Ants and Jane Jacobs

To continue the “ants” discussion…
When people talk about the how bottom-up, emergent systems are superior to top-down planned systems, they often quote Jane Jacobs.
In “Death and Life of American Cities“, Jacobs writes about the lively, crowded, haphazard streets of her Greenwich Village neighborhood, and compares them to the planned high-rise developments and efficient elevated highways of her nemesis, developer Robert Moses.
In the 50s and 60s, developers like Moses swept into run-down urban neighborhoods bearing a vision of “cities of the future,” demolished the houses and stores, and replaced them with sterile projects that turned into slums worse than the neighborhoods they replaced.
Jacobs explains why the organically-grown neighborhoods are better than the planned developments. The variety of newer and older structures help the neighborhood support a diverse population — elderly folks on pensions, young folks starting out, families with children. The mix of commercial and residential properties helps keep the neighborhood safe, since the neighborhood is populated day and night, weekdays and weekends. The sidewalks and front-porches enable people to stroll, chat, and look out for each other. By contrast, the un-inviting plazas and parking lots surrounding high-rise buildings are often deserts where the ill-intentioned can prey on the unwary without being observed.
Simply by observing local norms, people extend the neighborhood by inviting their elderly parents to move in, buying and upgrading a ramshackle storefront, and sweeping their walk. These activites aren’t centrally planned, individuals don’t get permission to do them, and, in sum, they add up to pleasant and safe neighborhoods.
But looking at Greenwich Village as an example of ant-like emergent behavior misses a lot of the story.
There is a large substrate of of social and cultural structures that enable these unplanned activities to create a pleasing and diverse order. The neighborhood has sewers and clean running water. Without these, the city neighborhood would harbor endemic infectious diseases. There is a fire department which protects the block if a single house catches fire. There are people with the technical and project-management skills required to design and repair plumbing, heating, and electrical systems.
A colony of ants couldn’t create Greenwich Village. Neither could a tribe of hunter-gatherers. There are underlying levels of infrastructure — some of which require planning — in order to enable the higher-level decentralized behavior.
In order to facilitate decentralized, unplanned human systems that work, it’s important to think about the ordered infrastructure patterns — like sewer systems, and ordered nodal activities — like designing an electrical system — that are needed enable the larger unplanned pattern to emerge.