Many of the earliest definitions of art were probably intended to emphasize salient or important features for an audience already familiar with the concept, rather than to analyse the essence possessed by all art works and only by them. Indeed, it has been argued that art could not be defined any more rigorously, since no immutable essence is observable in its instances. But, on the one hand, this view faces difficulties in explaining the unity of the concept – similarities between them, for example, are insufficient to distinguish works of art from other things. And, on the other, it overlooks the attractive possibility that art is to be defined in terms of a relation between the activities of artists, the products that result and the audiences that receive them.
Two types of definition have come to prominence since the 1970s: the functional and procedural. The former regards something as art only if it serves the function for which we have art, usually said to be that of providing aesthetic experience. The latter regards something as art only if it has been baptized as such through an agent’s application of the appropriate procedures. In the version where the agent takes their authority from their location within an informal institution, the ‘artworld’, proceduralism is known as the institutional theory. These definitional strategies are opposed in practice, if not in theory, because the relevant procedures are sometimes used apart from, or to oppose, the alleged function of art; obviously these theories disagree then about whether the outcome is art.
To take account of art’s historically changing character a definition might take a recursive form, holding that something is art if it stands in an appropriate relation to previous art works: it is the location of an item within accepted art-making traditions that makes it a work of art. Theories developed in the 1980s have often taken this form. They variously see the crucial relation between the piece and the corpus of accepted works as, for example, a matter of the manner in which it is intended to be regarded, or of a shared style, or of its being forged by a particular kind of narrative.