Senator John McCain's choice of a running-mate was always going to be crucially important. He is 72 years old and has had episodes of skin cancer. From a medical and actuarial point of view, there must be a significant risk that he will not live to complete his first term as president, if elected. Whichever contender he chose for the vice-presidential nomination was bound to be scrutinised as having a real possibility of becoming the next president by right of succession.

Nobody is assuming that Senator Joe Biden will succeed Barack Obama; he is 18 years older - though there is an assassination risk. Yet all American voters in November will be conscious that a vote for the McCain-Palin ticket could put Governor Sarah Palin into the White House. Will the voters see her as adequate for that role? That is the measure of the risk that John McCain is taking. He is staking his whole campaign on the ability of a young woman whom he had met only once to convince the American people she could handle the jobs of commander-in-chief and president of the United States. She has precisely 65 days in which to do it, starting from last Thursday. That is a tall order.

The obvious argument against the idea of a Palin presidency is her inexperience. This argument is blunted because it has already been used against Barack Obama, both by Hillary Clinton and by the Republicans. In fact, most American presidents come to office without adequate previous experience. Indeed, one could say that there is no sufficient experience for the presidency, except by having been president before, and the Constitution forbids a third term.

Of the last five presidents, the older George Bush was a long-term Washington insider, and Ronald Reagan had been Governor of a big state, California, but Jimmy Carter, Bill Clinton and the younger Bush had little experience of international affairs or indeed of large-scale administration. The Governor of Texas does not have the powers of the Governor of California. If one substitutes Alaska for Arkansas, Sarah Palin is about as well qualified for the presidency in terms of experience as Bill Clinton in 1992.

Fortunately, there is no reason to think that John McCain's decease, even if, sadly, it should occur, is at all imminent. Given a couple of years as vice-president, Governor Palin could expect to meet most of the world's leaders. She would then have a wider international network than Senator Obama enjoys at present. The question that ought to be asked is not whether she has the experience, but whether she has the character and judgment.

There are some strong points in her record. She has an 80 per cent approval rating as Governor. I doubt whether there are at present any other governors in the United States whose ratings are even close to hers. Alaska is an oil state, with reserves almost as important as those of Canada. Governor Palin believes that Alaskan oil should be developed. That is already one of the central issues of energy policy, and she has developed her own position. That is not the action of a lightweight.

I'm afraid that a lot of sophisticated people will sneer at Governor Palin. She will get some of the backlash that women politicians have to expect. The men who talked down Hillary Clinton will talk down Sarah Palin as well. That goes with gender politics. On the other hand, some women, including some of the 18 million who voted for Hillary, will vote for Sarah, simply because she is a woman who might become the first woman president.

European visitors to the United States are mostly exposed to the East Coast culture; many Americans live wholly inside that culture. It is a culture of modernism, in no way to be despised, but it is not the only culture in America.

The view of the world from Harvard Yard is very different from the view from those states that Europeans seldom visit, and do not really understand. These are the states that have retained much of the religion, the practicality and the moral values of the frontier. In those states there is a conservative majority, based on the Bible, the Family and the Flag.

Senator McCain has found a running-mate who is not a neocon, which is a subtype of Washington intellectual, but a genuine conservative. The Reagan majorities in the elections of 1980 and 1984 were built on such conservative voters; many would still describe themselves as “Reagan Republicans”.

Governor Palin believes in honest government and cutting waste; she does not believe in gay marriages, she supports the “right to life” rather than the “right to choose”. She herself is raising a Down's syndrome child, having refused the abortion that would have been available. She is even a Darwin-sceptic and supports the teaching of creationism. She is a Pentecostalist, an unfashionable Church without the cachet of the black churches. She is no racist; her own children have Inuit blood. She calls herself a “hockey mom”; like Margaret Thatcher, she seems to combine basic conservative simplicities with a will of iron.

Most of her beliefs are regarded as obscurantist by modern America. Yet one should remember that there are more “hockey moms” in the United States than there are Harvard graduates. The cultural elite on the two coasts is highly significant; it dominates in the media, in academia and usually in politics. Yet conservatives can win elections because there are so many of them. They are the voters of the heartland, whom New Yorkers fly over on their way to Los Angeles.

At the end of the Democratic convention, it looked as though Senator Obama was bound to win. I still expect him to do so. Governor Palin is a high-risk choice, but Senator McCain has always been willing to take high risks. That is the privilege of the fighting soldier and of the political underdog.

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