Full Idea
Peacocke argues that it may be a condition of possessing a certain concept that one be fundamentally committed to certain propositions which contain it. A concept is constituted by playing a specific role in the cognitive economy of its possessor.
Gist of Idea
Concepts are constituted by their role in a group of propositions to which we are committed
Source
report of Christopher Peacocke (A Study of Concepts [1992]) by John Greco - Justification is not Internal §9
Book Reference
'New Essays on the A Priori', ed/tr. Boghossian,P /Peacocke,C [OUP 2000], p.164
A Reaction
Peacocke is talking about thought and propositions rather than language. Good for him. I always have problems with this sort of view: how can something play a role if it doesn't already have intrinsic properties to make the role possible?