As the ur-postmodernist, Warhol’s entire artistic practice and persona stood, quite intentionally, in opposition to modernist ideas. He was the very antithesis of a Van Gogh, a Picasso, a Pollock. Where they (it was held) re-made the world visually and emotionally in the smithies of their tortured souls (to paraphrase James Joyce), Warhol blithely swiped subject matter from mass media. He presented himself as a kind of empty mirror for the images that were already all around us in advertising or entertainment or packaging. And his persona was famously cool and withdrawn, or even blank: just the opposite of the outsized, impassioned personalities of Picasso or Pollock.
But the The Andy Warhol Foundation for the Visual Arts and the Andy Warhol Art Authentication Board treat Warhol and his works with the traditional veneration accorded to the modernists (and their predecessors).
Yet remarkably, the entire discourse and institutional context which was developed in relation to Manet, Kandinsky or de Kooning, and explicitly attacked by Warhol and the postmodernists, is simply reproduced by the foundation, the board, and indeed by virtually all institutions that deal with postmodern art. It’s roughly analogous to scientists trying to account for the latest results in physics using the intellectual equipment of medieval theology.
If art really is over, as Warhol's practice proclaimed, then even "authentic" Warhols–whatever they are, as many of his works were executed entirely by assistants–aren't worth much.