One speaker argued that economists should give up on prediction and settle for explanation, identifying where earthquakes might strike, if not when, and how they might be withstood, if not prevented.

ECONOMIST: Economics focus

In principle, in a free society, people (adults, at least) should not be prevented from doing something if it does not harm others.

ECONOMIST: Shopping for a drugs policy

While you may not see reductions statistically, you can't talk about crime that it has prevented if it's not on the books first.

NPR: Public Surveillance: Security vs. Privacy, Part 2

But Ms Thompson ruled against the application saying her "legal role is to ascertain how the men died" not if the deaths could have been prevented.

BBC: England

In the recent crisis over Iraq, Russia could not have prevented America from striking Iraq, if America had so decided.

ECONOMIST: Russia��s world

This, he says, could have been prevented if a well-connected business lobby had not illegally pushed the ship back into service when it still needed vital repairs.

ECONOMIST: Senegal

We must not allow children to die from this disease if it can be prevented.

BBC: Meningitis B vaccine gets European licence

Mr Salmond hit back saying the reasons for the BBC withdrawing the invitation were not petty and had to be confronted, asking if David Cameron would be prevented from appearing on Olympic coverage in London.

BBC: First minister's questions