Not everybody liked “Slumdog Millionaire” as much as the Oscar committee did. Aside from slum dwellers offended by the title, some critics lambasted its portrait of life in Dharavi, the biggest slum in Mumbai, as exploitative. A Times of London columnist dubbed it “poverty porn” for inviting viewers to gawk at the squalor and violence of its setting.

But according to a less widely noticed perspective, the problem is not just voyeurism; it’s the limited conception of slums, in that movie and in the public mind. No one denies that slums – also known as shantytowns, squatter cities, and informal settlements – have serious problems. They are as a rule overcrowded, unhealthy, and emblems of profound inequality. But among architects, planners, and other thinkers, there is a growing realization that they also possess unique strengths, and may even hold lessons in successful urban development.

The appreciation can come from unlikely quarters: In a recent speech, Prince Charles of England, who founded an organization called the Foundation for the Built Environment, praised Dharavi (which he visited in 2003) for its “underlying, intuitive ‘grammar of design’ ” and “the timeless quality and resilience of vernacular settlements.” He predicted that “in a few years’ time such communities will be perceived as best equipped to face the challenges that confront us because they have built-in resilience and genuinely durable ways of living.”

He echoes development specialists and slum dwellers themselves in arguing that slums have assets along with their obvious shortcomings. Their humming economic activity and proximity to city centers represent big advantages over the subsistence farming that many slum dwellers have fled. Numerous observers have noted the enterprising spirit of these places, evident not only in their countless tiny businesses, but also in the constant upgrading and expansion of homes. Longstanding slum communities tend to be much more tightknit than many prosperous parts of the developed world, where neighbors hardly know one another. Indeed, slums embody many of the principles frequently invoked by urban planners: They are walkable, high-density, and mixed-use, meaning that housing and commerce mingle. Consider too that the buildings are often made of materials that would otherwise be piling up in landfills, and slums are by some measures exceptionally ecologically friendly. Some countries have begun trying to mitigate the problems with slums rather than eliminate the slums themselves. Cable cars are being installed as transit in a few Latin American shantytowns, and some municipal governments have struck arrangements with squatters to connect them with electricity and sanitation services.

And there are thinkers who take the idea a step further, arguing that slums should prompt the rest of us to reconsider our own cities. While the idea of emulating slums may seem absurd, a number of planners and environmentalists say that we would do well to incorporate their promising elements. One architect, Teddy Cruz, has taken the shantytowns of Tijuana as inspiration for his own designs; he is currently working on a development in Hudson, N.Y., that draws on their organically formed density.

“We should not dismiss them because they look ugly, they look messy,” says Cruz, a professor at UC San Diego. “They have sophisticated, participatory practices, a light way of occupying the land. Because people are trying to survive, creativity flourishes.”

To be sure, there is something unseemly in privileged people rhapsodizing about such places. Prince Charles, for all his praise, does not appear poised to move to a shack in Dharavi. Identifying the positive aspects of poverty risks glorifying it or rationalizing it. Moreover, some of the qualities extolled by analysts are direct results of deprivation. Low resource consumption may be good for the earth, but it is not the residents’ choice. Most proponents of this thinking agree that it’s crucial to address the conflict between improving standards of living and preserving the benefits of shantytowns.

But given the reality that poverty exists and seems unlikely to disappear soon, squatter cities can also be seen as a remarkably successful response to adversity – more successful, in fact, than the alternatives governments have tried to devise over the years. They also represent the future. An estimated 1 billion people now live in them, a number that is projected to double by 2030. The global urban population recently exceeded the rural for the first time, and the majority of that growth has occurred in slums. According to Stewart Brand, founder of the Long Now Foundation and author of the forthcoming book “Whole Earth Discipline,” which covers these issues, “It’s a clear-eyed, direct view we’re calling for – neither romanticizing squatter cities or regarding them as a pestilence. These things are more solution than problem.”

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The word “slum” itself is controversial and slippery. In the United States, it is often used to refer simply to marginalized neighborhoods, but in developing countries, it usually means a settlement built in or near a city by the residents themselves, without official authorization or regulation. Housing is typically substandard, and the infrastructure and services range from nonexistent to improvised.

There is nearly as much diversity among informal settlements (a term sometimes used in preference to the more loaded “slum”) as in their formal counterparts. They include a wide range of economic levels and precariousness. In Kenya, about a million people live in Kibera, outside the city center of Nairobi. Its huts are built of mud and corrugated metal, trash is everywhere underfoot, and “flying toilets” – plastic bags used for defecation and then tossed – substitute for a sanitation system. In Istanbul, by contrast, where the city government has been more sympathetic, some squatter areas have water piped into every home.

Without some degree of government support, slums tend to be fetid and disease-ridden, and until a few decades ago, the most popular approach to solving their problems was to demolish them. In the 1960s and 1970s, Brazil, for example, razed many of its slums, called favelas, and relocated residents to government housing. But since then, a new idea has emerged in development circles: that such settlements are more than eyesores; they are the product of years of residents’ labor, and legitimate communities that should be improved rather than erased.

“One of the misconceptions is that they’re endless seas of mud huts,” says Robert Neuwirth, author of “Shadow Cities: a Billion Squatters, a New Urban World,” who spent two years living in squatter communities. “There’s a tremendous amount of economic activity – stores, bars, hairdressers, everything.”

An early reappraisal came in the book “Freedom to Build: Dweller Control of the Housing Process” (1972), edited by John F. C. Turner and Robert Fichter. Some of the contributors had closely studied squatter communities in the developing world, and the book argued that when people had autonomy over their housing and their environments, the residents and the settlements thrived. The development community began to recognize the drawbacks of evicting people and relocating them, which can be “incredibly traumatic,” says Diana Mitlin, senior research associate at the International Institute for Environment and Development in the UK. In 1975, the World Bank officially changed its position to endorse upgrading instead of new site development for squatters.

More recently, shantytowns have been reassessed in light of the growing awareness of the benefits of urbanization. Cities provide myriad economic opportunities that are lacking in the countryside, which is why millions of people stream in every month. They also offer freedom – especially, notes Brand, for women, who find greater access to jobs and education, as well as healthcare. Birthrates tend to fall when families move from villages to cities, not only thanks to family planning services, but also because more children, an asset on the farm, are a burden in the city.

What’s more, cities are increasingly seen as good for the planet. Aside from slowing population growth, they’re also more efficient in their use of resources, and allow abandoned land in the country to regenerate.

Most of these benefits, of course, would accrue even if migrants were moving to apartments in fashionable districts. But in practice, urbanization means the movement of poor people into slums. And while this reality certainly poses challenges, in the past few years, some analysts have begun to see slums as not simply the only realistic option, but as having certain advantages over formal settlements, especially the government-built high-rise projects where the poor are often housed.

Shantytowns are “pedestrian-friendly. There are small alleyways, the streets are narrow. Children can play in the streets,” says Christian Werthmann, a professor of landscape architecture at Harvard. Some frustrating parts of slum life – the close quarters and the need to cooperate with neighbors in endeavors like obtaining services – have an upside: they can contribute to a strong sense of community. And although many shantytowns are dangerous, some actually have very low crime rates. Writing recently in the New York Times, two researchers affiliated with the Indian nonprofit Partners for Urban Knowledge Action and Research defended the highly developed slum of Dharavi as “perhaps safer than most American cities,” protected by the watchful eyes of close-knit neighbors.

There is an ethos of self-reliance in communities independently built and continually rebuilt by their residents. Over the course of years or decades, residents may upgrade from cardboard to corrugated metal to brick, add floors on top of the roof. They are invested in their creations, and typically prefer them to the feasible alternatives. “When people are relocated to places where government thinks they can be housed in a better way, they often move back,” says Hank Dittmar, chief executive of Prince Charles’s Foundation for the Built Environment. Living in a legal neighborhood would usually mean more money for less space, without the prospect of improving or expanding. And it might entail constraints that don’t apply in the slums – for instance, zoning laws about where it’s acceptable to operate businesses.

Another major concern of contemporary urban planners is ecological sustainability, and shantytowns get high marks for that, too. Teddy Cruz, who has spent a great deal of time in Tijuana, says, “These slums have been made with the waste of San Diego. . . . Aluminum windows, garage doors. Debris is building these slums.”

Still, most shantytowns remain difficult and unhealthy places for people to live and grow up. They are also reviled by their wealthier neighbors, and as cities expand, sometimes they find themselves in the crosshairs of developers eager to build on their prime real estate. Some countries continue to clear slums: In 2005, Zimbabwe perpetrated brutal demolitions, called Operation Drive Out Trash, which left hundreds of thousands of settlers homeless. Dharavi is located in the heart of Mumbai, and plans have been underway to develop high-rises and high-end commercial ventures in that area. Following protests, the plans will now be reviewed by an advisory group that includes some residents.

In a number of countries, government and aid organizations have been working with squatters to retrofit slums. Brazilian favela dwellers, who are voters, have obtained concessions such as hookups to water mains and electricity. Squatters in many cities have established their own activist organizations, which work together under an umbrella group called Shack/Slum Dwellers International. Jockin Arputham, the group’s president (and head of India’s national slum-dweller organization) recalled in a published interview that years ago he led a large group of children in collecting garbage in their community and depositing it in front of the municipal council’s offices. “[W]e showed them the garbage problem in our settlement and began a negotiation,” he told the journal Environment & Urbanization. “We said that we would organize the garbage collection if the municipality would provide the truck to collect it regularly.” The gambit worked.

There is debate about whether the informality itself is a plus or a minus. Hernando de Soto, a Peruvian economist, has argued that slum dwellers should be given title deeds for their plots, in order to liberate the “dead capital” they are sitting on – to enable them to get loans from banks. But many analysts are skeptical of this proposal. One problem is that individual property rights could disrupt the stable system of communal control that has evolved in many slums. Another possibility is that residents might quickly sell their new deeds for cash, and thus lose the rights to their longtime homes.