The Neighborhood as Unit of Analysis

The most common error in thinking about complex systems is the error of scale. A pesticide appropriate at the scale of a single farm destroys the watershed. An antibiotic appropriate for a single patient breeds resistance when prescribed to a population. Jacobs made this observation about cities with a specificity the planning profession has still not fully absorbed. The neighborhood is the unit at which urban vitality operates. Not the city — too large, its uniform policies destroying the specific conditions of particular places. Not the block — too small, unable to sustain the diversity that produces vitality on its own. The neighborhood is the scale large enough to contain diverse uses and varied building stock, but small enough that people can know each other's faces and sustain the informal social norms that make a place livable.