Quote - I disagree. If someone claims something is art, ask them why it's art. If their reply is along the lines of  "because I say so", then you can dismiss it. There is a difference between any old claim and a supportable claim.

Phantast, I mean no offense but what causes you to make this claim? It is not at all evident to me what the basis for it is??? "There is a difference between any old claim and a supportable claim." How is this true? In that one is more compelling than another, not that one is more true than another? Why can you dismiss the claim if someone justifies it only with "because I say so". I might only be able to defend my belief that the earth orbits the sun by saying "because I say so" but that would have no baring on whether the statement was true. One can not demand rational criteria for the the defense of claims that have no rational basis.

If I sit on a milk crate and declare it is a chair few would argue with me even though the object was not made with the intention I might... I could say of a giant inaccessible rock formation or a tiny sculpture that they are chairs despite the fact that they could never be used as such. The case remains that I can unilaterally declare something a chair based on my perception of function, resemblance or intention and all that could be argued is whether it is a good chair or a bad chair, a chair you respect or a chair you dismiss or despise.

Some things are defined by terms, perhaps a cat, although that is not truly so straight forward, other things are not defined categorically although they may seem to be, a loud noise, a nonsense or a nuisance, a chair, a table... Something may seem a table to me and not to you, it may seem somewhat a table or very much a table or even hardly a table at all to me while still being a table for any number of reasons. Its classification can not be disputed other than as a quantitative or qualitative matter as opposed to a categorical imperative. A rock is defined categorically but a thing defined by utility, resemblance, or tradition can not. If I say that in Egypt a cushion is a chair can anyone make a sensible argument it is not other than to say "because I say so"?

It is like the "solution" to xeno's paradox which claims motion is impossible because for motion to take place a thing must traverse an infinite number of points in a finite time.... this is an error of category, motion and the conceptual construct of a point are categorically different and are not reconcilable in this case although they might seem to be in the hazy terms of normal life.. issues of categorical rather than functional definition can not be compared coherently, they are apples and oranges... this does not even attend to matters of faith. To be an artist is to have faith in art or money as far as I can tell.  Wittgenstein discusses at length the fallacies derived from errors in category and the false metaphors derived from grammatical syntax, the structure of language.

N.B. I don't take my deepestly held belief too seriously myself so again please don't see this as a personal attack :)