But what we need is evidence. Not anonymous officials and unnamed intelligence sources and all the other comedians on the journalistic stage. Nor the dead whose numbers wobble by a difference of 100,000 bodies… Who are the killers? Who gave them the orders? And this means not just who gave the orders to the killers of Syria. It also means — do not mention here the kings and prince of the Gulf — that we must discover who is really behind Isis? And that, I suspect, is the question of this decade.