No liberal could possibly agree to such a law. After the outrages of 7/7, I did ask myself whether my liberalism had survived the explosions. Before all this, I used to hold the view that the state should not require require the citizen to believe anything. I appreciate some see it as either a "negative" in the Isaiah Berlin sense and/or naive, but I still think this. The Platonic view is that firstly, the truth can be known, and secondly, that there's no reason to assume that the truth could not be defeated in a social struggle for ideas. It follows from this that restrictions on the free expression of ideas is permissible.
It's by no means absurd but I think Mill correctly identified one of the inherent dangers in this argument: legal protection for ideas can and does lead to them descending into dogma, as their rational basis fades for want of any challenge to them. Provided they haven't enjoined others to go and do likewise, I'd prefer the cheerleaders of Al-Qaida to be out in the open where they can be argued with. And the same goes for the religious of all stripes. In my lifetime, I've seen the whole subject of religion become a virtual free-speech zone in this country over the last twenty years or so. I dare say I'm being short-sighted or something but the benefits of this custom are not at all obvious to me, to say the least.
Beyond this, one can foresee a couple of practical difficulties with this proposed legislation. One rather depressing problem is the sheer number of people who would fall foul of this law. Now, I'm sure the legislation isn't designed with the intention of jailing apologists like Ken Livingstone (although not doubt Blair has a wee fantasy about that), but for those who would, it would surely be if nothing else a tactical error to have stupid arguments about what constitutes "terrorism" given the status that would come from a criminal trial?
And although I find the sheer number of people willing to justify barbarism a very melancholy reality, in terms of the actual material threat they represent, I think it's possible to exaggerate the potential danger. There are not a few justifiers of terrorism in Glasgow. A small minority were directly involved in Northern Irish terrorism (both camps) but - and I hope you don't think I'm being glib about this - most of those who casually supported sectarian murders in someone else's backyard were and are complete and utter morons who represented a threat to themselves, more than anyone else. Not a perfect parallel, by any means but I do not think that the approval of suicide-bombing, repellent though that is, makes someone a potential bomber themselves.
At the end of this post, I said - or was trying to say in rather undignified language - that we should have more confidence. It's a tragic loss of this confidence that is represented by the pathetic hand-wringing search for what we did to invite this. But it would be to extend the tragedy if we forgot that it's ability and strength to protect the rights of those who wish for its downfall is the glory and wisdom of democracy.