When men cease to believe in God (or so G K Chesterton allegedly said) they don't believe in nothing; they believe in anything. The first time I used that serviceable quote, some spoilsport wrote to point out that it has no printed source. In which case, Chesterton damn well ought to have said it, as it grows evidently truer by the day - especially if you stretch `God' to cover reason, progress, freedom and all the other secular absolutes that arrived with the Enlightenment.

Take history, and the conviction that it moves in a coherent direction, propelled by forces we can understand. As children of Enlightenment, liberals and Marxists alike trusted in this creed, but now its foes multiply. Last year, in a volume of `What if?' hypothetical essays, a group of modish anti-progressive historians scoffed at this old determinism. They gloried in the role of chance, character and even `chaos' in patterning the past. Edited by Niall Ferguson, Virtual History (now a Papermac, pounds 10) reflects a rising trend. Farewell, the iron laws of class, capital or climate; and welcome back to the foibles of Great Men.

So what happens when a truly wayward driver takes over this renovated motor of history, fuelled again by personal quirks and contingent events? As a warning of the worst that can result, Ferguson and friends should read The Jew of Linz by Kimberley Cornish (Century, pounds 17.99).

Cornish, an Australian philosopher, maintains that the chance proximity of the adolescent Adolf Hitler and Ludwig Wittgenstein at grammar school in Linz in 1904 set the course of the 20th century. The future Fuhrer, he argues, conceived a loathing for the steel magnate's vain son that drove his anti-Semitism from beer hall to death camp. Meanwhile, Wittgenstein became a Bolshevik, went on to overturn philosophy at Cambridge, signed up as a Soviet agent and then recruited Blunt, Philby and the rest in pursuance of this schoolyard spat. Behind the vendetta that shaped our epoch lay rival versions of an occult theory of collective mind which both tyrant and thinker derived from Oriental mysticism.

He can't be serious? Alas, he is. As a bizarre showcase of the paranoid style in history, The Jew of Linz would be hard to beat (although some recent books about Jung have run it close). My point is that this sad obsessive fantasy displays the depth to which ideas about the past can sink once you dump structural causes and simply chronicle the random collisions of actors who move the world (as Hitler desired) by Will alone.

Cornish deserves our sympathy: somehow, an intriguing thesis about Wittgenstein's openness to Eastern thought has got wrapped up in a lot of hare-brained stuff that should never have seen cold print. Century (part of Random House) deserve no sympathy: again, they prove Britain's airhead publishers will peddle any quasi-occult tosh for a quick buck and a newspaper extract.

As for the partisans of Chaos History, they should ask themselves whether, having rubbished the idea of the past as `tram journey' down fixed, rational grooves, they can live with the popular notion of it as a playground squabble between Superbrats. On balance, I'd still rather be a strap-hanger in a streetcar than a conker in the shorts of Hitler - or even Wittgenstein.