I argue that entertaining a proposition is not an action. Such events do not have intentional explanations and cannot be evaluated as rational or not. In these respects they contrast with assertions and compare well with perceptual events. One can control what one thinks by doing something, most familiarly by reciting a sentence. But even then the event of entertaining the proposition is not an action, though it is an event one has caused to happen, much as one might cause oneself to see a book by looking at it. I also discuss how this may support the view that thinking about the world is a source of information about it.