A scene from “Unfinished Business”

How did we escape from the prison [of ignorance]? It was the work of generations of searchers who took five simple rules to heart. (1) Question authority. No idea is true just because someone says so, including me. Think for yourself. Question yourself. (2) Don't believe anything just because you want to. Believing something doesn't make it so. (3) Test ideas by the evidence gained from observation and experiment. If a favorite 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 judgment. And perhaps the most important rule of all: (5) Remember, you could be wrong.