  A common family of arguments, inspired by Wittgenstein’s famous remarks about games (Wittgenstein 1953), has it that the phenomena of art are, by their nature, too diverse to admit of the unification that a satisfactory definition strives for, or that a definition of art, were there to be such a thing, would exert a stifling influence on artistic creativity. One expression of this impulse is Weitz’s Open Concept Argument: any concept is open if a case can be imagined which would call for some sort of decision on our part to extend the use of the concept to cover it, or to close the concept and invent a new one to deal with the new case; all open concepts are indefinable; and there are cases calling for a decision about whether to extend or close the concept of art. Hence art is indefinable (Weitz 1956). Against this it is claimed that change does not, in general, rule out the preservation of identity over time, that decisions about concept-expansion may be principled rather than capricious, and that nothing bars a definition of art from incorporating a novelty requirement.