 The last response to the reductio is to deny that the argument is a reductio at all. Instead, this compatibilist embraces that EXT and SK facilitate armchair knowledge of the world. Some externalists have even offered independent arguments to that effect (Putnam 1981). But these independent arguments are significantly more complex, having to do with model theory and Skolem’s “paradox.” Such things shall not be discussed here (but see the entry on  skepticism and content externalism).