It is because every individual knows little and, in particular, because we rarely know which of us knows best that we trust the independent and competitive efforts of many to induce the emergence of what we shall want when we see it. — Friedrich Hayek, The Constitution of Liberty

Imagine the perfect city. If you have a clear picture in mind, you’re not alone. Tsars, emperors, and prophets have been trying to build perfect cities for millennia. With the emergence of the field of urban planning and modern social science, everyone from stenographers to industrialists to independent architects have joined in. For Ebenezer Howard, the perfect city was the Garden City, a corporate-owned residential satellite on the outer edge of town. For Le Corbusier, it was the Ville Radieuse, full of “skyscrapers in the park” and elevated highways. For Frank Lloyd Wright, it was Broadacre City, a dispersed anti-city full of single-family homes on one-acre lots. Each reflects a distinct vision of urban life, and each seems to have as many opponents as it does proponents.

Thankfully, few of these plans have ever been implemented in full on a mass scale. Yet “perfect city” thinking—the view that one particular vision of urban form should be imposed by planners—has manifested itself in small ways in cities around the world through the construction and enforcement of specific theories of how a city should work. This approach to urban form involves expanding urban planning beyond prudentially managing infrastructure and mitigating destructive negative externalities and toward enforcing and preserving particular lifestyle and aesthetic preferences. Consider: while Ville Radieuse was never built, many cities bulldozed traditional urban neighborhoods to construct the urban elevated highways of Le Corbusier’s dreams. While Broadacre City never moved beyond the model stage, many suburban communities still zone minimum lot sizes of one acre and heavily restrict apartments, a reflection of Wright’s peculiar view of the ideal urban life. Thinking that one plan can be imposed on the millions of plans developed by residents lives with us today in every Euclidian zoning ordinance and every urban freeway.

What we need is not a new and improved vision of urban form but a robust liberal understanding of urban form. This transition involves shifting from thinking of cities as simple machines toward thinking of cities as complex, emergent systems that evolve through decentralized trial-and-error and reflect the diverse normative preferences of urban residents. This approach incorporates the recognition of three elements: First, given that cities are complex and unpredictable systems, we should resist the urge to heavily centralize their management. Second, in order to function and evolve, cities need relatively free and open land markets and a functioning ecosystem of small developers and entrepreneurs. Third, we must recognize that even if we had all the relevant information about how to manage any given city, the remarkable variety of unique preferences among urban residents should make us wary of strictly regulating urban form and design.

First, a liberal approach to urban form recognizes that cities are complex, emergent systems of which we know very little about at any given moment. As contemporary urban theorist Alain Bertaud argues, even if we break down urban form to a relatively simple equation incorporating land consumption and commuting time and cost, numerous unpredictable exogenous variables still do the heavy lifting in determining the shape of cities. While planners may set floor area ratios (FAR) or assign use zones and assume that they are driving the shape of development, the actual production of a given FAR or mixture of uses is a function of variables like resident incomes, land values, and construction costs. What is and isn’t built is not the prerogative of planners, but the result of a dynamic market process constantly adjusting to the needs and preferences of urban residents and businesses.

Regulating such a system requires humility, as interventions in complex systems can often have far-reaching unintended consequences. As Bertaud points out, simple restrictions on urban development can dramatically reduce the ability of cities to evolve. Around the globe, seemingly innocuous design rules on use segregation and density restrictions have accumulated such that the ability of cities to organically adjust to change is greatly diminished, leaving urban residents worse off. For a dramatic example, Bertaud points to a pseudo-scientific policy in China that mandated that every apartment unit receive a minimum amount of sunlight, forcing development in cities across the country to take the form of dull, uniform, low-density garden apartments. For an equally dramatic example close to home, consider the displacement caused in part by arbitrary restrictions on urban housing in cities like San Francisco and London. While these design restrictions may vary superficially, their effect is the same: by imposing one particular vision of urban form, cities are less able to adapt to changing demand for housing, lifestyle preferences, and economic circumstances.

Second, a liberal approach to urban form recognizes the importance of decentralized actors in driving urban form. Consider: we used to think of the economy the way we think of cities today. For decades, many leading economists argued that, with the right mix of experts and technology, even a system as complex as the economy could be heavily managed. From our privileged position in 2017—well beyond the rise and fall of the planned economies of the right and left—it is easy to see the flaws in this thinking. Yet in the 1930s and 1940s, the thinkers of the beleaguered Austrian School of economics stood in opposition to the “common sense” of the day. The heart of their critique of top-down economic management is best captured in an essay by Friedrich Hayek: given that so much essential information related to economic conditions is distributed among the millions of individual participants in the economy, so must decision making be distributed, with emergent institutions and signals like prices helping to coordinate individual plans in a constantly changing cooperative system we simplistically call “the economy.” As Hayek urged us to take seriously the importance of local knowledge and emergent orders, so his intellectual heir Israel Kirzner urged us to reconsider the importance of the entrepreneur: rather than a marginal opportunist, the entrepreneur is an essential agent of discovery, responding to new conditions with new economic arrangements, succeeding or failing based on her ability to fill a need, inviting others to follow in the process.

In the realm of urban form, we already have such entrepreneurs: developers. Their task is, in simple terms, to coordinate capital, land, and labor in order to reshape the urban form to meet changing needs. Developers survive and thrive based on their ability to experiment with new urban arrangements based on their assessment of current needs. For this reason, successful development firms, large and small, often possess a remarkable degree of local knowledge about their neighborhoods and cities as well as sophisticated data on land and labor markets. Yet even in the relatively innocuous project of building what already works, developers are subject to a byzantine system of permitting fees, site reviews, and public hearings. As the economist Diana Thomas has pointed out, such systems run the risk of crushing the small—innovative—firms while protecting and rewarding the large—conservative—firms and projects, particularly those large developers who are adept at manipulating urban politics. If you remain skeptical of entrepreneurial innovation in urban form—how much innovation can there by in urban real estate, really?—consider this: within the last decade alone, cities across the country restricted novel arrangements like micro apartments, tiny homes, and coworking spaces. Elsewhere, cities fight the revival of pre-planning features of urban form like accessory dwelling units and mixed-use developments. A liberal approach recognizes the role of developers and entrepreneurs as an essential decentralized source of urban innovation and aims to expand their ability to experiment with innovative solutions to changing conditions.

Finally, a liberal approach to urban form accepts that reasonable people can disagree over the ideal urban arrangement. Wrapped into every grand vision and design regulation are particular normative preferences that many may not share. Should retail and residential be separate? Should every apartment receive at least one hour of direct sunlight? Should everyone live on a one acre lot? These are issues on which similarly situated people can reasonably disagree, but in many cities, one particular preference is imposed by force of law. In this regard, our current approach to cities is straightforwardly illiberal. Thanks to the flowering of our contemporary open society, legislating personal preferences has largely disappeared from nearly every other aspect of our lives—art, religion, family arrangements, etc.—yet such habits conspicuously remain in the realm of urban form.

Peruse the urban planning literature, and one finds passionate arguments for mandating this level of density, or restricting this or that mixture of uses. As some groups call for minimum levels of this and maximum amounts of that, others call for maximum levels of this and minimum amounts of that. As some call for maintaining the status quo of suburban zoning, others call for a hard shift toward requiring traditional neighborhood development. This leaves the liberal urbanist in an uncomfortable position: “why not let individuals and groups arrange their communities as they like?” she asks. It’s a position that wins few friends, but a position that calls back to the civilizing core of liberalism. A liberal approach to urban form holds that, without design-based restrictions and subsidies, a variety of urban living arrangements can peacefully coexist.

At first blush, the liberal approach to urban form may seem like a negative stance. Indeed, the liberal approach calls for an end to much of the conventional urban planning regime in place in many cities today. Yet in an important sense, the liberal approach is liberatory, recalling the great virtues of urban life. Jane Jacobs starts The Death and Life of Great American Cities with an attack on the “perfect city” thinking of her day and closes with a meditation on cities as problems of “organized complexity.” She spends the intervening pages of the book exploring the natural ways that cities succeed and fail, often celebrating urban arrangements that learned planners saw as backwards. As her work illustrates, once we stop treating cities like simple machines that can be controlled, like set pieces for our own particular vision of the world, we discover something remarkable. We discover systems of incredible complexity, maintained and advanced by a dynamic ecosystems of the small plans of millions of individual planners, each with their own dreams and talents. We find objects of study infinitely more interesting than the stale content of master plans, from community self-governance to innovative new forms of urban living. As with culture, as with economics, as with cities, the age of imposed, top-down control is over. A liberal approach stands to give us something far more valuable than the utopian visions of yesteryear.