For CJD as the cliche has it was a disaster waiting to happen and we have all

For CJD, as the cliche has it, was a disaster waiting to happen, and we have all helped to bring it about. Children are at far greater risk from traffic, men from heart disease and women from breast cancer. Perhaps CJD in the end will prove to be like rabies; an exceedingly nasty, understandably exciting horror, but rare. In short, if CJD was simply one of those things - a bolt from the blue, like Hong Kong 'flu - then we could reasonably say, "c'est la vie", and set out to minimise the damage with fitting stoicism That is what the Government and farmers would like us to do. However unpleasant CJD becomes, it is likely (not certain, but likely) to be low on the catalogue of life's hazards. We meanwhile can reflect that prions are an unknown; and that many more people have eaten beef than have risked HIV infection. There is one sense in which we should not be too carried away.

So is it more charitable to suppose that the Government believed its own propaganda, or that it did not? Moral philosophers might like to ponder this John Selwyn Gummer presumably did believe it. But there's an ancient adage from the philosophy of science that squashes that argument entirely: "Absence of evidence is not evidence of absence!" Of course, we should always strive to be charitable. The Government has sought to quiet all fears these past five years with the all-dismissive plea, "there is no evidence!". The agent of Bovine Spongiform Encephalopathy - an invasive unchaperoned protein known as a "prion", more like a computer virus than an ordinary virus - is a biological novelty. It is virtually unknown outside the little coterie of neurological diseases with which it is associated: scrapie in sheep, BSE in cattle, kuru and CJD in humans.

Biology is not physics; no one can ever say, a priori, what a virtually unknown agent might or might not do. Living organisms - or in the case of a prion, sub-living organisms - are always one step ahead of us; even the ones we think we know about. This government has already robbed them of their jobs and the value of their houses They are not going to allow it to poison them as well.. SOME have suggested that Creutzfeldt-Jakob Disease may be as threatening as HIV and of those who cry "Nonsense!" we might reasonably ask, "Well, why should it not?". The risks of eating beef, ministers try desperately to tell us, are lower than they have been for a decade They are very probably right, but nobody believes them.

The public have made another risk assessment for themselves: the chances of a minister telling lies, or at least half-truths, are very high. Yet Douglas Hogg, the Minister of Agriculture, repeats his assurance that he is "eating beef with confidence". What is this supposed to mean? Does he eat it with the same confidence as he eats a garden lettuce? No doubt Mr Hogg crosses the road with confidence but he would be a fool if he failed to look both ways before doing so.Politicians hate to admit ignorance or uncertainty They must always seem to be in control. The public must never be "alarmed" except over what the opposing political parties might do.

But because they tried to reassure at a time when they should have been gently preparing for the worst, the Tories are in bigger trouble than ever Almost nothing they do will now allay public alarm. Nobody can be certain the controls on the removal of offal from carcasses are always observed; nobody can be completely certain that it is safe to eat even prime beef. Even now, nobody can quantify the risks of eating beef or beef products. Ministers said that the risk of the disease crossing the species barrier to humans was insignificant Wrong. It was unquantifiable and there is a world of difference between those two words.