How do instructions help us make rational decisions?

Abstract On one plausible story about how we rationally acquire reasons for action, an individual rationally acquires a new reason to ϕ only if there is something that individual learns about the world. It can also be said without much of a doubt that, in talking to each other, we sometimes rationally acquire reasons for action. This combination of claims is easy to square with declarative sentences, which we clearly use to provide each other with information when we make assertions. But it is much harder to square with imperative sentences, which are standardly taken not to be used in this way. How is it that in attempting to change someone’s behavior by giving them an instruction, we manage to acquaint them with reasons to act? Here, I offer a novel way out of this puzzle: instructions, I argue, are much more like assertions than we ordinarily take them to be, including in their being used to provide each other with information. Whereas assertions provide us with information about any arbitrary aspect of the world, instructions provide us with information specifically about what it is rational to conclude in the course of some practical inquiry, given our goals and the available evidence.