What is more, to refute it Iraq seems to be obliged to prove a negative, which, to a layman, seems a little tricky.

ECONOMIST: Assessing the evidence against Saddam Hussein

His approach was harder to pull off: raise the bar, create a zone of privacy, don't fall into the trap of trying to prove a negative.

CNN: 'I've made mistakes...'

In years past Turkey's spotty democracy was often cited to prove a negative: the Turkish case (along with Indonesia's and Malaysia's, also with reservations) showed that Islam did not pose an insuperable barrier to multiparty democracy.

ECONOMIST: The Turkish model