Sorry, but you can't have a baby: there's no room left

'There's one of them round our way even been given a furry tortoise! For free! We're mugs we are'

"We can't take any more of them, the country's full up as it is," someone screamed in the pub this week, referring to asylum seekers. It's a quaint idea, that Britain is like a night-club and there's only so many allowed in at a time, maybe due to fire regulations. And a couple of stern bouncers with shaved heads and ear-studs carry out instructions to let no one else in until there's been a cremation somewhere, to make room.

"We can't take any more of them, the country's full up as it is," someone screamed in the pub this week, referring to asylum seekers. It's a quaint idea, that Britain is like a night-club and there's only so many allowed in at a time, maybe due to fire regulations. And a couple of stern bouncers with shaved heads and ear-studs carry out instructions to let no one else in until there's been a cremation somewhere, to make room.

Let's hope there's not a report that forces Britain to become an all-seater country, as that could reduce the capacity by 15 million.

At what point does Britain have "as many people as it can take"? If the asylum seekers have tipped the balance, then we were fine at 56 million, but try to fit in 56 million and 50,000 and - wooooah - that last bit has sent the whole thing tumbling.

The basic mistake of the argument is that it only sees one half of human beings' social role, accepting that we consume but forgetting that we contribute. Otherwise, when there were only about one million people on the entire planet, they would all have been rolling in it. Life in the time of the ancient Sumerian civilisation must have been one long stress-free bank holiday, where you could always get a seat on a train, even in the rush-hour.

In the 18th century, when Britain's population was one quarter of its current tally, London must have seemed like a constant visit to an old aunt, with everyone offering you piles of sandwiches and cakes, saying "go on dear, someone's got to eat it. There's only 14 million of us, so get it down you. There's a whole cow to get through yet".

Similarly, the most densely populated part of the world today is Manhattan. So they should all be famished. But anyone who's ever been there knows it's a constant battle not to stuff your face 24 hours a day. Ask for a cheese sandwich and you're taken into a room with a loaf of bread in each corner, with a wheelbarrow full of cheese decorated in 30 different pickles and a roasted goat.

Whereas one of the poorest countries in the world, with regular famines, is Bolivia, in which there are five inhabitants per square kilometre. One of the richest, with no famine, is Holland, in which there are 326 people per square kilometre. More people means more potential wealth, because most people contribute more than they consume.

The main obstacle to that wealth being realised comes when those people are denied the right to take part in doing so. For example, farmers in Kent are currently complaining that tons of strawberries are rotting in fields because of a shortage of people willing to pick the things. This is the same Kent which, we are told, "can't take any more of them, we're full up as it is".

This is why most people find economics so confusing. If the problem involves a field of desperately unpicked strawberries and a group of people desperate for work, some might suggest the solution is for the potential workers to pick the strawberries. But they'd be stupid. Because the correct answer is to bring in a rule that the foreigners aren't allowed to work or earn money, send them back to Romania to get a hiding and put up the price of strawberries as there's a shortage.

But the prize goes to the Irish. There is now a concerted campaign against asylum seekers on the grounds that "the country's full up" - in Ireland. This is the one country whose population is roughly the same as it was 150 years ago. So it's a good job they had a potato famine or by now they'd be falling into the Atlantic. And the Irish are everywhere. In the remotest part of Borneo there's probably an Irish bar boasting the "finest Guinness in the jungle". When Ranulph Fiennes is traipsing across the Antarctic he probably stops off at a Molly O'Leary's bar. When he leaves they'd whisper "I hope he doesn't keep coming out here, there's barely any room left."

If the opponents of asylum-seekers were consistent in their complaints against extra people arriving, their main campaign would be against new-born babies - "we can't take any more of them. We feed them, give them nappies, there's one of them round our way even been given a furry tortoise! For free! We're mugs we are. It's no wonder the Japs are laughing at us."

But the abuse and slander goes on, rules become even tighter, and the Prime Minister declares the importance of being seen to be "tough" on the issue. So this week women are likely to be sent back to Afghanistan to the jolly greetings of the Taliban. Though I do see how Ann Widdecombe would find it especially difficult to have sympathy with those women. Because when they say, "But in our country it is demanded that we wear a veil at all times," Widdecombe could reply, "So what? Everywhere I go, people demand the same thing."