Abstract

In his “Common knowledge” (2016) and _The Transmission of Knowledge_ (2021), John Greco proposes a novel account of hinge propositions. Central to it is the idea that they are items of common knowledge – that is, of knowledge that is already present in the system, freely available to anyone, without having to figure it out by oneself or having to be taught it by others. As such, they are not subject to any quality control at all. Furthermore, they figure in a subject’s cognitive economy as items of procedural, mostly tacit knowledge, which is operative in the execution of actions and various cognitive tasks. After introducing the basics of Greco’s account, I consider it from a systematic and historical perspective and argue that, while instructive, it is wanting in several respects. Whereas some, among the myriad hinges Wittgenstein considers in _On Certainty_ (1969), may be known, there is no need to make them the content of a different kind of knowledge. Furthermore, we cannot have (evidential) justification and, _a fortiori_, knowledge of at least some other propositions that Wittgenstein considered as hinges. In passing, I also show that Greco’s account aligns much more with G. E. Moore’s ideas about the epistemic status of his truisms in “A defence of common sense” (1925) and the premises of his celebrated “Proof of an external world” (1939), than with Wittgenstein’s account of hinges and their epistemic significance in _On Certainty_.