1) Question authority. No idea is true because someone says so, not even me. Think for yourself.
2) Question yourself. Don’t believe in something just because you want to. Believing something doesn’t make it so.
3) Test ideas by the evidence gained from evidence and from experiment. If a favoured idea fails a well-designed test, it’s wrong. Get over it.
4) Follow the evidence, wherever it leads. If you have no evidence, reserve judgement.
5) And perhaps the most important rule of all: remember you could be wrong.
- Neil deGrasse Tyson in Cosmos: a Spacetime Odyssey