Times Square is perched on the brink of major change and, not surprisingly, New Yorkers are furiously debating its future. The questions of how many and what kinds of changes can be made without fundamentally altering the special character of one of the world's best-known places are everywhere being asked.

What gives the debate its urgency is the timetable. On Thursday the state's powerful Urban Development Corp. voted in favor of a plan to resurrect five legitimate theaters and transform four others, and to build four new office buildings totaling nearly 4.1 million square feet, a 2.4-million-square-foot wholesale merchandise mart and a hotel of up to 750 rooms in an area bordered by Broadway and Eighth Avenue on the east and west, and 43rd and 41st streets on the north and south. A favorable vote by the city's Board of Estimate on Oct. 25 would clear the way for the massive development to begin.

What gives the debate its piquancy is that many of the plan's sharpest critics were once its most persuasive supporters. A carefully wrought alliance among the city, the state and interested private groups (including nearby neighborhood associations, garment industry representatives, pro-theater groups and an assortment of strong-minded design and planning associations) is unraveling day by day. As a result, an attempt, exemplary in many ways, to assure continuity and excellence in architecture through strong design controls is in danger of being severely distorted.

The four giant office towers designed by John Burgee and Philip Johnson so far have been the focal point of the controversy. With their simplified profiles and exaggerated historical quotations (from high granite bases to superscale mansard tops), the buildings are typical of the Burgee-Johnson team and are handsome structures in their own right. But they clearly would change forever both the image and the reality of Times Square.

At this point it's hard to tell what will happen. By conservative estimate, the whole Times Square project would take nearly a decade to build. Perhaps sensing defeat on the design issues, opponents recently have focused more attention on procedures. They fear that in the absence of strong follow-through and binding legal agreements, the theaters could be gobbled up by development. "It is supposed to be a quid pro quo arrangement," commented George Lewis, executive director of the New York City chapter of the American Institute of Architects, "but at this point the quid is all in place and the quo, which is the theaters, is not."

Huge, government-guided changes at Times Square and along 42nd Street have been contemplated for years, but very little has been accomplished. The goals, however, have remained pretty much the same: to "clean up" the sleazy, and dangerous, rows of pornographic stores and movie houses that have all but taken over this portion of 42nd Street in the past two decades; to shift some office development westward from the overbuilt East Side of midtown Manhattan; to restore legitimate theater to its former proud position in the area and to upgrade one of the biggest underground transportation connections in the world; and to preserve, in the words of the latest plan, the "excitement and energy of 42nd Street . . . the uninhibited, flamboyant character of its illuminated signs, billboards, marquees . . ."

The fact that these goals are somewhat contradictory is the source of much of today's conflict. But the reality driving enlightened planners to dream such dreams was that, in time, the demand for offices and hotels in midtown would push development westward anyway. Besides putting even more pressure on surviving legitimate theaters, this process would without question diminish and possibly destroy the glitter that makes the Times Square intersection of Seventh Avenue and Broadway unique.

(Indeed, the process already has begun. The Marriott Marquis Hotel under construction on Seventh Avenue between 44th and 45th streets, designed by John Portman, is a concrete-and-glass behemoth that overlooks the Great White Way like an invader from another world.)

In any case, the ambitious goals for the area sat on the shelf until 1980, when the city invited the Urban Development Corp. to enter the fray. The UDC, a can-do agency with extraordinary powers (including eminent domain, design controls and fast-track regulatory approvals), devised an audacious, straightforward strategy: concentrate heavy new development at the edges of the area, with office skyscrapers on the east at Times Square and the merchandise mart and hotel on the west at Eighth Avenue, and preserve the low-rise character of the 42nd Street corridor in between. The density bonuses granted to developers on the edges, high even by New York standards, would, in theory, provide much of the money needed to restore and revive the theaters in the middle.

At about the same time, the UDC had taken over the development program for Battery Park City, another long-floundering planners' dream in which an enormous commercial-residential center was to rise upon 92 acres of state-owned landfill in the Hudson River at the southern end of Manhattan. As a builder of well-designed subsidized housing throughout New York State, UDC had compiled an outstanding record in the early 1970s. By 1980, explained its then-head Richard Kahan, the situation had changed drastically. "It was a different era of public development," he recalled. "After the financial crisis of the mid-'70s, the idea of large state payments was no longer valid. Our concept became one of true joint-venture development with private capital."

Battery Park City, an amazing story in itself, is off to a great start. But Alexander Cooper, a partner in the architectural firm (Cooper, Eckstut Associates) that drew up the design guidelines for both projects, points out a tremendous difference between the two: At Times Square the state did not own the land, and didn't have the money to buy it. "So it's a shell game, a great flashing of mirrors," Cooper said, "because the public sector brings nothing to the table."

Nothing, that is, but the exceptional powers of the UDC, which can, and did, reshape customary zoning patterns to fit its strategy of concentrating development at the edges of the area. ("That is where the site can take it," Cooper observed.) In this game the main mirrors being flashed were the design guidelines Cooper helped to write, which met with almost universal applause when first published in the spring of 1981. "The guidelines impose requirements where they are deemed necessary to achieve the stated objectives," that document states. "These requirements are not discretionary, and proposals must conform to them to be considered."

Whether the guidelines are too specific is a matter of debate. In addition to height limitations, setback requirements, usage controls, ground-floor entrance and exit regulations and many other rules governing the relationships between buildings, they go far toward establishing an architectural style. They require a "two-dimensional" skin of metal and/or glass for the new buildings, which are to be "transparent at the bottom" (where the stores are), "reflective at the top," brightly lit and covered, wherever possible, with signs -- a cross, sort of, between Art Deco and contemporary high-tech design.

The spirit of the guidelines, however, is clear. With their emphasis on lighting, signs and ground-floor retail-restaurant uses, and zippy set-back building profiles, they were to be the primary mechanism for maintaining the visual character of the Times Square-42nd Street area. This, obviously, is the most difficult of all of the project's goals -- how does one preserve the ambiance of a place while subjecting it to great changes in scale and use? -- and it is the basis upon which the Burgee-Johnson designs have been attacked almost since the day they were unveiled last December.

True, the architects have altered their designs somewhat since then. Originally, they proposed demolishing the Times Tower (the building the New Year's Eve ball drops from), but they have devised a scheme to save it by stripping it of its ugly 1960s marble skin and decorating the exposed steel frame with high-powered signs and lights. (Ironically, this proposal is not unlike several entries in a recent Times Tower international design competition sponsored by the Municipal Art Society of New York and the National Endowment for the Arts.) And they have increased the amount of signage and lighting on the lower floors. But the changes don't really fit the design very well -- the office towers retain their awesomely corporate character.

The architects make no bones at all about their intention, in Burgee's words, "to give Times Square a much greater sense of place." They mention Rockefeller Center in New York, or the Royal Crescent at Bath, or the Rue de Rivoli and the Place Vendo me in Paris -- great places all. But none is anything like Times Square, which in no way is a classically defined urban space. When standing in that "square," simultaneously observing the nighttime spectacle of the great signs and trying to substitute the Burgee-Johnson vision, one would have to be hard-hearted or blind, or both, not to feel a sense of loss.

Next week: Battery Park City.