The mad cow crisis has been described as an irrational, collective scare; a lethal epidemic with potential casualties in the thousands or hundreds of thousands; a criminal or quasi-criminal cover-up; an epitome of government negligence and bureaucratic incompetence; a tragic outcome of Conservative, laissez-faire policy and capitalist greed; as well as a pitiable failure of veterinary medicine and science. As the crisis unfolded, the only safe statement that could be made was that none of these characterizations was established but that none could be clearly and totally ruled out. The most striking feature of the crisis was that the risk involved could be assessed with no better accuracy than being within a range from zero to infinity.