D J Taylor: A man who knows what it means to be civilised – and chooses not to be

Just when you had assumed that the Breivik trial couldn't get any worse – with Thursday's revelation that its subject had wanted to decapitate a former Norwegian prime minister – it plunged into a yet more subterranean depth. Even to watch the fragments of Breivik's testimony come through on text services was bad enough – the self-proclaimed "nice" man who had deliberately hardened his heart to commit mass murder. God knows what the impact of this must have been in a mesmerised courtroom.

There are literary parallels here, the thought of art anticipating life long before the brutal reductiveness of the Breivik masterplan. Like someone out of Dostoevsky novel, here is a man who knows exactly how a civilised human being ought to behave, and yet consciously sets all moral scruple aside to follow the dictates of his warped ideal. The same stultifying scent blows up from Pure, Timothy Mo's new novel about Muslim fundamentalism in the Far East: purity is purity, however much dirt gets churned up in the course of its imposition.

In Breivik's testimony, too, lurks a hint that the trial will not accomplish what it set out to achieve, or rather that the achievement of it may throw up one or two implications more horrifying than the slaughter that set it in motion. The point of allowing Breivik to discuss his motivations and methodology before the world's television cameras is to establish whether he is mad or sane. Almost everything he has said so far suggests the latter.

Legal history is full of psychopaths eagerly dilating on the voices that directed them to behave in the way they did.

Breivik, on the other hand, either is, or gives a very good impression of being, a man who knew exactly what he was doing, weighed up the likely consequences of his actions and went steaming in regardless, confident that destiny was on his side. The voices he spoke of yesterday were saying "Don't do it, don't do it". This was the head ruling the heart, the conscious mind overruling instinctive taboos. Breivik also spoke of his trick of relying on "technical, de-emotionalised language" to talk about his crimes. "If I was going to use normalised language, it would not have been possible."

A wide-eyed dement, waved on by invisible hands, is in the last resort not responsible for his actions. On this evidence, the crystalline logic of the fanatic is a great deal harder to deal with.