It is common for incompatibilists to say that their conception of free will (as requiring the ability to do otherwise in exactly the same conditions) matches everybody's intuitions and that compatibilism is a philosopher's trick based on changing the definition. Dennett is arguing that, contrary to this, what actual people in actual circumstances do when they want to know if someone was "free to do otherwise" is never to think about global determinism; rather, as compatibilism requires, they think about whether that person (or relevantly similar people) actually does/do different when placed under very similar (but not precisely identical) conditions.