Friday's first episode of Simon Schama's paradoxical history of the future of the United States featured stunning widescreen landscapes of the American West and gruelling close-ups of its presenter. It struck me afresh that Schama, with his unAmerican teeth, is anything but a television natural: he bobs weirdly, gesticulates inappropriately and seems to have difficulty in managing his breathing during his longer to-camera addresses. Yet the stories he tells are without fail interesting and original. The American Future was exceptional even by his standards.

It was a tale of America's conquest of its western frontier and a prediction of its coming defeat that reduced oil to a walk-on part. Its subject was water, specifically the Colorado River, charted by a one-armed Civil War hero named John Wesley Powell in 1869 when a large patch of America was still labelled on maps “Unexplored”. Powell was out to make a reality of President Andrew Jackson's injunction to civilise the West, but as he sailed down the river sitting on a wooden armchair strapped to the deck of his boat, he had to report an inconvenient truth. This was a landscape of the Grand Canyon. It demanded respect and would not admit conquest.

Others, such as William Ellsworth Smythe, founder of the journal Irrigation Age and author of The Conquest of Arid America, disagreed and America got Las Vegas anyway. But we know about indefatigable American optimism. Here Schama gave us something different, the nation's counter-tradition of realism. Powell sat in a line of doomsayers that included Hugh Bennett, the prophet of the 1930s dust bowls, and Jimmy Carter, who gave warning just before being kicked out of office, that if America succumbed to a dream world it would wake up to a nightmare.

The pessimists have always been unpopular but they always turn out to be right. Locked in a nine-year drought, Lake Mead, dug out of the Colorado River, the largest man-made reservoir in the world, is simply running out of water. Las Vegas's water inspectors, issuing fines to owners of errant garden water features, may not, one felt, be quite equal to the challenge of global warming. It was a fascinating history lesson, right on the money for this “moment of truth” election, and told without one clip from Chinatown.

Schama had an argument and illustrated it brilliantly. Stephen Fry last night was In America and that was about as near to argument as his programme got. Instead as Fry fitted into the laziest of programme templates, the journey, he issued any number of observations, all of them generous, most of them pedestrian. Ben & Jerry's ice-cream was, he observed as he held a tub of self-styled Even Stephen, “quite cold”. “But in a hard and unpleasant world we need ice-cream. That's my feeling.” At worst, they were wrong. Easily impressed by a New Hampshire house party for the Presidential never-was Mitt Romney, he insisted: “All Americans have a sense of great connection and pride about their democratic beginnings and their sense of being involved in the democratic process.” Has Fry actually looked at turn-out figures for American elections?

So why did Fry, the quintessential English gent, get this gig? For the same reason he gets every gig: unlike Schama, the camera loves him. For decorum's sake, however, he pointed out that because his father had been offered a job at Princeton University he was “very nearly born in America”. Had he been, he would have been called Steve. Ha-ha. Actually, no, he wouldn't have been, because his family would still have been English and, anyway, aren't there Brits who trade under the name Steve?

Yet this near fact had, he insisted, given him a lifelong fascination for America. Maybe. But then he also declared that it had always been his ambition to look up a submarine periscope and to enter a Mafiosi hide-out in Queens. For sure Fry has realised one ambition: to get a long holiday paid for by the licence-fee payer.

At least he no longer corners the market on mental illness. All inquires should now be referred to Tony Blair's old press jackal Alastair Campbell who, in Cracking Up, relived in extraordinary detail his bizarre breakdown in 1986 and his subsequent, and continuing, bouts of depression.

Other people hear voices in their head: Campbell heard brass bands. Trying to work out which came first, the drinking (16 pints a day and a bottle of Scotch) or his mental illness, Campbell wore a stony face throughout. The exception came when he recalled how he had madly figured that if he could imitate Taggart's “granite-carved smile” he might be let out of his mental hospital. He summoned a nurse and grinned. Campbell laughed at his madness. That was fortunate, for it relieved the tension for us too. Sadly, to say there is nothing funny about mental illness is just not true.

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