Look, one wants to say to that father, young people worth their salt detest smugness, complacency and lack of vision, and the adult world can seem like that to them. Roth's beautiful, talented little Merry, who turns into a fat, aggressive spouter of expletives and political jargon, probably feels: "Mom, Pop, why don't you get it that not everyone wants to live in luxury and comfort?" There is a kind of American blindness about the novel. Add in the war in Vietnam, or some other faraway place, to justify bringing the message home with explosives, and we know why Merry does it. Still no one can say why monstrous destructiveness grips one child and not another. That's the Rothian anguish.

Against Roth, Garnett's real-life story suggests that terrorist susceptibility is often a product of upbringing. But if you suppress their unconventionality how can children grow up independent-minded and idealistic? Surely they can be good rebels, and discriminate among causes and methods? It's not easy. (A friend of mine who spent most of his life verbally fighting Communism was horrified at the thuggery of some prominent demonstrators in the tuition fee marches last December. In a last note before he died, he denied any element of student idealism about them.)

Two elements in Garnett's story about a youth who finally didn't commit a terrorist act seem to me to hit home. One is that he quite quickly strikes himself as ridiculous. The other is that he doesn't hate anyone. I haven't noticed other novelists or commentators single out the point but, given that there will always be causes that urge both real and pseudo-idealists towards violence, not to produce haters is the best any parent can do. The rest is a matter of chance and evil.