Because it is so fortunate in superb older examples of the process, and so lacking in distinguished newer ones, Washington is a good place to consider the issues raised by "Collaboration: Artists and Architects," a touring exhibition that opened yesterday at the Corcoran Gallery of Art.

Although it contains one stunning model of the magic that can happen when architect and artist work sensitively together--a simple, free-standing hexagonal room created by Cesar Pelli to harbor paintings by William Bailey--the exhibition is less important for what it practices than what it preaches.

Organized last year by the Architecture League of New York on the occasion of its 100th anniversary, the show advances the idea that the time has come at last to reestablish ancient bonds between the visual arts that have been more or less systematically severed in our century.

This is, of course, a lot easier to say than to do, as the exhibit's mixed results attest yet again. The problems are manifold.

The creators of modern architecture, whatever their other significant differences, spoke as one against architectural ornament as part of a general attack upon traditional cultural forms and rules. Although in theory this did not prohibit cooperation between different artistic disciplines, in practice it seriously circumscribed opportunities for sculptors and painters to participate meaningfully in the architectural enterprise. Modern architecture set itself up as the one art above all others; its masterpieces aspire to, and often attain, an all-embracing sort of esthetic self-sufficiency.

Parallel impulses persuaded many modern artists to abandon the old idea of collaboration. In the prototypical examples of El Lissitzky and Kurt Schwitters, for instance, art aspired to the condition of architecture, while many more modern artists preferred, as a matter of honor and/or self-identity, to go it alone against the world.

Then, too, the economics of contemporary building continue to mitigate against genuine collaboration. Real estate speculation is the engine that runs most building projects these days, so it is legitimate to ask, what is the point of art in a time of planned obsolescence? It is difficult to design well under such circumstances, and far more vexing to make art.

Even many of the solutions advanced by the growing list of government and corporate sponsors of "public art" and "art-in-architecture" programs, at least until recently, have failed to address the problem head-on. Sometimes such commissions work beautifully; more often they fall flat. Almost always, they involve art as a relatively last-minute embellishment.

To address these questions and a host of others was the idea behind the "Collaboration" exhibit, in which 11 leading architects were asked to select compatible artists and then to work with them under a flexible charge to create something "between the visionary and the pragmatic, or at least remotely possible."

Although the results are not uninteresting, the show's main contribution may be to send the viewer out into the city again with a fresh eye. The evidence is overwhelming: Much that is beautiful in Washington is due to an inspired level of collaboration between architects and artists.

Very little of this evidence, it must be said, is of recent vintage. In fact, the occasions of superior contemporary artwork in our city setting can be counted on a few fingers.

The best correspondence between the place and modern art was, alas, nothing more than an inspired accident: In the late 1960s the painter Barnett Newman was persuaded to lend his impressive sculpture, "Broken Obelisk," to the Corcoran, where it was installed outside at the corner of New York Avenue and 17th Street NW. It didn't last long (Newman withdrew the piece when his friend, the Corcoran director, was fired), but what a triumph it was.

Somehow Newman's large bronze piece, an obelisk turned on end and balanced precariously atop a massive pyramid, looked as if had been placed near the rounded corner of Ernest Flagg's Beaux-Arts Corcoran building from the day it opened, and the sculpture played a constantly changing game of hide-and-seek with the other obelisk in town, the Washington monument.

Then there is Tony Smith's adamant construction in blue-painted steel hidden away in a courtyard of the Labor Department building, and Ed McGowin's stealthy steel box up on 19th Street NW, its tiny windows offering a glimpse of the still life inside, and that's it. Everything else even remotely contemporary in style has the look of that James Rosati sculpture in front of the Marcel Breuer HEW building--elegant and forlorn.

The scale, classic revival ambience and bureaucratic inertia of the city clearly has discouraged contemporary collaborative experiment here, but it hasn't always been so. In ways both minor and major the city is replete with magnificent examples: A.P. Proctor's great bronze buffaloes flanking the impressive bridge (Glenn and Bedford Brown, designers) at 23rd and Q streets NW; Henry Bacon's marvelous park, Dupont Circle, unthinkable without the grace note of Daniel Chester French's fountain; Smithmeyer and Pelz's Library of Congress, a full-blown opera of art in architecture . . . the list could go on until tomorrow.

The Mall itself, of course, is the city's greatest collaborative effort, from the Capitol to Henry Shrady's tremendous equestrian statue of Grant to the Washington Monument to the Lincoln Memorial (where Bacon and French triumphed again)--the country's most moving spatial ensemble. One of the lessons of this great space is that the contributions of strong-willed creative individuals are not wasted when they operate within the bounds of an impressive overall idea and a time-honored stylistic consensus. Whether this is a lesson for today is an arguable point.

At the very least it should be pointed out that one contemporary artist--Rockne Krebs with his breathtaking laser structures originating at the Lincoln and Jefferson Memorials--devised a brilliant contemporary way to do justice to the timeless ambience of the space. So, it can be done, and it is not at all surprising to find several of the more successful collaborators in the show at the Corcoran--Robert Stern and sculptor Robert Graham, Michael Graves and Lennart Anderson--looking back in time both for stylistic clues and standards of civility applicable to the present.

Another pair, Emilio Ambasz and painter Michael Meritet, took a more poetic, environmental, universal overview of the challenge in their proposal for tree-lined city gates, while others, such as Richard Meier and Frank Stella, proved that it can be done, and done well, within the confines of modernist esthetics.

Still, for a timeless demonstration of the careful calibration of vision, energy and skill necessary in any successful collaborative enterprise, the little house that Pelli built for Bailey's paintings cannot be topped. Everything about the space enhances the solemn mood of the paintings, and the paintings complement the subtleties of the space: a perfect, if modest, union, and not a bad place to begin again.

The exhibition, organized for the Architecture League by Barbaralee Diamonstein and supported by grants from Philip Morris Inc., the National Endowment for the Arts and the New York State Council on the Arts, will remain at the Corcoran through Aug. 13.