I was just reading an article, "Young at Art", from the Sunday Times Supplement (2/12/2007). The main part of the article was about how the paintings of a young girl of four had been fetching prices of about 300,000 dollars. Later, some evidence came to light which seems to indicate that it was not simply all the girl's unaided, unprompted work. However, it does raise the question of how the value of items of art can be established - which also raises the question of how they can be understood, particularly if they are non-figurative.
It seems to me that an important tool is to apply the same rules to understanding art that you would apply to understanding humour. Much of the best modern work – that I believe is liable to last – I would associate with inventiveness and a sense of fun (whether or not ostensibly meant so by the artist). A joke shares something with a work of art: it twists things so that you look at them in a new light, often juxtaposing things that you would not normally think of as going together. In this light, Damian Hurst's diamond-coated skull can be thought of as a rather obscene joke about the art market - and how much some art collectors are prepared to pay - rather than a profound statement about death. The crack in the floor of the Tate Modern works well as a visual joke - which is why it appears to be attracting many fascinated visitors - but perhaps not so well as a deep statement about the separation of developed and under-developed countries and alienated minorities.
Jokes - like art - can be thought-provoking, witty, simple or complex, cynical, satirical, in good or bad taste, offensive, upsetting, re-assuring and - sometimes - just plain bad! I think that this way of understanding art is obtained from one's first reaction to the piece - without reference to what the artist might say about it. Just a feeling about what the piece is saying based on what the piece looks like, the materials it is known to have be made from and the context within which it is presented. Looked at like this, Duchamp's ready-made "Fountain" (a ceramic urinal which he signed (R. Mutt"), can be understood as being a work of art, but also a rather unpleasant and deliberately offensive joke on the art-going public of the time (1917).
If you decide that you appreciate the "joke", it is then worth considering other factors in order to decide if its purchase (presuming it is purchasable) represents value for money. In a recent TV programme about the Frieze Art Fair (“Imagine: How to Get On in the Art World”), the presenter, Alan Yentob, bought a sculpture, one of an edition of three, by George Henry Longley, at £3,500. It represents a play on the idea of a ladder. Longley transformed it by sealing off the ends and changing the five rungs by using a diamond cross-section. The final piece in, presumably, welded metal is painted bright red. When you take it that the dealer is probably getting at least half of the final price and taking into account the difficulties of making the piece, the cost does not seem unreasonable. Displayed against a white wall in a room of Alan Yentob's house, the ladder made a striking display and, to me at least, made art historical connections with a whole type of contemporary art. Hence I think that it was a very reasonable, if not earth-shattering, purchase. Witty enough to be interesting and decorative enough to work in the context of a private house. Not the sort of work that I would want for myself, but one that I can appreciate in someone else's house.
The big question, I think, is to establish whether or not you can laugh with the work of art, or whether the joke is on you!