According to a recent opinion poll, 18% of Americans think Barack Obama is a Muslim. This is not such a high figure really when you consider that in 1997 a CNN poll found that 37% of Americans thought extraterrestrials had been in touch with the US government. As far as I know nobody yet has done a poll to find out how many Americans think Obama is an extraterrestrial, but an educated guess would be about 20%. The US is probably the most polled nation in the world, and it does seem that at any given time, about one fifth of Americans – that's about 60 million people – are breathtakingly, jawdroppingly, fantastically ignorant.

Some of that ignorance has been manifesting itself in the ongoing debate over whether a mosque should be built near the World Trade Centre in New York. This is a sensitive topic, and it is obvious why it should be so, but as has been happening regularly in the US since Obama was elected president, many of the calmer voices, and the more reasoned arguments, have been overwhelmed by the idiocy of people who believe that the occupant of the White House is a non-American Muslim socialist. In years gone by such views would have been regarded as the lunatic ramblings of the intellectually challenged and paranoid, but they are becoming increasingly mainstream. Sarah Palin, the former vice-presidential candidate, for example, has questioned whether Obama was born in America despite the existence of a birth certificate that proves just that. It's no surprise that she has been at the forefront of the campaign to stop the mosque. So too have several politicians who have used the plan as an excuse to indulge in some pre-election Islamaphobia.

The proposed new building has become known as the Ground Zero mosque, although that, if you know your Dublin, is like calling Liberty Hall the GPO Tower. It will be almost three blocks away and you will not be able to see it from the World Trade Centre. It is being built by a moderate Muslim, who has repeatedly condemned the 11 September attacks and who has done work on several occasions for the FBI. He's no terrorist sympathiser. His building is not really a mosque, either. It will, according to the New Yorker magazine, contain one prayer room as well as classrooms, an auditorium, galleries, a restaurant, a swimming pool, a gym and a memorial to the victims of 9/11. It will be open to people of all faiths, and of none.

Such facts, of course, have not stopped some people from reacting as though Osama bin Laden will soon be spouting messages of hate every Friday from downtown Manhattan. Newt Gingrich, like Sarah Palin a possible Republican candidate for the presidency in two years' time, described the proposed new building as an "assertion of Islamic triumphalism" and part of an "Islamic cultural-political offensive designed to undermine and destroy our civilisation". Gingrich-inspired protestors can be seen in lower Manhattan every day brandishing placards about the importance of not handing Bin Laden a propaganda victory by building the mosque.

It would be a much bigger victory if permission to build the mosque was withdrawn and Bin Laden and his followers could portray America as hostile to Muslims on home soil, just as the invasion of Iraq and the war in Afghanistan are depicted as attacks on Muslims abroad. As New York's mayor Michael Bloomberg, one of the political heroes of this story, said, "part of being a New Yorker is living with your neighbours in mutual tolerance and respect. It was exactly that spirit of openness and acceptance that was attacked on 9/11".

A stronger argument for not building Park51, as the development is known, is that it is insensitive to people who had loved ones killed in the World Trade Centre. It is true that many of the bereaved have said they are against the building, but many too think it should go ahead. What about their feelings? Don't they get to be heard?

Another objection is that because of what happened on 11 September, the World Trade Centre has become one of America's sacred places and should therefore be protected from any controversy or taint. But long before 9/11, New York symbolised something else – the spirit of welcome and tolerance that Bloomberg alludes to. The city belongs to everyone, to its Catholics and Muslims, to its atheists and its Jews, its blacks and its whites. To suddenly exclude followers of Islam from that wonderful tolerance would be to change the very nature of a widely-loved city.

Ex-Pm's questions: let tony blair face tubridy:
With Tony Blair less than a week away from following in the footsteps of Coronation Street's Liz McDonald by appearing on the Late Late Show and then signing his book in Eason's, the campaign to have him barred from both studio and shop is getting more intense. The argument is that as Blair by most objective standards is a war criminal, Ryan Tubridy and Eason's shouldn't be facilitating his PR campaign for his book. I'm always uncomfortable with banning anybody from anything, especially where the exchange of ideas and arguments is concerned. Tubridy has already tweeted his reservations about Blair, so let us see what he makes of him on Friday. Then we can all not buy the book, which is a boycott certainly worth considering.