Hinges in the knowledge economy: On Greco’s common and procedural knowledge

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.