BOOKS: A little learning...

The Know-It-All By A J Jacobs HEINEMANN pounds 10.99 (386pp) pounds 9.99 (free p&p) from 0870 079 8897

It must have seemed a great idea. Take a self-confessedly dumbed- down thirtysomething man, an editor at Esquire magazine, and set him to drag himself on to the high ground of learning by reading the entire Encyclopaedia Britannica, from a-ak to Zywiec.

Not just "seemed", either. It was a good idea: a clever and interesting quest - can sheer weight of raw data change us? - and a fine opportunity for a satire on popular culture; for a two-pronged attack on the silliness both of dumbing-down and of those who classify "knowledge" as a commodity to be deployed as a social weapon; for an exegesis on wonder; even for an investigation into how the appetite for learning can run out of control and drive one mad, as anyone who has spent any time in our great academies will see merely by looking out of the window (or into the mirror).

But there's a problem. AJ Jacobs is too much a man of his culture to do more than occasionally hint that the knowledge he is acquiring as he wades along is affecting him in any way, other than providing something to joke about. It wouldn't do otherwise. Successful New York magazine guys do not admit to wonder, because even Aristotle knew where that led: "It is thanks to wonder that people now start - and originally started - to philosophise. They wondered, at first, about the obvious problems, then... extended their wondering to greater questions. . . about the origins of the cosmos."

At the heart of a media culture founded on neuroses and voyeurism, a reputation for philosophising about the origins of the cosmos will pretty soon turn into a reputation for living in a cardboard box. Not an option. What is left, then, is a selection of headwords from the Encyclopaedia, loosely grafted on to anecdotes about Jacobs's (rather shadowy) wife, his friends, his apartment (got ready for the children they are having difficulty conceiving), and his intense competitiveness with his father, who once worked out the speed of light in fathoms per fortnight. And the jokes.

Jacobs's jokes are mostly bathos, and bathos means that far too much has to be cut down to one-size-fits-all. In American popular culture, that means hat-on-backwards, shambling, rude-boy, butthead git.

"Your average 19th-century Frenchman," he says (writing on Flaubert's doomed autodidacts in Bouvard et Pecuchet) spent his time "sitting around eating pastries, ignoring basic hygeine, and persecuting Jews." On Blake's marriage to "an illiterate peasant woman": "I hope they had amazing sex, because I can't imagine the conversation was too lively." On the meaning of gymnasium: "The literal Greek translation is `school for naked exercise'. Which made towelling off the stationary bike even more important." And so it goes on.

The trouble is that bathos relies on the parody of witlessness. Let real witlessness creep in, and it fails utterly. Nor will it work if the reader is unsure of the irony. Is the writer writing dumb but thinking smart? Or is he inviting him to join us down there? But "down there" is dangerous. The author who says (whether honestly or as a marketing device) that "I am just as dumb as you are" is also saying that "You are really as dumb as I am (pretending to be)". It is the implicit insult at the heart of pop culture, and the opposite of the Britannica, which assumes the reader is ignorant but not dumb.

The Know-It-All knows its audience. "Imagine Bill Bryson meeting Schott's Original Miscellany and Woody Allen at a party," it conjures. Really? The master of assumed dumbness, some lists, and a steely egomaniac who has made a career out of phoney diffidence?

Is this the company Jacobs wanted to keep? Or is he less dumb and more of a mensch than his eye for a good sale (the book is being made into a film; how?) and his reputation in Trivia City will allow him to admit?

I suspect the latter, and perhaps one day he will come clean. It's not so hard. As Gian Biagio Conte said of the great ancient encyclopaedist Pliny, what counted, in the end, was "the capacity to be astonished and the will to astonish". But that is just so, like, uncool.

Michael Bywater's `Lost Worlds' is published by Granta