Just by having a thought, he convinced himself that it was true

That's how Whatever It Is, I'm Against It described the following nugget from Rumsfeld:

I’m going to speculate here that a non-trivial portion of his finances and his recruits come from outside the country. And they undoubtedly come through Syria, and they come through Iran, probably, and through other countries

That politicians do this is nothing special. But that this is the exact same way the mainstream media nowadays acquires the facts for its 'fact-checking' is more serious matter.