This chapter examines the first of four interrelated forces that impact the diversity and vitality of cities: the tendency of diversity to self-destruct. This happens when diversity is too successful, leading to the creation of “has-been districts” (242), which cause stagnation and decay in inner cities. Self-destructing diversity can happen in a variety of settings, including small street neighborhoods and large districts. It occurs when an area becomes extremely popular, creating competition for space. The affluent winners in the battle for space represent a narrow segment of the diverse uses that made the area successful to begin with. Less affluent dwellers and enterprises get squeezed out. Once this happens, the area gradually empties of users because it is no longer diversely successful. The place becomes visually and functionally monotonous. The economic disadvantages of low-density follow. Finally, the area’s “suitability even for its predominant use gradually declines” (243).

Jacobs proposes three remedies for self-destructing diversity. The first is zoning for diversity. The goal of this remedy is not to freeze conditions and uses, but to ensure that changes and replacements happen gradually. Jacobs refers to the second remedy as the staunchness of public buildings. Public and quasi-public bodies should staunchly establish buildings in places where they will add to diversity, rather than duplicate neighboring structures.