Psychology and Obligation in Hobbes: The Case of “Ought Implies Can”

Many interpreters use Hobbes’s endorsement of “ought implies can” to justify treating Hobbes’s motivational psychology as an external constraint on his normative theory. These interpreters assume that, for Hobbes, something is “possible” for a person to do only if they can be motivated to do it, and so Hobbes’s psychological theory constrains what obligations people have. I argue this assumption about what is “possible” is false and so these arguments are unsound. Looking to Hobbes’s exchange with Bramhall on free will, I argue that the sense of “possible” relevant for “ought implies can” in Hobbes’s philosophy only concerns an agent’s capacity to do something if they decide to do it. Whether a person can be motivated to do something, then, does not determine if it is possible for them. Consequently, Hobbes’s motivational psychology cannot determine what our obligations are by invoking the principle that “ought implies can.”