(NPR) - In Don Quixote, Cervantes tells the story of two brothers who claim to be excellent judges of wine.

They are given a wine to taste and each pronounces it excellent. One brother notes, however, that its perfection is marred by a vague taste of leather. The other disagrees, observing that the only flaw is a faint but distinct trace of iron. These criticisms are dismissed, but the brothers are later vindicated, for when the keg is finished, it is discovered that there is a key on a leather string resting at the bottom.

Hume, the great Scottish philosopher, retells this story to make the case for the importance of delicacy of taste and refinement in discrimination, whether in the domain of wine or art.

Connoisseurship of this sort, however, is in bad repute these days. An article published in the Guardian last summer titled reviews studies purporting to show that when it comes to wine, even the experts are unreliable guides. It isn't just that they disagree among themselves in the values and qualities of wines; they disagree with themselves from one minute to the next in evaluating the very same wine poured from the very same bottle. (See philosopher and oenophile Barry Smith's essay in for a convincing and informative reply to the arguments raised in the article. See for my own previous go at the issues.)

Connoisseurs in the world of art, some conclude, fare no better. As a case in point, consider the latest forgery fiasco: A man working alone in a garage in Queens produced abstract expressionist works that fooled the experts and entered the art market as if they were authentic. The art critic Blake Gopnik, writing in , sums up the current state of affairs this way: