Why can't humans believe contradictions?

If you haven't already done so, nothing will further clarify your understanding of politics, literature, religion, and in short human beings, than to free yourself from the unsupportable notion that the human mind has any problem sustaining contradictions.

EDIT: If you happen to live in the US, I especially recommend considering this experiment, 2014 being an "election year".

EDIT: To downvoter, I understand that this sounds pretentious, and maybe is also OT. But I am in earnest. On HN we spend a lot of time pointing out logical fallacies, and I love that. But in the world at large, I believe it is largely a wasted effort. The sooner we accept that we ourselves would not escape the notice of our own wtf-dar, the sooner we can get to the heart of the arguments worth having.