Definition
Broken windows theory is a criminology theory. It says that if small disorder or rule-breaking is left alone, people who see the signal let their guard down, and it can eventually spread into bigger, more serious crime. Political scientist James Q. Wilson and criminologist George Kelling published it in 1982.
One broken window sets off a butterfly effect
Picture a car parked in an alley. While its windows are intact, nobody touches it. But if one window sits broken for a few days, everything changes. People walking by look at the car and think, 'The owner must have abandoned this, or nobody is looking after it.'
From that moment, the mental barrier starts to collapse. People smash the other windows, steal parts, and scribble graffiti all over the body. Before long, the car is a heap of scrap metal. One small crack became a signal that nobody is in charge, and it pulled in bigger disorder.
People read the small clues scattered around them to figure out how far they can go here. A broken window is a strong hint that the fence of social norms around the place has already come down.
What happened when New York erased subway graffiti
This theory won worldwide attention through a case in New York City. In the 1980s, New York's subway was covered in filthy graffiti, and it was a frightening place where crime never stopped.
In 1984, the subway authorities started, surprisingly, not with violent crime but with scrubbing the graffiti clean. In 1989, the last graffiti-covered subway car was gone. In 1990, transit police began cracking down on fare evasion. From 1994, a new mayor and a new police commissioner widened this approach into a citywide crackdown on minor offenses. They judged that fixing the small, visible disorder first would bring back discipline and a sense of safety across the whole city.
At first, some experts objected and said violent crime and service problems should come before graffiti. After that, violent crimes such as murder and robbery in New York dropped sharply in the 1990s. So it is often cited as a leading example of how tidying up the environment can lead to crime prevention.
To be more precise
To be more precise, modern sociology and criminology add a few cautions when applying this theory. Many analyses argue that New York's drop in crime back then was not due only to erasing graffiti and cracking down on minor offenses.
The counterargument is that several positive factors worked together, such as the booming economy across the U.S. in the 1990s, falling unemployment, and shifts in the population makeup. Also, punishing small rule violations too heavily had a side effect: minorities and vulnerable groups faced excessive policing.
Still, broken windows theory remains valuable. Instead of just adding punishment to scare people, it teaches the wisdom of prevention: cut off the seeds of disorder early by first building a pleasant, open environment.
Common misconceptions
To stop violent crime, you only need to punish serious criminals harshly.
This theory holds that when minor offenses and a disorderly environment are left alone, the mental barriers fall, and the ground becomes fertile for more violent crime. However, there are different views on how large that effect really is.
Where you meet it
If one cigarette butt is lying on the street, other people walking by toss their trash there without guilt, and the spot turns into a dump.
In software development, if you leave small code errors alone, bugs pile up and the whole program becomes unstable.
In one sentence
This theory says that small disorder left alone can spread into bigger crime, so we should take care of small gaps in the environment first.