Cities are fantastically dynamic places, and this is strikingly true of their successful parts, which offer a fertile ground for the plans of thousands of people. – Jane Jacobs, The Death and Life of Great American Cities

For most of the field’s history, prominent urban planning theorists have taken for granted that cities require extensive central planning. With the question framed as “To plan or not to plan?” students and practitioners answer with an emphatic “Yes,” subsequently setting out to impose their particular ideal order on what they perceived to be, as Lewis Mumford put it, “solidified chaos.” Whether through the controlled centralization of Le Corbusier or the controlled decentralization of Ebenezer Howard and Frank Lloyd Wright, cities were to be just that: controlled. When in 1961 Jane Jacobs set out to attack the orthodox tradition of urban planning, it was this dogma that landed squarely in her crosshairs. With her characteristically deceptive simplicity, she invites us to ask, “Who plans?”

While many take Jacobs’ essential contribution to be her insights into urban design, her subversion begins at the theoretical level in the introduction to The Death and Life of Great American Cities. Despite their diverse aesthetic preferences, Corbusier and Howard share much in common. Both assume that planning entails the enshrining of a single plan and the suppression of all other individual plans. Both insist on imposing a “pretended order” on the “real order,” treating the city as a simple machine rather than a manifestation of organized complexity. Like Adam Smith’s “man of system,” each thinker was “so enamoured with the supposed beauty of his own ideal plan of government, that he [could not] suffer the smallest deviation from any part of it.”

Jane Jacobs’ critique of this orthodox tradition unfolds in three steps, closely following F.A. Hayek’s argument in The Use of Knowledge in Society. First, Jacobs emphasizes the importance of local knowledge. Where orthodox urban planners assume that the essential information in planning decisions can be gained through abstract principles and statistical aggregates, Jacobs makes the case for respecting local, man-on-the-spot knowledge. Consider the case of the East Harlem project, a centrally planned housing project sporting Corbusierian towers and giant lawns: housing officials viewed the project from an aesthetic and statistical viewpoint and loved it. Meanwhile, residents hated it; it segregated them from their communities, separated them from commercial uses, and left them with a big, useless lawn. Throughout the book Jacobs describes similar situations in which the needs and preferences of local residents clashed with central planners, with the conflict’s resolution all too often falling in favor of the “experts.”

Second, Jacobs knew that decentralized planning was the best way to make the most of local knowledge. Local residents often have the knowledge needed to make wise decisions about urban form. As Jacobs details throughout The Death and Life, the urban planner’s best course of action is typically to allow individuals to plan for themselves. As Hayek framed the problem of economic planning, the question should not be whether or not to plan, but rather who should plan? Put differently, we might distinguish between centralized and decentralized planning. Under a centralized planning regime, an individual or small group makes decisions for everyone regardless of what unique, local knowledge they may have. We see this often in cities today: Everyone must respect certain setbacks. All restaurants must offer unpriced parking. On the other hand, decentralized planning allows individuals to create their own plans and draw on their unique preferences and local knowledge. Where would I like to live? How would I like to interact with neighboring residents and businesses?

Finally, Jacobs clarified how decentralized planning helps create and maintain the spontaneous orders that make urban life work. Many of The Death and Life’s most beautiful passages concern the natural order that emerges from decentralized planning: sidewalk ballets that help keep streets safe and socialize children, diverse residential and commercial uses, and self-governing communities. These spontaneous orders are, in the words of Scottish philosopher Adam Ferguson, “the result of human action, but not the execution of any human design.” By allowing individuals to freely organize themselves in relation to one another, natural urban orders emerge without any central planning. Certainly it is not the case that all decentralized planning results in such orders. But as Jacobs points out, centralized urban planning, as it exists today, often hurts rather than helps.

For all the love Jane Jacobs has received from urban planners and policymakers since her first book was published, her greatest theoretical innovation seems to be largely disregarded. Cities across the country continue to centrally plan the minutiae of urban life, from obsessively detailed land-use regulations to impossibly ambitious comprehensive plans. Even many of those who have embraced Jacobs’ urban design insights scrapped her theoretical underpinnings, using rigid, top-down plans to create unsettling and unchanging recreations of natural neighborhoods and cities.

None of this should be taken to mean that there’s no place for central planning. Jane Jacobs, like F.A. Hayek, seems to be open to centralized urban planning in certain situations. However, the focus should remain on preserving a large sphere in which urban residents retain the right to engage in their own planning. A shift toward a more Jacobsian/Hayekian urban planning might occur in at least two ways. First, urban planners should focus on the kind of market failure uniquely important to urban life: externalities. Whether this involves creating a framework whereby neighbors may engage in a kind of Coasian bargaining or instituting broad prohibitions on certain harmful activities may depend on local conditions. It is clear that current centralized urban planning goes far beyond this.

Second, where some level of central planning is necessary, plans should empower rather than undermine choice. Consider the beauty of New York City’s grid: planned with remarkable foresight in 1811, the grid served as a blank slate for development, with accessible streets and adaptable blocks. Where grand plans of this kind are necessary, planners should emphasize flexibility in order to support the dynamism of decentralized planning. Where grand plans are not necessary, planners should stick to the trial-and-error of decentralized planning. Jacobs makes this case when she argues for embedding individual subsidized housing units into already functioning neighborhoods rather than tearing down and replacing whole neighborhoods. While an individual building may fail, its failure won’t be nearly be catastrophic as the failure of a grand housing project plan. Meanwhile, a small success can be studied, replicated, and scaled up when appropriate.

As Hayek did in the case of economics, Jacobs stood up to an urban planning orthodoxy that enjoyed the support of policymakers, academics, and all the “Very Serious People.” She celebrated the wisdom of everyday people when the relevant experts found answers only in statistical aggregates and economic calculus. Hayek and Jacobs defended the importance of local knowledge, illustrated the power of decentralized planning, and celebrated the sublime spontaneous orders that organize our lives. Yet their theoretical innovations went largely unnoticed long after their respective publications. Here, the two thinkers diverge: while Hayekian ideas have largely driven centralized economic planning into the dustbin of history, I suspect the Jacobsian urban revolution has only just begun.

Follow me on Twitter at @mnolangray.