Baloney Detection Kit

"What skeptical thinking boils down to is the means to construct, and to understand, a reasoned argument and — especially important — to recognize a fallacious or fraudulent argument. The question is not whether we like the conclusion that emerges out of a train of reasoning, but whether the conclusion follows from the premise or starting point and whether that premise is true" (Sagan, The Demon Haunted World: Science as a Candle in the Dark [1996], 210).

All page references below are to the first edition of The Demon Haunted World.

Sagan's Positive Precepts

1. "Wherever possible there must be independent confirmation of the facts" (210).

2. "Encourage substantive debate on the evidence by knowledgeable proponents of all points of view" (210).

3. "Spin more than one hypothesis" (210).

Avoid prejudice.

"Retrospective studies show that some jurors make up their minds very early — perhaps during opening arguments — and then retain the evidence that seems to support their initial impressions and reject the contrary evidence. The method of alternative working hypothesis is not running in their heads" (210, footnote to this tool).

4. "Try not to get overly attached to a hypothesis because it's yours" (210).

5. "Quantify" (211).

6. "If there's a chain of argument, every link in the chain must work (including the premise) — not just most of them."

7. "Occam's Razor: This convenient rule-of-thumb urges us when faced with two hypotheses that explain the data equally well to choose the simpler" (211).

8. "Always ask whether the hypothesis can be, at least in principle, falsified" (211).

9. "Control experiments are essential" (211).

10. "Variables must be separated" (211).

Errors to be Avoided

1. "Ad hominem — ...attacking the arguer and not the argument" (212).

2. "Argument from authority" (212).

3. "Argument from adverse consequences" (212).

4. "Appeal to ignorance — the claim that whatever has not been proved false must be true and vice versa" (213).

"Appeal to ignorance — the claim that whatever has not been proved false must be true and vice versa (e.g., There is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist — and there is intelligent life elsewhere in the Universe. Or: There may be seventy kazillion other worlds, but not one is known to have the moral advancement of Earth, so we're still central to the Universe.) This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence." (213)

5. "Special pleading" (213). Sagan does not define this fallacy. He just gives examples of it. Here is a good description:

"Description of Special Pleading Special Pleading is a fallacy in which a person applies standards, principles, rules, etc. to others while taking herself (or those she has a special interest in) to be exempt, without providing adequate justification for the exemption.

"This sort of "reasoning" has the following form:

1. Person A accepts standard(s) S and applies them to others in circumtance(s) C.

2. Person A is in circumstance(s) C.

3. Therefore A is exempt from S.

"The person committing Special Pleading is claiming that he is exempt from certain principles or standards yet he provides no good reason for his exemption. That this sort of reasoning is fallacious is shown by the following extreme example:

1. Barbara accepts that all murderers should be punished for their crimes.

2. Although she murdered Bill, Barbara claims she is an exception because she really would not like going to prison.

3. Therefore, the standard of punishing murderers should not be applied to her.

"This is obviously a blatant case of special pleading. Since no one likes going to prison, this cannot justify the claim that Barbara alone should be exempt from punishment.

"From a philosophic standpoint, the fallacy of Special Pleading is violating a well accepted principle, namely the Principle of Relevant Difference. According to this principle, two people can be treated differently if and only if there is a relevant difference between them. This principle is a reasonable one. After all, it would not be particularly rational to treat two people differently when there is no relevant difference between them. As an extreme case, it would be very odd for a parent to insist on making one child wear size 5 shoes and the other wear size 7 shoes when the children are both size 5."

6. "Begging the question, also called assuming the answer" (213).

7. "Observational selection, also called the enumeration of favorable circumstances, or as the philosopher Francis Bacon described it, counting the hits and forgetting the misses" (213-14).

8. "Statistics of small numbers" (214).

9. "Misunderstanding the nature of statistics" (214).

Sagan just makes a joke here: "[A president he dislikes] expressed astonishment and alarm on discovering that fully half of all Americans have below average intelligence." Sagan gives no evidence that the president in question ever committed this fallacy. The joke has a thousand variations.

10. "Inconsistency" (214).

11. "Non sequitur — Latin for 'it doesn't follow'" (214).

12. "Post hoc, ergo propter hoc" — Latin for, 'It happened after, so it was caused by'" (215).

13. "Meaningless question" (215).

14. "Excluded middle, or false dichotomy — considering only the two extremes in a continuum of intermediate possibilities" (215).

This is a poor choice of names for this fallacy. Where there is no continuum and a statement is being compared to its opposite, the Principle of Excluded Middle is just an ordinary feature of orthodox logic. It would be a false dichotomy to say that we have only two choices. "Either all negatives are provable or none are." I defend the third alternative: some are provable and some are not.

15. "Short-term vs. long term" (215).

16. "Slippery slope" (215).

17. "Confusion of correlation and causation" (215).

18. "Straw man — caricaturing a position to make it easier to attack" (215).

This is a sloppy definition of what a "straw man" is. It is not just a caricature (emphasizing some features at the expense of others) but a complete misrepresentation. If someone attributes the wrong hypothesis to me ("Moleski thinks all negatives are provable"), then produces one example of an unprovable negative as a counterexample, they have not defeated my argument but just the "straw man" or "paper tiger" that they set up.

19. "Suppressed evidence, or half-truths" (216).

20. "Weasel words" (216). No definition given.

This is what I call "equivocation." There may be other variations that fall into this same category. It's not fair to change the meaning of words in the middle of a debate, so that the meaning of the words in the conclusion is different from the meaning in the statement of the question or the premisses.

One example of "weasel words" is to make a distinction without a difference.