# Questioning assumptions

With the explosion of information due to the Internet, we should be more wary of the trustworthiness of the source, and even the veracity of the information. I also tell you about the Barber Paradox and a brief explanation of “proof by contradiction”.

1. Jay Johnson

Proof by contradiction sounds a lot like confirmation bias. You think?

2. Vincent

Yes it does. In fact, that’s the point. The usual example used is proving that the square root of 2 is not a rational number. So we assume that the square root of 2 *is* a rational number, and at the end of a series of arguments, we get a contradiction. Hence, our original assumption must be wrong. So square root of 2 is *not* a rational number.

Personally, I feel like proof by contradiction is used when other methods of proving proves (pun not intended) to be lengthy or difficult. It’s like, “I don’t know how to prove the sun rises in the east.” So, “Let’s assume the sun doesn’t rise in the east!”.