Redefining truth in a 'post-fact society

What's a current example of people embracing an untruth? You wrote in The New York Times about the Barack-Obama-is-a-secret-Muslim rumour.

There is this persistent email rumour from anonymous people – it doesn't appear to have much organization behind it – going around to lots of people. The email says that Barack Obama basically has lied about his past, that he is not a Christian and that he's secretly a Muslim. There are a bunch of checking websites on the Internet and newspapers that have debunked this story and yet it persists. Psychologists have shown that debunking rumours sometimes helps them persist and can kind of amplify them.

One of the ideas here is that repetition helps us remember things, because when a fact is repeated to you, you become familiar with that fact, and over time you can even forget that you first heard the fact in the context of debunking. So, if someone tells you it's not true that Barack Obama Muslim, several days later you might not remember the "not" part of that.