Over the centuries, the bourgeois view of art has entangled itself in three curious chains. The first insists that works of art be one-of-a-kind productions - that anything duplicated or mass produced is mere craftsmanship. The second demands that each work be executed by a single individual - that collaborative efforts, however powerful, stink of commercialism. The third, quite simply, is that art, to be art, must be expensive.
Overturning such silly shibboleths, the exhibition of 20th-century prints now at the Museum of Fine Arts is required viewing. Here is evidence that some of the century's finest art is duplicate, collaborative, and relatively inexpensive. Here is proof that a body of prints can touch all the major developments of modern painting. Most important, here is a collection to intrigue, offend, puzzle, and delight anyone giving it time and attention.
The 250 pieces in ''The Modern Art of the Print: Selections from the Collection of Lois and Michael Torf'' (Aug. 1 through Oct. 14), drawn from what museum director Jan Fontein calls ''the finest private collection of modern prints in America,'' reflect the discerning eye of Weston, Mass. collector, Lois Torf. Beginning with Munch's ''Vampyr'' and Nolde's ''Junge Danin'' (''Young Danish Woman''), it moves through the Expressionism of Kirchner and Schiele and the Cubism of Braque and Picasso to the Constructivism of Lissitzky and Gabo. Worth lingering over are the 12-piece set of Kandinsky's ''Kleine Welten'' (''Little Worlds''), the buoyant splash of Miro's ''L'Equinoxe'' (''The Equinox''), and most of Picasso's formidable intricacies.
And that's just the trunk. Out of it, in the recent renewal of printmaking, a thousand branches have sprung - bending backward into lithography, forward into photography, and sideways into collage. Here are works by Johns, Rauschenberg, Oldenburg, Warhol, Lichtenstein, Hockney, and Dine; here is Motherwell's suddenly realized ''Automism A'' and Frankenthaler's inspired ''Savage Breeze.'' The last part of the show, with newer works mainly by European artists, proves that printmaking is still charged with energy. Don't miss a smaller exhibition in the newly dedicated Torf Gallery downstairs, ''Ten Painters & Sculptors Draw'' - especially Dine's ''The Key West Shell'' and Lichtenstein's ''Collage for Brushstroke Sculpture.''