Criminal Propensity is Normal
Why might Criminal Propensity be Normally Distributed?
Normal distributions are often found in nature. The reason for the prevalence of normal distributions has to do with a natural approximation of the central limit theorem. The central limit theorem states that when there are many independent randomly distributed correlates of a phenomenon, the phenomenon tend to become normally distributed. There has been little discussion of the normalization process with regards to criminal propensity. This would seem to be an oversight that should be addressed.
Why Do Human Factors Seem To Be Normally Distributed?
Many human factors seem to be normally distributed. That is, they follow a “bell” shaped distribution. This seems to be the case for human factors such as height, weight, and intelligence. The reasons for this have to do with the cumulative operation of many random sources of variation. For an explanation and argument against using the central limit theorem as an explanation for natural phenomenoa, see the article by Aidon Lyon called Why are Normal Distributions Normal?. Although there are some reasons to question this idea, it would seem that with the limitless number of independent sources of variation in the factors that cause crime, the propensity for crime should follow something approximating a normal distribution.
An Inconvenient Fact
Although it is likely that criminal propensity is normally distributed in the population, criminologists have spent remarkably little time exploring this possibility. The reasons for this are not clear, since the concept of a normally distributed criminal propensity are found as far back as the mid-1800s with the work of Quetelet. One possibility is that normality has a resemblance to other biological characteristics. If criminal propensity is biological in origin, this can lead to calls to discriminate against certain peoples based upon characteristics such as race or intelligence. These concerns ignore the multi-variate nature of criminal propensity.
The Bell Curves
The evidence suggests that criminal propensity is not due to biology alone. The bell curve for criminal propensity is the resulting sum created by adding many bell curves together. These include the biological, psychological, sociological, environmental, and timing curves, plus many more factors that have not yet been discovered. If one wants to change the population distribution of criminal propensity, the effort can focus on any one of these areas.