To passersby, it is a jumble of tents and blue tarps, the iconic symbol of the displaced, the temporary, the makeshift. Set against the orderly but dull architectural backdrop of McPherson Square, the Occupy D.C. encampment is a low-slung and seemingly haphazard arrangement. But it has made this sleepy public space, used mainly by office workers and a few residents of nearby luxury condominiums, one of the busiest public squares in Washington. To use the argot of urbanism, the protesters who installed themselves at McPherson Square on Oct. 1 (and another group that has occupied Freedom Plaza a few blocks away) have done what so many planners, designers and architects strive for but fail to achieve: They have “activated” the urban core.

Whether the Occupy movement, which has taken over parks in cities across the country, fizzles or grows, whether it has resonance and can translate its message into concrete change, are political questions. But looked at solely as an aesthetic and cultural phenomenon, it has deep roots in ideas with established pedigrees in the world of art and architecture. Its anti-consumerist ethos, its impatience with the media and its love of theatrical intervention in city life make it a direct heir of the Situationists, a radical European avant-garde collective begun in the late 1950s with ideas that remain influential today.

It might also be considered a living exercise in do-it-yourself (or DIY) urbanism, a trendy movement that strives to engage ordinary people in a hands-on approach to shaping and claiming public space.

And it seems a perfect fit with an exhibition, “The Interventionists,” which opened at the Massachusetts Museum of Contemporary Art in 2004. The show surveyed artists and activist groups that sought to “disrupt daily life” in creative ways, challenging the control and design of urban space. It included guerrilla groups such as the Biotic Baking Brigade — famous for throwing a pie at Bill Gates — which “believes that under neoliberalism, we can all throw a pie in the face of economic fascism,” and the video work of artist Alex Villar, who films people occupying urban space in odd and unconventional ways.

An eye for symbolism

Although Occupy D.C. eschews formal leadership and has been criticized for its amorphous organization and goals, it has proved remarkably adept at symbolism, especially urban symbolism. Charlie Hailey, author of the 2009 survey “Camps: A Guide to 21st Century Space,” an extensive taxonomy and analysis of temporary forms of urbanism, sees parallels between the Occupy movement and the tradition of long-standing protest camps in Europe, especially Britain, where a pacifist group created the Greenham Common Women’s Peace Camp, which stood outside an air base for 19 years until it disbanded in 2000. He’s struck by McPherson Square’s significance as a protest site.

“It is about legibility,” he says of the site’s proximity to the White House and the lobbyist corridor of K Street NW. “The adjacency is really striking.”

Hailey’s book surveys the history and the symbolism of camps, from recreational camping to refugee and displaced-persons camps. The visual power of the occupied McPherson Square recalls the childhood emotional associations of backyard camping as much as the insecurity and fear associated with the blue tarps that became ubiquitous after Hurricane Katrina. It is also a relatively rare American encounter with squatting, a phenomenon that has defined, energized and irritated some of Europe’s most creative cities, including Berlin. While to some the camp may look like a pragmatic solution to a basic problem — how to shelter a group that seeks impact by drawing out over time a small protest, rather than organizing a massive, one-day march on the Mall — it’s also a study in self-expression.

“There is a self-consciousness to camping,” says Hailey. “It is a truly applied aesthetics.”

That self-expression makes McPherson Square a dynamic study in improvisation and adaptation. Signage, made mostly with recycled cardboard and pizza boxes, is everywhere, creating a cacophony of anti-capitalist messages that resists the bullet-point thinking of commercial and organizational culture. Practical adaptations to living outdoors take on artistic resonance. To make it easier to fill water jugs, someone has created an elegant system of two bamboo sluices that channel water from a drinking fountain. No one would take credit for this small “hack” of standard urban furniture. But that refusal of authorship is also part of the Occupy value system.

The complexity of the movement’s motivations and goals is also seen in its paradoxically conservative use of space. Without creating formal rules, the occupiers have essentially “zoned” the park into residential and public spaces. In the northwest corner, tents for a kitchen, an information booth and a planned falafel shop are kept separate from the living areas. A large field in the southwest quadrant has been left open for public meetings and sport and to accommodate a brace of ducks that are also resident in the park.

“After that, it’s open to all,” said Anthony Sluder, when asked if anyone can pitch a tent anywhere. Sluder, who was manning the information tent, said newcomers were welcome to “any space your neighbors don’t care about.”

Imagining a city on the fly

The idea that people, working through consensus, can solve basic problems such as how to regulate public space, security and infrastructure is one of the most powerful spurs to current architectural thinking. Younger architects and planners are studying how people actually use space rather than adopting top-down design ideas fashioned by governments or urban theorists. A new sense of post-Utopian architecture is replacing older, modernist efforts to impose ideal order on the in­trac­table city. After analyzing how people in Rio de Janeiro’s largest favela, or shanty town, respond to their harsh urban environment, the architects at Atelier UM+D (based in southern Brazil) proposed designs for an innovative skyscraper that would blur the lines between public and private space, organize residents around basic needs such as food and medical care, and allow for far greater adaptability than most carefully programmed urban buildings.

“We don’t think there should be a massive plan that would solve all their problems,” said one of the firm’s architects, who asked not to be quoted by name because it is a collective project. “It should always be changing, always intertwined and interconnected with the needs of the people, and those needs always change. The scale of the decision should be somewhat smaller.”

That is, in effect, also the message not just of many of the Occupy protesters but also of many in the right-wing tea party movement: Give us a more direct and more responsive democracy. And both movements share a taste for nostalgia, whether it’s Norman Rockwell visions of the small-town meeting or echoes of 1960s protests in song and dress. But the choice of the urban camp as its primary symbol connects the Occupy movement to efforts to reformulate the definition of the city, going all the way back to the designs of the radical architectural collective Archigram, which envisioned temporary cities and ephemeral landscapes in the 1960s and ’70s. An afternoon walk through the occupied McPherson Square, where pup tents and computers define an urban aesthetic that is strong on connectivity and loose on formal organization, is reminiscent of one of Archigram’s more poetic fantasies. “I like to think,” wrote one Archigram visionary in language curiously reminiscent of the poetic idealism of many Occupy residents, “of a cybernetic forest filled with pines and electronica where deer stroll peacefully past computers as if they were flowers with spinning blossoms.”

In Washington, the contrast between the planned, commercialized urbanism of areas such as Seventh Street NW and the unplanned but spontaneous and temporary urbanism of McPherson Square seems ready-made to illustrate a basic argument of the Situationists: That capitalism uses spectacle to control and degrade culture.

On Seventh Street, giant video screens, enormous electronic signs and an alluring blur of brand-name restaurants and stores mask the generic commercialization of what could have been, with the Shakespeare Theatre and the old Carnegie Library, a major cultural artery. In McPherson Square, the Occupy protesters have created a spontaneous library and host musical performances, all without major corporate sponsorship.

Hints of the ‘urban uncanny’

But the Occupy movement has also brought into the heart of the nation’s capital something even more haunting, what might be called the “urban uncanny.” Some of the most cherished cities in the world, including Vienna, owe their early development in part to the encampments set up by occupying Roman soldiers. Other major metropolitan areas, such as Port-au-Prince and New Orleans, devolved more or less into camps after disasters struck. The urban encampment hints at the beginning and the end of urban life, its nascence and dissolution. It’s a powerful display, a mix of both admonition and promise, suggesting not only that we could all be homeless but that we could also live better, differently, more communally.

Pundits will debate the ultimate political impact of the Occupy movement. Its cultural impact will depend on whether mainstream arts and design organizations are flexible enough to take note of something new in their midst.

“Where are the universities, the academics, what is the A.I.A. doing?” asks Richard Koshalek, director of the Smithsonian’s Hirshhorn Museum. The A.I.A. is the American Institute of Architects, one of many professional groups that might learn a lot from the Occupy movement.

The possibilities for fruitful dialogue are already apparent in a project Koshalek has planned for the Hirshhorn. If everything goes right, the museum will inflate a giant “bubble” made of plastic inside its circular courtyard sometime in 2013. Designed by the cutting-edge architectural firm Diller Scofidio + Renfro, which has pioneered ideas for ephemeral and temporary architecture (including a pavilion made of water vapor created for a Swiss exposition in 2002), the Hirshhorn bubble will be a kind of intellectual camp, a seasonal, flexible space designed to tap into many of the same energies that are flowing in what has become Washington’s most vibrant public square.