While at university I read a research article that demonstrated how we are more likely to trust research findings that accord with our world view, and more likely to mistrust or disregard evidence that doesn’t support our view point. The research explored the attitudes of people with regards to the death penalty, and how their views were changed after examining evidence that supported or disputed their beliefs. The “evidence” that was shown to the research participants was created specifically for the purpose of the study but presented as fact, and the two equally ‘rigorous’ studies showed that the death penalty either did, or didn’t have a deterrent effect.

The study showed that those who already had strongly held beliefs in support of the death penalty were more inclined to disregard or mistrust evidence which showed that the death penalty was not an effective deterrent. Those who already had strongly held beliefs against the use of the death penalty were more likely to disregard or mistrust evidence that showed that the death penalty was an effective deterrent.  In addition, the process of examining the evidence had a polarizing effect, leading both the pros and the antis to become even more convinced of the ‘rightness’ of their views.

I remembered this study today as I was reading an article in the Guardian about declining levels of drug use amongst people in the UK.  It details the latest release of British Crime Survey figures,  and reports that:

the number of adults in England and Wales who used illicit substances in 2009-10 – 8.6% – was the lowest recorded since the study began in 1996. Among 16-24-year-olds, the picture was the same, with just 20% saying they had taken drugs in the previous year – another record low, and a third lower than the proportion 15 years ago.

The Guardian article also cites a Mixmag article that showed:

there were found to be large year-on-year falls in the number of people taking cannabis (by five percentage points), ketamine (10), ecstasy (five) and cocaine (20)

I haven’t been back to either the original British Crime Survey or Mixmag reports to check either the figures, or for any caveats that the researchers may or may not have put on their findings, or to check how these reports fit into a year on year trend.

But what struck me, as I was reading this, was how much I want to be able to dispute the figures. I really don’t want to see any evidence that prohibition might be working (in the context of reducing the number of people in the UK who take illegal drugs). I even feel ambivalent about the reductions in drug use. As I was reading I was thinking that even if these reports are indisputable enough to pass the “Bad Science” test, I already have other  pro-legalization back-up arguments in place- about the global harms of prohibition, and the costs to society of criminalization, and the dangers of poorly regulated substances for those who do take them, etc.  My reaction to the article really made me me question how open-minded and rational I am when it comes to evaluating the evidence for and against the effectiveness of prohibition.