Subtracting to the Better City
The wisdom of pruning
The other day I was listening to an episode of Hidden Brain, where host Shankar Vedantam was interviewing engineering professor Leidy Klotz about his new book, Subtract on how engineering and design often neglect subtraction as a strategy.
For example, removing road lanes or entire highways can actually reduce traffic congestion more than adding lanes. One story Leidy tells is that of The Embarcadero freeway in San Francisco, a congestion-inducing double-decker highway built in the 1950’s that cut the city off from its historic waterfront and views of the beautiful bay.
The idea of removing it was such a counterintuitive idea that, even after decades of dysfunction, voters roundly rejected the idea nearly 2:1 in a 1987 referendum. Even legendary local columnist Herb Caen was against the demolition, writing that tearing it down was “an even worse idea than building it.” Fortunately for San Francisco, the 1989 Loma Prieta earthquake damaged the double-decker highway and public sentiment began to turn. In 1991 the whole highway was removed in favor of a surface boulevard that has become a tourist destination, transit corridor, and desirable area for new development.
Another example from the episode that stuck with me was Leidy’s description of an office brainstorming session. At the end of the session over 90% of the ideas suggested were new things they could add–new projects, new grants, new work, new staff, etc. Less than 10% of the ideas involved stopping doing something they already did. Recall for yourself the last time you participated in a brainstorming session: what came more naturally, adding ideas for more things you could do, or things that you could stop doing?
This story crystalized something that I’ve intuited in the past while listening to panels describing various problems: say the housing crisis. At the end of the session, when the presenters are called upon to offer solutions… all their ideas are about adding programs: new regulations, rental registries, inclusionary zoning, rent control, new paperwork and forms to fill out, and so forth. When I hear those sessions, I think: what we have is a system that doesn’t build enough homes at a low enough price… and we think that adding administrative complexity will make it easier for us to build more, and more cheaply?
There is another way to arrive at good outcomes, however. The patron saint of the Strong Towns movement, Nassim Taleb, in his book, Antifragile, expands on the ancient idea of via negativa, arriving at some truth or idea by way of understanding what it is not, by applying it to actions. Following via negativa, the goal is to avoid bad consequences rather than engineer ideal outcomes.
So instead of designing the perfect highway, stop building more roads (that we can’t afford to maintain, that we can’t predict future demand for, and that destroy neighborhood wealth). In fact—consider subtracting from your road network. The via negativa approach recognizes that, in a system of distortions and complexity, it is impossible to predict the results of our actions, but by working to simplify and reduce distortions we make it possible for individual agency and feedback systems to untie our knotty problems.
One place in particular where I see the value of doing less is in zoning reform. I’m a former zoning administrator and I have a soft spot for zoning regulations. But I’ve lived the ways in which complex layers of rules lead to senseless outcomes. I love my garden too, and one of the things I’ve learned from gardening is the importance of pruning and thinning. Often cutting a plant back, removing side growths or a leader, opening up air between leaves, and even removing while plants helps improve the health of your garden.
What if we applied the same logic to zoning reform? By cutting back the less productive regulations, we can focus on the most important regulations. What if for each new rule you want to add, you must pick two existing rules to do away with? Such a principle might focus the mind and help us create simpler, more focused, and ultimately effective development regulations.
Another thing I learned from our Covid garden–you have to be physically around to tend to a place. When Covid came in the spring of 2020 we were froced to subtract most of the activites, trips, and other engagements, and spend a lot more time at home. We were working in the garden alongside the kids playing every day, spending a lot of hours on the same few thousand square feet. Stewarship, I learned, depends on deep, consistent time and close attention to a place—a garden, or a building, or a street—which in turn means subtracting some plans, activities, or other ambitions.
My ability to prune and fertilize, to plant seeds and watch them grow depends on my literally being there, not somewhere else, doing something else. Which brought me back to a favorite essay by Daniel Herriges at Strong Towns called Delight per Acre that I find myself returning to frequently– go read it now :)
What’s the point of cities–fiscally or environmentally sustainable or not–if we do not love them. Without love for our places, without joy, we will simply not take care of them, and they will not take care of us. Daniel uses numerous examples to show how what we love best about streets, buildings, and gardens depends on the careful execution (and maintenance) of details. Which is simply not something that can be done “at scale.”
If we want a wealth of delight per acre, we may have to do a little less.