Contemporary epistemology has explored the notion of a hinge commitment as set out in Wittgenstein’s final notebooks, published as On Certainty. These are usually understood as essentially groundless certainties that provide the necessary framework within which rational evaluations can take place. John Greco has recently offered a striking account of hinge commitments as a distinctive kind of knowledge that he calls ‘common knowledge’. According to Greco, this is knowledge that members of the community get to have without incurring any epistemic (...) burden, and as such is fundamentally different from other kinds of knowledge. I offer a critique of Greco’s proposal. While I agree that there is a variety of knowledge that counts as common knowledge, I contend that it is not to be understood as knowledge that one gets for free as Greco suggests. Moreover, I argue that our hinge commitments do not count as common knowledge—either in Greco’s sense of the term or in the alternative manner that I set out—because properly understood they are not in the market for knowledge at all. In defence of this claim, I suggest that Greco’s conception of a hinge commitment is both missing some crucial elements and also too broad in its extension, in that it encompasses both instances of common knowledge and hinge commitments proper. (shrink)