Lately one popular line of objection to contextualism about the concept of knowledge, and to contextualist-based replies to radical skepticism about knowledge, is to claim that contextualism is committed to an implausible thesis that ordinary users of the concept of knowledge are "blind" to the semantical workings of this concept. Our reply is to this effect: the kind of error they are prone to is a subtle and predictable "competence-based performance error", and the fact that contextualism is committed to saying that folks are prone to that kind of error is not a strong objection against the theory.