Security guru Bruce Schneier has written an insightful article for Wired about rational precautions for rare risks, and why the typical response after a rare catastrophe is usually psychologically satisfying but practically irrelevant.
He writes the article in the wake of the Virginia Tech shootings, which have caused a number of bizarre responses by people worried about whether it might happen again (banning fake guns in theatrical productions, for example).
Interestingly, they don’t spend their whole time thinking ‘how can we stop this person murdering someone’, as although this is the sort of thing that hits the headlines, it’s actually incredibly rare.
People who have already murdered someone are generally locked away and don’t pose much of a risk, but for someone who has never murdered anyone or never attempted to, predicting whether they will can be very difficult.
In fact, it’s difficult to gather data to determine whether your predictions are accurate or not.
Imagine you have a risk assessment that predicts that a person is highly likely to murder someone.
To best evaluate your prediction, you’d want to wait and see if it turns out to be true, but in these circumstances, you can’t. You have to intervene.
Once you’ve intervened, you don’t know whether your prediction was true or not.
Forensic mental health professions spend a lot of time thinking, as Schneier recommends, ‘have we done everything that is feasible to reduce the risk to the public based on what we know about the most common risks’.
In other words, they focus on the principle of maximising safety, rather spending all their time and energy on highly unlikely events that may be impossible to predict.
As they tend to be so frequently in touch with the legal system, their second line of thinking tends to be ‘if the extremely unlikely does occur, will we be seen to have done everything that was required by the courts’, because at the end of the day, the law is the final say on what is acceptable when predicting the unpredictable.