 Emily Sullivan, for instance, claims that even if we grant that understanding involves abilities, it does not follow that there is something special about understanding from a psychological point of view, because ordinary propositional knowledge itself requires abilities (Sullivan 2018). Thus I can apparently only know that the traffic light is red, in the actual world, if I would have gotten the color right in close possible worlds as well. More generally, knowing seems to require the ability to track the truth about the world, so that when the world changes, my cognitive attitude about the world changes with it. But this ability to be responsive to changing conditions is not obviously anything exotic, and it does seem to entail that the object of the mind is not a proposition (that the traffic light is red seems like a paradigm example of a proposition, after all).