Rupert Cornwell: What Monty Python taught Uncle Sam

Out of America: In a troubled world, the US remains determined to 'always look on the bright side of life'

How are you today? Wonderful, you reply, and how could it be otherwise? Once, having been asked that question for the umpteenth time in the space of a few hours, I actually did say: "Well, since you ask, not so great." The response was a blank stare and bewilderment at this breach of the formulaic certainties of American life. Here, positive thinking rules. But maybe it shouldn't.

The thought occurred to me one afternoon last week, browsing in my local bookstore where I came across the wonderful Bright-Sided, by Barbara Ehrenreich. In recent years Ehrenreich has emerged as one of the country's shrewdest tellers of uncomfortable truths – most famously in Nickel and Dimed, where she goes underground as a low-wage worker, describing the daily struggle to make ends meet at the fag end of the American dream.

This time she takes aim at the mindset that to be happy and get ahead, you must always look on the bright side; as the song from Monty Python's Life of Brian urges, "When you're chewing on life's gristle/Don't grumble, give a whistle ..." Many indeed would argue that can-do optimism, the belief that you can achieve anything if you really set your mind to it, is what makes America great. Ehrenreich, however, is not among them. For her, positive thinking leads to self-delusion, where problems and outrages are ignored, and a ruthless capitalism is able to keep the country in its thrall.

Judging by what else was on offer in the store, she is ploughing a lonely furrow. Shelves groaned under such titles as One Small Step Can Change Your Life or Teaching Hope or How to Instantly Connect with Anyone. Work Hard, Be Nice, exhorted another. Or how about Getting Things Done, and Stay Rich for Life? If only.

A volume called Be the Change: How to Get What You Want in Your Local Community proves no area of life is immune to the therapy. All you need is the power of persuasion, but that too can be acquired. Just read Say It Like Obama and Win (although that particular title is a mite out of synch with the growing inability of the smooth-tongued commander-in-chief to get his way).

Back in 2005, someone estimated the total US market for such stuff at $10bn a year. Add in the rest – motivational speakers, self-improvement courses, and all the other "secrets of life" peddled by life-style gurus, preachers and plain old hucksters – and the total turnover of the positive-thinking industry these days may be double that.

When it works, of course, positive thinking is genuinely uplifting. Take the case of Michael Oher, one of life's losers if ever there was one, a shambling, largely illiterate black kid from the bad side of Memphis whose story is told in the current hit movie The Blind Side.

By a stroke of fortune, he is taken in by a rich white couple, Leigh Anne and Sean Tuohy. At high school, Oher's size and build seem to give him potential as a football player, but he still gets shoved around. Only when Leigh Anne (played by Sandra Bullock) runs on to the field to deliver a motivational speech to her charge does the ineffectual gentle giant become a tornado of the gridiron, who goes on to stardom in the NFL. The lesson is simple. Take things in hand, and Hollywood endings need not be fiction.

Increasingly, as Ehrenreich notes, positive thinking comes in religious packaging, in the modern mega-churches where "prosperity pastors" push their brand of motivational Christianity. "Close your eyes and see green" was the message of a particularly flamboyant specimen of the breed, Frederick Joseph Eikerenkoetter (or "Reverend Ike" as he was better known), who died earlier this year.

The vision he pushed, of "money up to your armpits", was not exactly biblical orthodoxy: "a roomful of money," he told his congregations and millions more who watched and listened on TV and radio, "and there you are, just tossing around in it like a swimming pool." He referred to his doctrine as "Thinkonomics" or "positive self-image psychology".

Needless to say, Reverend Ike died a rich man – and why not? Everyone is entitled to the good things in life. One of the most constant pitches in American advertising is "you deserve ..." – be it fine clothes or a splendid home. No wonder the credit card industry and salesmen of sub-prime mortgages have made such fortunes.

Such a vision admits no pessimism. At this week's jobs summit, for example, Obama waxed lyrical about the unmatched inventiveness, hard work and efficiency of the American worker, notwithstanding the parlous state of the national economy. Boosterism in turn can spill over into that favourite conservative doctrine of American exceptionalism. Few US presidents fail to remind audiences that they belong to "the greatest nation on earth".

But is it genuine optimism, or merely a way to avoid total despair? "Life's a piece of shit/When you look at it," runs another line from the Monty Python ditty. Unemployment may be at 10 per cent – but being laid off, according to positive thinking, is a terrific opportunity to rebuild your life. In another new movie here, Up in the Air, George Clooney plays a business traveller whose job is to sack people. He calls himself a "career transition counsellor". Ehrenreich cites her own experience of coping with breast cancer, where "cuteness and sentimentality" were the order of the day during treatment, and the correct attitude for patients was "upbeat and even eagerly acquisitive". Or take the cyclist Lance Armstrong, on record as saying that "cancer was the best thing that ever happened to me".

In theory, the current economic slump, a massive wake up call to the country, should put positive thinking to its greatest test. But the mindset will surely survive. During the Great Depression, one of the bestsellers of the era was Think and Grow Rich by Napoleon Hill, who also served as an adviser to President Franklin D Roosevelt. More than 70 years on, the book is still very much in print.