The idea of getting something for nothing has an ageless appeal to which the District of Columbia government has succumbed in its proposal to barter away two prime blocks of urban real estate in return for a downtown university campus.

The area in question -- four city blocks near the new convention center and directly north of Mount Vernon Square, between 7th and 9th streets and K and M streets NW -- is both big and strategically located. What happens there will have tremendous effect not only upon the residential Shaw neighborhood that surrounds it but also upon the future of the entire downtown area.

On the surface the proposal may look like "one hell of a deal," as D.C. Planning Director James Gibson has said. By allowing a private developer to build a hotel-office complex on two of those blocks the University of the District of Columbia would get -- free -- the classrooms and academic offices on the remaining two blocks of the Mount Vernon site.

However, to treat these huge chunks of cleared urban turf as squares on the game board of downtown redevelopment suggests that the boom-town psychology affecting all of the old downtown east of 15th Street has spread way too far.

The original idea, when the land north of the old public library (now restored) was purchased and cleared, was to reserve the whole site for UDC's central campus. The symbolical and functional appeal of this idea is undebatable. It was possible to envision a campus that served both the educational needs of the institution and that provided a lively focus for the city neighborhood in which it was to sit.

Unfortunately, in a classic maneuver by which an aggressive lieutenant outran the generals, a former chieftain of the Washington Technical Institute, one of the three institutions brought together to form UDC, forged ahead on the construction of a campus on Connecticut Avenue across from Van Ness Center. The big Van Ness campus now serves 70 percent of the university's needs. This, coupled with congressional refusal to fund the downtown campus, explains the city's enthusiasm for its proposed free half-loaf downtown.

Unhappily, this half-loaf promises to be half-baked. As a clever scheme to counteract congressional parsimony, it merits a nod of approval. In these days of zoning incentives and development trade-offs, it has the right ring. But even if it makes a short-term sort of sense, it lacks an essential ingredient: wisdom, an intrinsically long-term quality.

Also, it goes against the sound advice of the District's own long-term planning projections. The general land use guide of the District's Downtown Urban Renewal Plan sets the pattern of reserving the area north of Massachusetts Avenue for residential use. The government's zoning regulations themselves establish that boulevard as the northern boundary of the central business district.

And then there is "A Living Downtown for Washington, D.C.," composed by District planners and published in April, a document studded with references to the importance of housing to a "living" downtown. "District policy is to encourage appropriate residential development along the Massachusetts Avenue corridor," it says on one page. "It is important to achieve a mass of residential units and a physical design and environment which encourages a sense of community," it says on another.

Without such a residential mass, it continues, the area "will not gain the full sense of community that is desired." Elsewhere, it states a key lesson: "Office development must be restricted in areas where housing is desired in order to keep land costs down and so there can be enough units to create neighborhood identity." Concerning the UDC site, this report points out that if the campus plans are scaled back, "the area is ideal for residential development, with nearby food stores and excellent public transportation."

Of course, great obstacles here are market forces that favor office, hotel and commercial development amid federal government policies that restrict low- and medium-income residential building -- two handles of a nutcracker that unquestionably restricts action and, apparently, also imprisons the imagination and vision of the District's top planners.

Even so, as this document implies, the goal is worth the time and risk. "To ensure that non-subsidized units in such a development (on the UDC site) would serve the average downtown worker and not be limited to upper-income households, the land would need to be sold below its fair market value. That would be a public subsidy to the entire project, but it could be justified because of its public benefits."

Common sense supports the wisdom of these "planning concepts." To walk around in the nearby Shaw neighborhood is to witness a scene of poverty and urban waste, but there certainly is plenty of downtown living going on, literally a daily theater of the streets that is full of possibilities for real renewal. Along with the dilapidated (if beautiful) housing there are a number of signs of self-help. In cooperation with the District and federal governments, the churches of the area have constructed new row and high-rise housing. The restored O Street market and the new Giant store, just two blocks north of the UDC site, make up an excellent neighborhood center with great potential.

In effect, the District government is proposing an outrageous expansion of the central business district into an area that is beautifully suited to meet the city's pressing need for close-in housing. The reason such a proposal can even be considered, of course, is the proximity of the convention center, just a block south of Mount Vernon Square.

Still, it is not hard to imagine the deadening impact, socially, racially and architecturally, of the incursion of large-scale office and hotel buildings and their users. The city, of course, should welcome the money and life conventioneers bring to it, but sound planning and common sense demand that these visitors be guided south, into the heart of the old downtown, for places to spend and to be entertained.

Neither is it hard to imagine the kind of buildings that will result. To say that imaginative design is not high on the list of requirements set forth in the government's prospectus for the proposed development is to exaggerrate with understatement. Despite the fact that the architectural challenge is immense and its resolution crucial, design is hardly mentioned in the prospectus and then in a way that guarantees depressing mediocrity.

Concerning the academic mega-building to be located on the eastern portion of the site, the District simply asks that it "shall be sound and substantial and of a type generally recognized as a modern educational building." This statement invites ridicule. Sound and substantial describe engineering necessities, but they also can be interpreted as a prescription for a city fortress. This may indeed be the general preconception of a "modern educational building," a loony, ironic twist due in great measure to governments (D.C. included) that insist on building them that way.

The key word, I suppose, is "modern." Maybe the intention was simply to preclude spires and gothic arches, but in effect it calls for a project that sets itself off from the existing architectural environment. The open-space plan, calling for a 100-foot wide pedestrian mall to bisect the project along the 8th Street axis, is misguided, as well. By forcing building masses towards the outside edges of the site, (along 7th and 9th streets) it severely restricts choices as to how the complex might genuinely open itself to the community.

Time is money in the development business these days, so the District's rush to get this project under way is understandable. So is the university's desire for a downtown campus, despite the fait accompli of a near-complete campus in the wrong location. But the proposal smacks of a quick fix that contradicts or ignores many of the important long-range interests of the city.