a choice among denying internalism, denying cognitivism, or rejecting the Humean theory.

Key figures

• David Hume
• Michael Smith
• Thomas Nagel

Seminal works

• hume1739
• nagel1970
• smith1987

Frequently asked questions

What is 'direction of fit'?

It is a metaphor for how a mental state relates to the world. Beliefs aim to fit the world (and are revised if they do not), while desires aim to make the world fit them. The Humean theory uses this contrast to argue that only desires can motivate.