This is the question which people ask themselves before almost every presidential election: why, when the United States is teeming with brilliant and inspiring people, are its voters so often faced with a choice between two deeply unimpressive men? I would have thought the answer was pretty obvious: because deeply unimpressive men continue to be elected. This year, the American people have been instructed to elect one again. Almost every powerful progressive voice has told them not to vote for the progressive candidate, but to vote instead for The Man Who Isn't There. Ralph Nader may stand for everything the Guardian, the Nation magazine, even Noam Chomsky, claim to support, but all these voices - indeed just about everyone on the left - have been urging the voters in swing states to choose John Kerry.  Their argument, of course, is that Kerry is the only candidate who can knock George Bush off his perch. He might be about as inspiring as a parking lot on a wet Sunday in Detroit, but his vacuity is better than the president's aggressive certainties. The contest is so close that if even a few thousand people vote for Nader rather than Kerry in the swing states, it could win the election for Bush. This is why Republicans have been giving money to Nader. So Americans should vote for the Democrats in 2004, and worry about the wider failings of the US political system when the current president is safely out of the way.  And their argument has merit. Bush has already launched two unnecessary wars, threatened 40 or 50 nations with armed aggression, ripped up international treaties and domestic regulations, granted corporations a licence to cook the planet, waged a global war against civil liberties and sought to bury that old-fashioned notion that the state should tax the rich and help the poor. The world would certainly be a safer and a better place without him.  As a result, a Guardian leader told us last week, these are "exceptional circumstances Mr Kerry's flaws and limitations are evident; but they are put in the shade by the neo-conservative agenda and catastrophic war-making of Mr Bush". In an open letter to Ralph Nader in January, the Nation magazine claimed: "This is the wrong year for you to run: 2004 is not 2000. George W Bush has led us into an illegal pre-emptive war, and his defeat is critical."  The problem with this argument is that both publications said the same thing about the 2000 elections. The Nation's columnist Eric Alterman blames Al Gore's defeat on Nader's "megalomania". Three days before the vote, the Guardian argued that "... the marginalised Mr Nader cannot win ... Exciting [Al Gore] ain't. A visionary he is not. But he is the safe, wise choice."  And similar warnings have been issued during almost every presidential election in modern times. Under the US   electoral system, which is constructed around patronage, corruption and fear of the media, there will always be exceptional circumstances, because it will always throw up dreadful candidates. Only when the Americans choose a man or woman who is prepared to turn the system upside down and reintroduce democracy to the greatest democracy on earth will these exceptional circumstances come to an end. In choosing the bad rather than the terrible in 2004, in other words, Americans will be voting for a similar choice in 2008. Whereupon they will again be told that they'd better vote for the bad, in case the terrible gets in.  Any president who seeks to change this system requires tremendous political courage. He needs to take on the corporations which have bought the elections, and challenge the newspapers and television stations which set the limits of political debate. Kerry, who demonstrated plenty of courage in Vietnam, has shown none whatsoever on the presidential stump. Last week, when the Republicans were questioning his commitment to defence, he announced that "even knowing what we now know" he would have voted to give President Bush the authority to attack Iraq.  Ten days ago his national security adviser James Rubin told the Washington Post that if Kerry was president he would "in all probability" have launched a military attack against Iraq by now.   Kerry's ability to raise almost as much money as the Republicans is seen as a triumph for American democracy; but his corporate backers are funding him not because they believe in democracy, but because they believe that he will do what they want. And they are unlikely to be wrong. When Kerry gets his orders, he reports for duty.  The idea that this frightened, flinching man would oversee the necessary democratic revolution is preposterous. He has made the system work for him by working for the system. He knows that as soon as he turns against it, it will destroy him. What else does he have to fall back on? Charisma? Popular enthusiasm? He's no Hugo Chvez. A vote for Kerry is not just a vote against George Bush. It is a vote for the survival of the system which made Bush happen.  I'm not an unhesitating fan of Ralph Nader's - I believe that some of his positions on trade, for example, are wrong - but no one could deny that he possesses courage. His decision to stand in November, when even his former supporters are telling him not to, is as brave as it is foolhardy. He has spent his working life fighting the corporations and being attacked in the media. This month he did something no other US politician has dared to do, and took on the Anti-Defamation League, the organisation which smears opponents of Israeli policy as anti-semites.  He won't be elected in November, of course, but that's not the point. The point is that if you want to change a system, you have to start now, rather than in some endlessly deferred future. And the better Nader does, the faster the campaign for change will grow.  The Nation claims that Nader would have "a far more productive impact" as "a public citizen fighting for open debates and rallying voters to support progressive Democrats". But what possible incentive would the Democrats have to listen to him? He has influence over these cowering creatures only while they are afraid that he might take their votes.  None of this is to suggest that there is no difference between Kerry and Bush. Where Bush is active, Kerry is passive. He wants to maintain massive levels of defence spending, but, despite his efforts to assure the media that he is as mad as Bush, he would probably be more reluctant to attack other nations. He wants to cut taxes, but he is less willing to wage war on health and education. He wants to hold down the price of oil, but doesn't want to help the corporations open up the Arctic Wildlife Refuge.  The question is whether this difference is sufficient to justify the abandonment of the only current electoral attempt to democratise the US political system. I don't believe it is. Progressives on both sides of the Atlantic are asking American voters to sacrifice liberty for security, and democracy for expediency. The voters should ignore them.