Yes, they all make one or several of the following mistakes:
1. Theory Influences Observations — When you have a theory of something, you interpret the results inside your theory. So when Columbus arrived in the New World, he saw Asian spices and roots. His theory said he should be in Asia.
2. The Observer Changes the Observed — The act of studying an event can change it. This can happen with anthropologists studying tribes to physicists studying electrons. This is why psychologists use blind and double-blind controls. Science tries to minimize this, pseudoscience does not.
3. Equipment Constructs Results — The equipment used often determines the results. The size of the telescope shaped and reshaped the size of the universe. The kind of fish net determines what fish it can catch.
4. Anecdotes != Science — Stories that people pass on is not the same as controlled experiments. Pseudoscience points to anecdotes; science points to reputable studies.
5. Scientific Language Doesn’t Make It Scientific — Dressing up a belief in scientific language doesn’t make it science. This is easily seen with “creation science” and New Age pseudoscientific mumbo-jumbo.
6. Bold Statements Do Not Make Claims True — L. Ron Hubbard called Dianetics “a milestone for man comparable to his discovery of fire and superior to his invention of the wheel and the arch.” But it wasn’t. The more extraordinary the claim, the more extraordinary well-tested the evidence must be.
7. Heresy Does Not Equal Correctness — Copernicus and Galileo and the Wright Brothers were rebels. But just because someone is a rebel doesn’t make them right. Holocaust deniers are rebels, but they need historical evidence for their position. It’s heresy to say Bush planned the 9/11 attack, but that isn’t evidence of the government suppressing the truth.
8. Burden of Proof — The person making the extraordinary claim has the burden of proving their claim is true and better than the commonly accepted position. If a man claims he moved a mountain with his mind, the burden of proof is on him.
9. Rumors Do Not Equal Reality — Rumors begin with “I read somewhere that…” or “I heard from someone that….” Before long, the rumor becomes reality, as “I know that…” passes from person to person. These stories are often false. For instance, everyone knows George Washington chopped down a cherry tree and couldn’t lie about it. He also had wooden teeth. Both stories are false.
10. Unexplained Is Not Inexplicable — Just because you can’t explain something doesn’t mean it can’t be explained. Firewalking seems inexplicable, but once you know the explanation it seems obvious. The same goes for all magic tricks. And even if an expert can’t explain it doesn’t mean it can’t be explained someday. Think of how many things — from germs to atoms to evolution — couldn’t be explained two hundred years ago!
11. Failures Are Rationalized — Scientists acknowledge failures and reformulate theories. Pseudoscientists ignore or rationalize failures.
12. After-the-Fact Reasoning — Also known as, “post hoc, ergo propter hoc,” literally, “after this, therefore because of this.” It’s superstition. Because I carried a rabbit’s foot, I sold more products today. Because I have blonde hair, I’m ditzy. Because I used a dowsing stick, I struck water. All superstition. Correlation does not mean causation.
13. Coincidence — Most people have a very poor understanding of the law of probability. Say you are about to make a call and as your hand touches the phone they call you. How could that be a coincidence? It must be ESP. We forget about the other thousand times we call someone and they don’t call us first. You make 5 baskets in a row, and you’re “on fire.” But statistically your chances are the same as a coin-flip. The human mind looks for patterns and often finds them when there are none.
14. Representativeness — Something may seem unusual when it’s not. Baselines must be established. For instance, tapping and scratching sounds in your house may be ghosts, but it’s probably just pipes and rats. Many ships are lost at the Bermuda Triangle, but only because there are more shipping lanes there than in surrounding areas. When that is factored in, the accident rate is actually lower in the Bermuda Triangle.
15. Emotive Words and False Analogies — Loaded language can be used to provoke emotion and obscure rationality. Industry can be called “raping the environment” or abortion “murdering innocent children” or a political opponent a “communist.” Rarely does this further rational thought, but clouds the issue with emotion and rhetoric.
16. Appeal to Ignorance — This claims if you can’t disprove something, it must be true. So if you can’t disprove psychic power or ESP or ghosts, they must be real. The problem is you can’t disprove Santa Claus or the Tooth Fairy, either. Belief should come from positive evidence in support of a claim, not a lack of evidence.
17. Attacking the man —Redirect the focus from thinking about the idea to thinking about the person holding the idea. Calling Darwin a racist or a politician a communist or past figure a slaveholder does not discredit their ideas.
18. Hasty Generalization — Also known as prejudice, or drawing conclusions before the facts warrant. A couple of bad teachers and it’s a bad school. A couple of bad cars and that brand of automobile is unreliable.
19. Overreliance on Authorities — We must be careful not to accept a wrong idea from someone we respect, nor write off a good idea because of a supporter we disrespect. Examining the evidence ourselves helps us avoid these errors.
20. Either-Or — This is the argument that when one position is wrong, another must be accepted. For instance, creationists spend much of their time attacking evolution because they think if evolution is wrong, then creationism must be right. But for a theory to be accepted, it must be superior to the old theory. A new theory needs evidence in favor of it, not just against the opposition.
21. Circular Reasoning — Also known as begging the question, this is when the conclusion or claim is merely a restatement of one of the premises. For instance in religion: Is there a God? Yes. How do you know? Because my holy book says so. How do you know your holy book is correct? Because it was inspired by God. Or in science: What is gravity? The tendency for objects to be attracted to one another. Why are objects attracted to one another? Gravity. While these definitions can at times be useful, we need to try and construct operational definitions that can be tested, falsified, and refuted.
22. Reductio ad Absurdum and the Slippery Slope — Reductio ad absurdum is the refutation of an argument by carrying the argument to its logical end and so reducing it to absurd conclusion. For instance: Eating ice cream will cause you to gain weight. Gaining weight makes you overweight. Overweight people die of heart disease. Thus eating ice cream leads to death. A creationist might argue: Evolution doesn’t need God. If you don’t need God, you reject him. Without God, there is no morality. Therefore, people who believe in evolution reject God and have no morals.
23. Effort Inadequacies and the Need for Certainty, Control, and Simplicity — Most of us want certainty, want to control our environment, and want nice, neat simple explanations. But it doesn’t always work like that. Solutions are sometimes simple, but other times they are complex. We must be willing to make an effort to understand complex theories instead of rejecting them out of laziness.
24. Problem-Solving Inadequacies — When solving problems, we often form a hypothesis and then look only for examples to confirm it. When our hypothesis is wrong, we are slow to change our hypothesis. We also gravitate towards simple solutions even when they don’t explain everything.
25. Ideological Immunity — We all resist changing fundamental beliefs. We build up “immunity” against new ideas that do not fit within our paradigm. The higher the intelligence, the greater the potential for ideological immunity. This can be the greatest barrier to changing our weird beliefs.
(Source: Michael Shermer)