I was on CBC Radio 1’s Day 6 last weekend, talking about some of the reasons why scientists can’t answer key questions about guns — whether current gun policies do anything to reduce violent crime, for instance, or whether more guns cause less (or more) violence. In a related debate, you should also read the article on the science of video games and real-life violence that Brandon Keim wrote for PBS’ NOVA. The truth is that this branch of science also has big problems connecting cause and effect and, as with gun policy research, the best kinds of experiments can’t really be done for logistical and ethical reasons.