  Consider an analogy (Dretske 1998). Gus inserts a quarter into a vending machine. The coin has a range of intrinsic qualities common to quarters, but its being a quarter does not depend solely on these intrinsic qualities: a quarter’s intrinsic qualities would be shared by a decent counterfeit. The coin’s being a quarter depends on its having the right sort of history: it was produced in a United States mint. This is something the vending machine cares nothing about. The machine reacts only to the coin’s intrinsic features. You might put this by saying that the coin affects the machine, not qua quarter, but only qua possessor of a particular kind of intrinsic makeup. (Vending machines are built to take advantage of the contingent fact that objects with this intrinsic makeup are almost always quarters.)