Urban density after Jane Jacobs: the crucial role of diversity and emergence

Abstract

Background: In the early part of the twentieth century, planning theory and practice always voiced strong opposition to density. The error of this insistence was persuasively argued by Jane Jacobs in the 1960s. Subsequently, planning theory and practice came to recognise the importance of density, but this return to favour requires remaining constantly alert to the possible dangers and pitfalls. Methods: Critically considering the traditional and contemporary urban planning literature and the empirical evidence in the recent economic and geographical research, this article investigates the whys and wherefores of density in urban planning. It addresses two main questions: Is urban density really desirable (and why)? Is it effectively manageable (and how)? Results: Density per se is meaningless unless it is a tool or condition for achieving something further. And even if the instrumental function of density were to be acknowledged, it is crucial to take into account that density is not solely (or merely) a tool which—in certain conditions—can be useful in reducing commute times and minimising the encroachment on undeveloped land. Its primary advantage concerns favouring the concentrated diverse admix of human preferences, tastes, abilities, know-how, uses, activities, and so forth. Conclusions: After having expressly laboured to avoid it for so long, the aim is not to create density directly, but to open the door and allow density to happen in our cities, thanks to more abstract and general planning rules.