At first glance, the connection between the exalted philosophy of John Rawls(1921-2002) and the mundane world of urban planning is not readily apparent. But upon further analysis, it is obvious that the two are inextricably linked.
America was a nation of yeoman farmers throughout its first century. Although some farmers were more prosperous than others, the differences in their circumstances were not usually enormous. They faced similar challenges and hardships in making a living by cultivating the soil. In the late 19th century, however, America became an urban nation. The cities had vast slums. Further outside the cities, there were comfortable suburbs. The extremely rapid and haphazard growth of cities helped create the inequality that prompted Rawls to write his magnum opus, A Theory of Justice.
Rawls' central tenet was that people should have equality of opportunity. A child born in a crime-ridden slum does not have the same opportunities as those available to a baby born in an affluent suburb. All people should enjoy a basic standard of living, but poorly designed and maintained cities made that impossible. Therefore, urban planners need to be mindful of social equity at all times: All people deserve decent housing and adequate sanitation. The equality of opportunity that Rawls sought was simply not attainable as long as the neighborhoods into which people were born were so unequal. All communities should have, for example, schools and swimming pools. Cities and their neighborhoods must be at least somewhat equal for Rawls's veil of ignorance to function.