I need some clarification on two instances of what seem to me question begging. The first example is from moral philosophy; the second, aesthetics.
1. You and I are in dialogue about the viability of a certain moral theory. Neither of us is committed to a particular theory, so we are quite open to accepting what seems to us the ‘best’ theory available. We have no commitments about good and evil, right and wrong; we are looking for a theory that will tell us what good and bad, right and wrong are. In essence, we are committed to not prejudging the matter a priori. I propose a theory, describe its principles in detail, and we exam what it permits, forbids, etc. You respond that this theory is deficient because it permits infanticide and baseless murder.
2. Once again committed to neutrality, this time about what counts as art and what doesn’t, we are now examining a theory of art. This theory disallows certain ‘paradigmatic works of art’ into the canon. For the sake of argument, let’s say that it excludes readymades like Duchamp’s Fountain, all of Pollock, and all art expressly meant to inspire religious devotion. You object that this is obviously a deficient theory of art because it excludes what are obviously pieces of art.
In both of these cases, you have begged the question, right? You have assumed in the first example that infanticide and baseless murder are wrong or immoral (and thus you have presupposed a normative framework that renders these judgments). In the second example, you have presupposed that what has been accepted in the art world actually is art. This presupposes that the art world already has a valid theory of art (or that the art world is precisely what decides the this matter by decree). In either case you have already accepted that a valid theory of art already exists, but this is precisely what our dialogue in example 2 is trying to determine.
Am I missing something here? I ask because I often run across this form of reasoning in survey texts that introduce the available theories of art or ethics.