Full Idea
Dickie's institutional theory of art says that something is a work of art if and only if it has had that status conferred on it by a competent member of the artworld.
Gist of Idea
The institutional theory says only a competent expert can decree something to be an art work
Source
report of George Dickie (Introduction to Aesthetics [1997], Ch.8) by Sebastian Gardner - Aesthetics 3.1
Book Reference
'Philosophy: a Guide Through the Subject', ed/tr. Grayling,A.C. [OUP 1995], p.613
A Reaction
The idea that a single 'competent' person can do this sounds daft, and probably circular. A consensus in the artworld sounds more plausible, but this still leaves the revolutionary genius, who - in retrospect - produced unrecognised 'art'.