Logical fallacies and their use in skepticism
From WikiSynergy
Though there is overlap, skeptics and proponents generally use different sets of fallacies. For example the Psychologist's fallacy in which an observer assumes he is objective, is not used as much by skeptics as by proponents— since those who see usually believe. Special pleading is another such example.
The problem with breaking down texts into logical fallacies is that usually several fallacies are presented per paragraph of text. Also, they tend to build up and combine with other errors till the skeptic has achieved an impenetrable cloud, often topped by the cherry of ad hominem derision. It can nevertheless be useful to analyze skeptical offerings deeply.
[edit] Accident
An exception to a (generally valid) generalization is ignored.
- Anecdotal evidence is not scientific proof.
- All evidence for near-death experiences is anecdotal.
- Therefore near-death experiences are not proven to occur.[1]
This fallacy is often used for anecdotal evidence. It is generally true that, for example, a single anecdote from a single person, is not good scientific evidence; and it is true that many anecdotes from people who have influenced each other may be lousy evidence. But there is nothing unscientific about anecdotal evidence, if it is properly handled by the investigating party. Memories which have been cross-checked and otherwise vetted can constitute reliable evidence. This error is often combined with an unwillingness to consider evidence in probabilistic terms.
[edit] Affirming a disjunct
- A and/or B
- A
- Therefore, it is not the case that B
- A and/or B
- B
- Therefore, it is not the case that A
Use in skepticism:
- The mind is separate from the brain or the mind is generated by the brain
- The mind is generated by the brain
- Therefore the mind is not separate from the brain
This is often combined with a misuse of Occam's razor; remember that an hypothesis must account for all the valid data.
[edit] Ad nauseum
"Ad nauseum" fallacies are the repetition of a single argument -or assertion- while excluding all other data. Other data and reasoning is intentionally ignored.
Example: in a debate with a skeptic, nearly any statement starting off with "there is no evidence" will be an argument ad nauseum. There is almost always evidence, and usually the only valid question is what that data indicates and what conclusions one can draw from it. (See also SCEPCOP:There is no hard evidence.)
[edit] Appeal to motive
challenging a thesis by calling into question the motives of its proposer
[edit] Argument from ignorance
Claiming that a premise is true because it has not been proven false, or false because it has not been proven true.
This is the overarching fallacy of pseudoskepticism. However, it is usually occurs as an unstated assumption, underlying other arguments presented. Often it is used in the disguise of Occam's razor, or the maxim "Extraordinary claims require extraordinary evidence." The claim is seldom made that "X is false because there is no proof," or "current understanding is true because it has not been proven false," but the claim is implicit in cases of unscientific bias or refusal to accept good evidence.
[edit] Burden of proof
it is always possible to seek to discredit an idea by suggesting that the Burden of Proof should be set to an inappropriately high level. http://en.wikipedia.org/wiki/Burden_of_proof_%28logical_fallacy%29
[edit] Cherry picking
Part of other fallacies.
[edit] Circular cause and consequence
The consequence of the phenomenon is claimed to be its root cause.
[edit] Composition
Fraud. something is true of the whole from the fact that it is true of some part of the whole
[edit] Correlation proves causation
the correlation of two events are claimed to have a cause-and-effect relationship when none has been demonstrated. For example astrology claims that correlations between personality and star charts means that the stars cause the personality to be a certain way. Skeptics claim that correlation between brain states and consciousness means that the brain produces consciousness.
[edit] Division
Fraud, error something true of a thing must also be true of all or some of its parts.
[edit] Judgmental language
[edit] Loki's Wager
A Loki's wager fallacy occurs when it is impossible to describe when one state shades over into another, and therefore an arguer insists that no conclusion should be reached. This occurs in skepticism in matters of evidence: when is proof sufficient? A pseudoskeptic will insist that there is insufficient proof when there is, yet he cannot be proven wrong. Frequently combined with Moving the goalposts.
[edit] Moving the goalposts
Also known as raising the bar. Evidence presented in response to a specific claim or request for proof is dismissed and some other (often greater) evidence is demanded. This attempts to leave the impression that an argument had a fair hearing while actually reaching a preordained conclusion.
[edit] Proof of impossibility
This is not a logical fallacy (proofs of impossibility can exist logically), but it is scientifically impossible. It is commonly used in skepticism as the proposition that "it is against the laws of physics so it is impossible." Usually the assertion that it is "against the laws of physics" is false, and also a unsubstantiated positive claim.
[edit] Reification
[edit] Straw man
Misrepresenting the position of an opponent.
Example: "...it is very easy for me to prove that a god or a soul cannot exist, but it would be virtually impossible for anyone to prove that a god or a soul does exist (if only because of the impossibility of differentiating natural v hypothesized non-natural effects)"[2]
In this example, the skeptic assumes that someone has claimed that the soul is a non-natural effect. See also Argument from ignorance (Proving a negative) and Pseudoskepticism#3.
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