The lowest and vilest alleys in London do not present a more dreadful record of sin than does the the smiling and beautiful countryside. - Sherlock Holmes, The Adventures of the Copper Beaches
After all the randomization, cleaning and measuring, now comes the philosophical pondering. Why did we see the low rates of crime we did in the areas around the greened lots? This is not a question to which we can provide a definitive answer, at least not from this study alone. However, we can discuss some of the prevailing ideas in this space and consider which among them are most compelling.
Eyes on the Street
The authors offer a number of summary comments detailing the potential
mechanisms that may explain the reductions in shootings. The first arose
from their qualitative research — survey interviews — which suggested
that the greened vacant lots encouraged nearby residents to be more likely to
leave their houses to walk by or spend leisure time in the lots that were
previously used for illicit activities like drug dealing (Moyer et al. 2019).
The decrease in crime then, under this premise, arose from the increased number
of residents using the vacant lots as it provided an increased number of
undesirable witnesses for those who might otherwise become involved in a
shooting. The author’s cite this as a possible manifestation of
routine activities theory, which posts that predatory crime is
most likely to occur when a motivated offender, a desirable target, and a lack
of effective guardians converge in time and place (Cohen and Felson 1979).
This is a powerful idea, and while the work cited was published in 1979, there was an even earlier argument for these ideas in the 60’s. In one of the seminal works of urban planning, “The Death and Life of Great American Cities”, Jane Jacobs lays out a similar, simple thesis for what makes city streets safe (Jacobs 1959):
… [T]here must be eyes upon the street, eyes belonging to those we might call the natural proprietors of the street. The buildings on a street equipped to handle the strangers and to insure the safety of both residents and strangers must be oriented to the street. They cannot turn their backs or blank sides on it and leave it blind.
Personally, I find this idea so compelling because it is so simple. We are innately social creatures and care a lot about what others think about us. We simply act differently when we think others may be watching, no matter our capacity for ill-intent. Still, there may be more at work here then simply increasing the number of eyes on the street.
Social Cohesion and Broken Windows
Figure 1: Figure from Tomas Castelazo, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
There are two more sociological theories that may be at play here. The authors cite both collective efficacy theory as well as broken windows theory as being relevant in their final comments (Sampson, Raudenbush, and Earls 1997; Kelling and Wilson 1982). The first theory speaks directly to the idea of social cohesion highlighted in this blog’s introductory motivation: that members of a neighborhood community will attempt to self-regulate one another, separate of a more formal process, in order to avoid problems like those that may arise with the police. Additionally, they’ll also act to encourage other behaviors that promote shared values. The authors in our paper argue that the cleaned up vacant lots may have promoted this sense of social cohesion, prompting a renewed willingness to act for the common good and normalizing a higher standard of behavior in the community.
Building off this idea, the broken windows theory posits that a sense of disorder may promote further disorder — if one window is broken in a building, the rest will soon be broken. By restoring some sense of “order” to the built environment, the greened and mowed vacant lots reduced the inherent psychological feeling that crime was appropriate. It may be worth noting here, briefly, that what constitutes a sense of order broadly is not necessarily uniformly understood, but for our purposes we’ll consider “order” in this context to mean the vacant lots without trash or apparent lack of use.
Which is it?
All of these ideas represent plausible mechanisms by which the greening and mowing intervention effects on gun violence may have occurred. We can’t really know which, or to what extent one theory may have had a larger role to play than the others from this analysis but future work that target these theories more specifically could. For example, one might be able to scrape comments and photos on social media sites like Nextdoor or Twitter that mention the vacant lots, and try to identify how the attitudes community members communicate about these spaces may comport more or less with the theories stated above. For my part, I think each of these theories probably plays some role, though I have to think that the eyes on the street may be the most impactful in discouraging misdeeds.
Looking Ahead
This post represents the final writing I plan to do on this paper specifically, though I hope to reference it again in future work. Specifically, I hope to build on the ideas discussed here to examine different ways crime manifests in cities during times of duress — like, say a pandemic — as well as consider alternative methods for modeling crime. Regardless, it is my hope that having read some or all of this case study, you’ve come away with an appreciation for both the importance of the built environment as it affects one of the most important aspects of our lives — safety — as well as gained some understanding of the difficulties in how we measure and analyze these phenomena.
The pressure of public opinion can do in the town what the law cannot accomplish. There is no lane so vile that the scream of a tortured child, or the thud of a drunkard’s blow, does not beget sympathy and indignation among the neighbours, and then the whole machinery of justice is ever so close that a word of complaint can set it going, and there is but a step between the crime and the dock. But look at these lonely houses, each in its own fields, filled for the most part with poor ignorant folk who know little of the law. Think of the deeds of hellish cruelty, the hidden wickedness which may go on, year in, year out, in such places, and none the wiser.” - Sherlock Holmes, The Adventures of the Copper Beaches
Acknowledgements
Thanks to Robert Svoboda for reading and offering comments on this article.