Nice essay by sociologist Frank Furedi on worse-case thinking, exemplified by our reaction to the Icelandic volcano:

I am not a natural scientist, and I claim no authority to say anything of value about the risks posed by volcanic ash clouds to flying aircraft. However, as a sociologist interested in the process of decision-making, it is evident to me that the reluctance to lift the ban on air traffic in Europe is motivated by worst-case thinking rather than rigorous risk assessment. Risk assessment is based on an attempt to calculate the probability of different outcomes. Worst-case thinking ­ these days known as precautionary thinking’ — is based on an act of imagination. It imagines the worst-case scenario and then takes action on that basis. In the case of the Icelandic volcano, fears that particles in the ash cloud could cause aeroplane engines to shut down automatically mutated into a conclusion that this would happen. So it seems to me to be the fantasy of the worst-case scenario rather than risk assessment that underpins the current official ban on air traffic.

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Worst-case thinking encourages society to adopt fear as of one of the key principles around which the public, the government and various institutions should organise their lives. It institutionalises insecurity and fosters a mood of confusion and powerlessness. Through popularising the belief that worst cases are normal, it also encourages people to feel defenceless and vulnerable to a wide range of future threats. In all but name, it is an invitation to social paralysis. The eruption of a volcano in Iceland poses technical problems, for which responsible decision-makers should swiftly come up with sensible solutions. But instead, Europe has decided to turn a problem into a drama. In 50 years’ time, historians will be writing about our society’s reluctance to act when practical problems arose. It is no doubt difficult to face up to a natural disaster — but in this case it is the all-too-apparent manmade disaster brought on by indecision and a reluctance to engage with uncertainty that represents the real threat to our future.