“What are the facts? Again and again and again – what are the facts? Shun wishful thinking, ignore divine revelation, forget what “the stars foretell,” avoid opinion, care not what the neighbors think, never mind the unguessable “verdict of history” – what are the facts, and to how many decimal places? You pilot always into an unknown future; facts are your single clue. Get the facts!”One of the tricks of the military planning cycle is to sort out difference between guessing an enemies "intentions" and assessing the facts of his capabilities.
Interesting notes on that topic here:
Especially that last sentence.
UPDATE: Hmmm. What about economic forecasts?