Weitz criticizes theories that attempt to determine the nature of art through definitions based on necessary and sufficient conditions. His concern is that such closed definitional approaches aim to prescribe the essence of art in an exclusivist way. According to him, essentialist theories exclude alternative definitions and try to formulate a single, perfect statement by objectively defining the properties of all art. However, Weitz argues that these theories, which claimed to provide the correct definition of the nature of art, fundamentally stem from a mistaken understanding of the concept of art. Instead, he maintains that art is an open concept, one that cannot logically possess any set of necessary and sufficient conditions.

Weitz insists that the central question should not be “What is the essence of art?” but rather “What kind of concept is art?” This argument is grounded in the later Wittgenstein’s theories of language-games and family resemblance. Wittgenstein’s approach made it possible for Weitz to argue this way, because instead of attempting to identify commonalities that determine the necessary and sufficient conditions of a term X, Wittgenstein investigated how X is actually used within our language—focusing on the conditions of use themselves.

A full explanation of Wittgenstein’s theory of language-games and family resemblance would go beyond the scope of this summary, but the key point is as follows: words, or language, arise from our forms of life and are learned or acquired through use. In other words, concepts cannot be perfectly structured or strictly defined as in logic or mathematics. Put differently, unless we arbitrarily restrict the scope of their usage, concepts remain open to constant revision and reinterpretation. Thus, the concept of art is an “open concept”: one whose conditions of application can always be modified or corrected. Art, therefore, is not to be grasped in terms of essence, but rather understood, described, and explained through resemblances.

Weitz’s theory of the open concept of art—or his thesis on the indefinability of art—thus derives from Wittgenstein’s notion of resemblance. Importantly, he does not claim that art cannot be defined at all. Rather, he stresses that any definition of art is never fixed by nature and that one must take a critical stance toward the act of fixing it. Since definitions of art are always subject to change, whether by individuals or by society, art cannot have an immutable definition.

Yet, his reliance on the impossibility of necessary and sufficient conditions as a key premise also becomes the central reason why his theory is sometimes seen as contradictory. Noël Carroll, for example, criticizes Weitz’s position as leading to a fatal skeptical conclusion that “everything is art.” Furthermore, if something counts as art merely because it resembles previous works of art (to put the resemblance theory simply), then radically innovative works such as Duchamp’s Fountain or John Cage’s 4’33’’—which bore little resemblance to prior art—could never have been classified as art at the time of their emergence. Carroll further argues that if one introduces special conditions in order to avoid such skepticism, the argument contradicts the very premise of the open concept of art, namely that necessary and sufficient conditions are unnecessary. For this reason, he concludes that the open concept thesis is not logically sustainable.

Summary

Morris Weitz argued that art cannot be defined in terms of necessary and sufficient conditions. Building on Wittgenstein’s theory of resemblance, he maintained that art is an open concept, and therefore cannot be captured by a single essentialist definition.