one cannot write about conceptual art

The statement eventually means that one cannot write only about the how of the term "concept art" (in other words: it cannot be defined). If it is true that meaning is in using, then concept art is using the art-concept in an artistic context, i.e. it is the art-concept itself. Thus I can only write: concept art is concept art (or concept art is not concept art) - appropriately to the nature of the movement, instead of a definition I arrive at tautology. I can only propose that we should use the expression, or at least I will use it.

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