Philip Dick has a famous quote about reality. Actually on the web you can find two versions of the quote:
Reality is that which, when you stop believing in it, doesn’t go away.
Reality is whatever refuses to go away when I stop believing in it.
If the second quote is correct, well Philip Dick died in 1982, and yet reality certainly exists, so Philip Dick must not have died in 1982. So I decided to stop believing in the second quote. And yet the second quote remains.