PB: I think that’s exactly right. You might say that Michael Gove is presenting the demand side of the problem. “Who are the terrorists? What are their objectives? What are the cultural sources of their desire for revenge, their anger?” And that I push more on the supply side: “What can we do when we don’t know who the terrorists are?” After all, we still don’t know who committed the anthrax attacks. “What steps can we take when the nature or the source of the threat is ambiguous or maybe vague or maybe unknown?” But I think these two approaches are rather like the two parts of a pair of scissors: neither really works without the other.

MG: There’s been a lot of concentration obviously on questions of grand strategy – should the West have intervened here or there? Then or now? But of course you quite rightly point out that law has to govern international relations to an extent and that law crucially governs how we deal with the terrorist threat domestically. And of course we’ve had a debate in this country about detention without charge and so on but one of the things that strikes me, and I don’t know if you think this is fair, is that we’re all familiar with the critique of Guantánamo, and it’s a powerful and justified one, but it’s rare that the critics of Guantánamo say “OK, we’re dealing with combatants who deliberately operate outside the Geneva rules, who deliberately force us to think about conflict in a new way. What is the jurisprudence that should govern that?" And the genuine concern that I have is that for people who both want to see the rule of law preserved and who can see that there is a new type of threat, there is very little on the other side of the debate. There are very few attempts by people to say: “OK, this is how we develop law, this is how we develop jurisprudence to deal with it.”

PB: I think that’s exactly right and it’s one of the more distressing aspects of the way we address the problem. Law is the first and last stop-off for the decision maker. We don’t usually think of it that way, particularly people in the academy think tanks don’t think that way. But in the government, when a plane is shot down, when civilians are kidnapped, when some kind of extortionate threat is presented, the first thing you do is you see what the law provides, to see if your adversary has transgressed an international law. If conflict ensues and you are fortunate enough to prevail you go back to the law again and you say: “How can I compose this conflict on terms that are favourable to my interests?” So it is not the case in international relations that international law plays no role – it plays a crucial role. But when it becomes unstuck, in a strategic context, it forces the debate into two unprofitable and self-destructive channels. One is, as Michael was pointing out, the insistence on a law that does not contemplate the phenomena it addresses. I very much feel the Geneva Convention should govern the detention of non-POW combatants. But it is plain to me that the conventions right now deal with this quite clumsily because the language of Common Article 3 really doesn’t contemplate something like a global network of terrorists. The other sort of channel is represented by people who confront a law that is inappropriate or hasn’t kept pace with a changed strategic context and therefore feel that they have to just ignore it, just push it aside.