Of Course there are legitimate and serviceable closed concepts in art. But these are always those whose boundaries of conditions have been drawn for a special purpose. Consider the difference, for example, between "tragedy" and "( extant) Greek tragcdy. " The first is open and must remain so to allow for the possibility of new conditions, e.g., a play in which the hero is not noble or fallen or in which there is no hero but other elements that are like those of plays we already call "tragedy." The second is closed. The plays it can be applied to, the conditions under which it can be correctly used are all in, once the boundary, "Greek," is drawn. Here the critic can work out a theory or real definition in which he lists the common properties at least of the extant Greek tragedies. Aristotle's definition, false as it is as a theory of all the plays of Aeschylus, Sophocles, and Euripides, since it does not cover some of them, properly called "tragedies," can 7 be interpreted as a real (albeit incorrect) definition of this closed concept; although it can also be, as it unfortunately has been, conceived as a purported real definition of "tragedy," in which case it suffers from the logical mistake of trying to define what cannot be defined—of trying to squeeze what is an open concept into an honorific formula for a closed concept.
What is supremely important, if the critic is not to become muddled, is to get absolutely clear about the way in which he conceives his concepts; otherwise he goes from the problem of trying to define "tragedy," etc., to an arbitrary closing of the concept in terms of certain preferred conditions or characteristics which he sums up in some linguistic recommendation that he mistakenly thinks is a real definition of the open concept. Thus, many critics and aestheticians ask, "What is tragedy?," choose a class of samples for which they may give a true account of its common properties, and then go on to construe this account of the chosen closed class as a true definition or theory of the whole open class of tragedy. This, I think, is the logical mechanism of most of the so-called theories of the sub-concepts of art: "tragedy," "comedy," "novel," etc. In effect, this whole procedure, subtly deceptive as it is, amounts to a transformation of correct criteria for recognizing members of certain legitimately closed classes of works of art into recommended criteria for evaluating any putative member of the class.