It is always morbidly fascinating when someone famous makes an idiot of himself, as Professor Stephen Hawking has just done. Seventy-one now, he has had a career at Cambridge University as a theoretical physicist. His book, A Brief History of Time, was a big bestseller written for the general reader, but I must confess that I am too backward at physics to have got beyond a page or two. Hawking suffers from motor neuron disease, and shows great courage in dealing with it, so the public, me included, is on his side. He knows about adversity, then, and as a scientist he also knows about verification. In spite of that, he suddenly announces that he is boycotting Israel. He had accepted an invitation to a big conference there, and now has withdrawn on the grounds that Israel denies rights to Palestinians.

A unanimous wave of criticism has hit him. No doubt he’s been naïve.

Politics is not his line. He happily visited China and Iran without making statements about civil rights. He couldn’t communicate at all without a machine containing a chip designed in Israel — so will he boycott himself? His decision seemed more and more inexplicable until it was revealed that as many as 20 academics had lobbied him to stay away from Israel and one of them was Noam Chomsky.

A Brief History of Chomsky would be as impenetrable a book as Hawking’s. American and Jewish himself, he inhabits a mysterious universe in which everything wrong is the fault of Americans and Jews and everything right is to the credit of enemies of Americans and Jews.

Among other inversions of reality he has defended Holocaust denial and genocide in Cambodia. To read his books and journalism is to find oneself at Lewis Carroll’s Mad Hatter’s Tea Party where familiar things and meanings dissolve into a web of fantasy that is seamless. Now and again, I receive letters from strangers who in Chomskyesque style interpret events in a single obsessive dimension, alleging for instance that the Queen of England controls drug trafficking or President Bush organized 9/11. On their own demented terms such fictions are often so consistent that even intelligent people can fall for them, as seems likely to be the case in the Chomsky-Hawking interaction.