IN today's art world, Hans Haacke may be not only inevitable but also indispensable.
With the money now invested in art, with the growing corporate and political involvement, with a new breed of collector who approaches art as something to display, like jewelry, or barter, like stocks, it is logical that some artists want no part of art making as usual.
Of the artists who are determined to preserve their independence, to define art within a social and political context - and to ask, what is it about art and its institutions that is so attractive to political and business interests? - Haacke is the most influential. His mixed-media works are consistent, meticulous, witty and perverse. They are puritanical. They are not flexible. They are not about empathy and doubt.
One of Haacke's urgent concerns is the expanding relationship between corporations and museums. Another is the business ventures of major collectors and patrons in countries like South Africa. In the 1985 ''Buhrlesque,'' his and hers shoes, each with a candle pointed upward out of the heel like an antiaircraft gun, sit on an altarlike table. Hanging on the wall behind the table, like a devotional image in a cheap motel, is a cover of Paratus, the periodical of the South African Defense Force. The person who inspired the work is Dietrich Buhrle, whom Haacke describes as a prominent Swiss art collector, a supporter of the Kunsthaus in Zurich and the chairman and chief executive officer of a company that makes shoes and arms that supply the South African Government.
''Hans Haacke: Unfinished Business,'' at the New Museum of Contemporary Art, is the first American museum show of the 50-year-old German-born artist, who has been living in New York since 1965. The 12 pieces span the last 15 years. The earliest is ''Shapolsky et al. Manhattan Real Estate Holdings, a Real-Time Social System, as of May 1, 1971,'' the work that caused the cancellation of Haacke's scheduled exhibition at the Solomon R. Guggenheim Museum in 1971. This endless piece includes 142 photographs and data sheets and six charts detailing the holdings of a particular New York real-estate empire. When the Guggenheim learned of the piece, Thomas Messer, the director of the museum, wrote the artist that museum policies ''exclude active engagement towards social and political ends.''
Haacke's work has changed a great deal since then. At its best it has a freshness and punch that was characteristic of the most radical 1960's art. One of the sparest and most pointed works in the show is ''On Social Grease.'' It consists of six photo-engraved metal plates - like honorary plaques or ancient tablets - with statements about art by political and corporate executives written into them.
The exhibition also includes the theatrical ''MetroMobiltan.'' Three banners - like the banners over the facade of the Metropolitan Museum of Art - hang down from what looks like a fragment of the Metropolitan's front cornice. Two banners include statements from the Mobil Corporation about its involvement in South Africa; the third announces an exhibition on African art Mobil supported. Behind the banners is a photomural of a funeral in South Africa for black victims. Both the cornice and the altarlike platform beneath the banners are Fiberglas. The banners and the Fiberglas create the sense of something trying to lift the weight of the subject matter. Clearly, Haacke, like other Conceptual artists for whom he is an example, makes political art in part in order to feel he can breathe.
One of Haacke's targets is Charles Saatchi, a powerful collector of contemporary art and trustee of the Tate Gallery in London who recently opened his own museum in that city. Charles and Maurice Saatchi are the founders of Saatchi & Saatchi, perhaps the largest advertising agency in the world. ''Global Marketing'' is a large black cube on which Haacke has documented in black letters the scope of Saatchi's business involvements in South Africa. The black on black recalls the tough, 1960's black-on-black paintings of Ad Reinhardt, but in Haacke's work the glossy black on matte black also suggests a tuxedo. The box builds on the deathly quality of Tony Smith's black cubic sculpture ''Die.''
The strengths and limitations of Haacke's work have a great deal to do with its 1960's roots. Like Minimalist art, Haacke's work suggests a visceral reaction against the personal and metaphysical emphasis of the late 40's and 50's. As with boxes of Donald Judd, there is a sense that Haacke's pieces simply exist. They seem to have come out of nowhere, to have emerged impersonal, immaculate and intact.
The subject matter appears to be totally ''outside'' the work; that is to say, the works reflect the history around them while appearing not to have any history of their own. Indeed, Haacke's work vehemently rejects any notion of a private, or ''inside'' world - which for many political artists is identified with private property and with the kind of private and ''pure'' esthetic experience that has had such public-relations value for corporations. If the Formalist art of the 60's asked to be approached solely within the language of art, Haacke's art asks to be approached solely in political terms.

The purity and absoluteness of Haacke's own work therefore leads to peculiar contradictions. It is strange that an artist as committed as Haacke to demystifying notions of purity should have become himself almost a high priest. For his supporters, he is an untainted ideal. Some people approach his work with the kind of hushed awe that the artist finds so questionable in museums.
The timeless dimension of his pieces may also seem surprising for an artist whose work is in some way about ideology and history. But Haacke is oriented by a political perspective or framework that sees itself as in some way primary or original -so absolutely true that it can only be challenged from within. The New Museum has reinforced this myth by producing an exhibition catalogue without a biography and with almost no discussion of artistic development. What it essentially offers is Haacke's catalogue of 17 years of work and sharply focused political discussion.
This is very similar to the treatment that the Museum of Modern Art has given to an altogether different artist, the Formalist painter Morris Louis. Past and personal history was basically unimportant. What mattered most was a particular language that remains absolute for those who believe in it. Together, the two shows suggest one reason why Marxists have been so obsessed with Formalism. The kind of political analysis that has been undertaken with such clarity and commitment by Haacke, and that is being undertaken now by many politically directed art critics and art historians, may be less an alternative to Formalism than the other side of the same coin.
The exhibition was organized by the adjunct curator Brian Wallis. After leaving the New Museum - at 583 Broadway, between Houston and Prince Streets - on Feb. 15, it will travel to the Mendel Art Gallery in Saskatoon, Saskatchewan; the La Jolla (Calif.) Museum of Contemporary Art; the Lowe Art Museum in Coral Gables, Fla., and the Everson Museum of Art in Syracuse. Also of interest this week: Nancy Graves (Knoedler Gallery, 19 East 70th Street): In this show of works on paper, Nancy Graves has something surprising to say. In some works she used gouache, in others pastel. Together they shed new light on an artist who wants her work to be everything, including a dialogue with artists from prehistory to the present.
Throughout the show, the decorative and ritualistic coexist. The ways in which flat, nearly abstract forms dance across paper suggest the pattern paintings of Robert Kushner and Kim McConnel. But the decorative patterns are also filled with traces of signature Graves forms like bones and leaves. And in a work like ''Brewarrina,'' from the ''Australia Series,'' there is a bridge between the kind of jumpy, biomorphic shapes that appear in Matisse's ''Jazz'' and the darting gestures and movements in aboriginal art.
In recent drawings, there is a strong dose of van Gogh, and with it a search for a denser, more concentrated statement. One of Graves's still-lifes seems almost on top of us; the orange in another work suggests the heat of van Gogh's colors at Arles; a blue seems to grope toward the blue of van Gogh at Auvers. The need for a new kind of gravity can also be felt in a recent work that contains a human figure reminiscent of Etruscan tomb painting and a symbolic spherical form that could come out of one of the rawest paintings of Jackson Pollock.
In several works there are isolated images of the human eye. In ''Noonkanbah,'' one frontal eye seems alone, but it is attached to a head that is turned to one side. In Graves's previous works, there was more of a profile approach: more of a sense of continuous movement that went off on its own and was not all that interested in looking at us directly. A will to confrontation is growing. (Through Jan. 3.)
photo of work by Hans Haacke