A key goal of the Harper government's new anti-terrorism bill is to stop the domestic recruitment of our youth by Islamist extremists. It will do no such thing.As Stephen Harper noted in a speech last Sunday, the bill is designed "to help authorities stop planned attacks, get threats off our streets, criminalize the promotion of terrorism and prevent terrorists from travelling and recruiting others." In other words, the bill is focused squarely on enforcement.Now no one doubts that good enforcement is essential in the fight against terrorism but, as any street-wise cop knows, it is not enough to stop such crimes from recurring.  For that we need what experts call crime prevention.The usual approach is to examine the circumstances around a crime, find its key causes, and then look for ways to change them to prevent anyone from carrying out the same crime in future.After the Boston bombings, Harper made clear what he thinks of this approach: it is sociological nonsense. In his view, crime prevention results from a combination of good enforcement and tough penalties.But even if one agrees with his philosophy, it takes only a moment's reflection to see that Islamist extremists are a glaring exception to it. The terrorists' willingness to blow themselves up to advance their cause makes the whole idea of deterrence a non-starter.So the Prime Minister can say what he wants, but the lesson is clear: If he really means to stop the terrorists from recruiting our youth, he needs to adopt some kind of “sociological” approach. The question is, 'what kind?