Though Timothy Williamson (2000) argues that we are not always in a position to know the phenomenal character of our experiences, critics retort that his argument overlooks views according to which the phenomenal properties involved in our experiences can serve to constitute our knowledge of their phenomenal character. I develop an argument against this view, contending that the phenomenal knowledge these critics envision would lack an adequate conceptual role: one who possessed such knowledge would nevertheless have no grasp of what it entailed or ruled out. At best, therefore, this knowledge cannot serve the foundational role its proponents imagine for it; and at worst, it will not count as knowledge at all. The upshot is that the best defense against Williamson turns out not to secure our epistemic foothold in the phenomenal realm.