I'm not sure if I've got my miserablist head round this exactly, but it seems that not only do pessimists generally have a much more realistic view of the world than optimists, but optimists maintain their unrealistic position by ignoring bad news. Tell someone that the 40 per cent chance they thought they had of getting cancer is actually 30 per cent and they'll revise their estimate to a realistic 31 per cent. Those who believed that their chances were just 10 per cent 'only marginally' increased their odds of getting the disease. MRI scans showed that the frontal lobes of the happy-go-lucky 80 per cent of the population just weren't letting any mopey facts change their upbeat, can-do, won't-die minds.

Chris Chambers, a neuroscientist from Cardiff University, told the BBC this is a 'cool' piece of research:

For me, this work highlights something that is becoming increasingly apparent in neuroscience, that a major part of brain function in decision-making is the testing of predictions against reality – in essence all people are 'scientists'. And despite how sophisticated these neural networks are, it is illuminating to see how the brain sometimes comes up with wrong and overly optimistic answers despite the evidence.

Illuminating maybe, but definitely worrying because if 80 per cent of the civilian population are bad scientists, as Chambers seems to suggest, then presumably 80 per cent of the actual scientist population are also bad scientists whose frontal lobes will want nothing to do with negative results or even the gloomier sort of theory. I think, pace Chambers, that the findings are not so much illuminating as catastrophic and that we must be very wary of cheery biologists, psychologists and physicists.

Yes, optimists may be happier and healthier than pessimists, but they are also more often wrong. No wonder pessimists are so pessimistic, we have to bear the burden of reality on ourselves while most people are diddling about in cloud-cuckoo land. Listen: there really is a financial problem, the planet is strangling, human beings are incorrigible and we're all going to die. No – listen, will you? – all of us. However, although I don't want to be too positive, there are two great advantages of pessimism: we hardly ever get taken by surprise and disappointment is an unknown emotion to the 20 per cent who know shit happens and that it actually happens to them.