Important Principles of Critical Thinking

1. Just saying something doesn't make it true.
2. All assertions, statements, hypotheses, theories, and claims should be considered uncertain.
3. The confidence with which a belief is held should be proportional to the logic and evidence supporting it, rather than how it makes you feel.
4. Faith should only be used to the extent that supporting evidence and logic cannot be found.
5. Extraordinary claims require extraordinary evidence.
6. Empirical evidence trumps everything else.
7. Of two explanations, hypotheses, theories, or statements, the one deemed most unlikely has the burden of proof. If the likelihood cannot be determined, the viewpoint that goes against what a majority of informed people believe has the burden of proof.
8. Of two explanations that explain equally well, the more probable is preferred.
9. Of two explanations that explain equally well, the one that explains the most with the fewest principles or assumptions is preferred (Principle of Parsimony).
10. An extraordinary claim is one that contradicts natural law or for which no reasonable mechanism can be proposed; or whose frequency is extremely rare.
11. An extraordinary claim always has the burden of proof.
12. Supernatural claims are extraordinary claims.
13. Arguing that something is true because everyone believes it is not valid.
14. When asked to explain an extraordinary event, the first response should always be whether it actually occurred.
15. Anything in an explanation that does not contribute to better understanding should be eliminated (Occam's Razor).
16. Most things aren't black-and-white, but partly true.
17. Pay attention to the implications of a belief. If someone could really predict the future or read minds, how much money would they have?
18. Remember that people don't have to be lying to say something that isn't true. They can be mistaken, misremember, misperceive, operating under false assumptions, forget, and so on.
19. Examine what else must be true if a claim is true. If it’s true that psychics can solve criminal cases, why are there still unsolved crimes?
20. Ask whether claims make sense. Hardly a day goes by that someone, somewhere, doesn’t thank God for sparing their life in a horrible accident. If God was really taking care of them, wouldn’t he have prevented the accident in the first place?
21. Determine if there’s anything internally inconsistent or illogical in a position. Take astrology for instance: If heavenly bodies can influence our lives, and their size and distance makes no difference, how could the effects of all the trillions and trillions of stars, planets, asteroids, comets, moons, and so on, be accounted for in a horoscope?
22. The less you know about something, the less confident you should be in your conclusions. Even though logically things may seem a certain way, if you don’t know much about the subject, proceed cautiously — preface your statements with "I could be wrong, but. . . This can save you a lot of embarrassment later on. (Personal experience!)