A spirited, thoroughgoing deconstruction--responsible, if extravagantly partisan--of Marcel Duchamp's bohemian life and bizarre oeuvre, which formalist critics dismiss as monumental hype and postmodernists (""worshippers at the shrine of St. Marcel"") revere. New Yorker art columnist Tomkins (Post to Neo: The Art World of the 80's, 1988, etc.), argues (persuasively) that the artist's serial rejections--of the eye, the hand, the traditional, the subjective--changed the language of 20th-century art; he also argues (reductively) that they made Duchamp (not Matisse, not Picasso) its dominant influence. Tomkins traces the progress of Duchamp's idea of art-making from an ""anti-retinal"" activity of the mind (as with Nude Descending a Staircase, in which he contrived to paint motion), to an actualization of ""the beauty of indifference,"" the essence of Duchamp's aesthetic (per his Readymades, or signed found-objects). In the culture of Paris avantgarde that spawned Duchamp's conceptual metamorphoses, playwrights and poets figure as prominently as fellow visual artists: Tomkins singles out Jarry for his anarchism, LaForgue for his ironies, and Raymond Roussel for his exaltation of chance. Confident that Duchamp ""opened more doors than he closed,"" Tomkins has no disbelief to suspend. And so he welcomes Duchamp's cavalier self-contradictions as evidence of his ""affirmative irony."" At the outset Tomkins calls his subject ""the ultimate escape artist""--and for all the subsequent accretion of biographical detail, Duchamp remains elusive. Which is in keeping, in a way, with the cultivated detachment that governed his multiple incarnations (debauchee on the run from WW I, chess pro in retreat from the art scene, accomplished parasite reluctant to profit directly from his art, eventual husband in spite of himself). Duchamp is certainly sui generis, for better and also for worse. Tomkins, determined to make the very best of him, rises to an audacious challenge.