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Carl Sagan's
Logical and Rhetorical Fallacies
In Sagan's classic book, "The Demon Haunted World," he presents a "baloney detection kit"
which presents selected logical and rhetorical fallacies. These fallacies help us to understand common statements, made by
believers, everyday, all around the world.
1.
Ad Hominem - Latin for "to the man," attacking the arguer and not the agrument. An example
might be shooting down somebody's argument based soley on one's dislike for the individual, rather than the content
of their discussion.
2. Argument From Authority - A person's
title, position or even degree (education) cannot be evidence in itself. An example might be arguing that bigfoot exists
because an authority on bigfoot says it is so. Authority itself is not an arguement.
3. Argument From Adverse Consequences - Basically the concept that if we fail to believe a particular concept,
our failure to do so will result in negative consequences, thus, it must be true. An example might be that God must
exist because he rewards and punishes people for their actions. Failure to believe in God would, therefore, result
in chaos and lawlessness. Our culture is not chaotic and lawless, therefore, God must exist.
4. Appeal to Ignorance - A ridiculous fallacy which claims that whatever has not been proven false must be
true, and vice versa. An example might be that since there is no evidence that UFOs aren't true, they must exist.
Another example would be that since there is no evidence that God does not exist, there must be a God.
5. Special Pleading, often to rescue a propostion in deep rhetorical trouble - An example might be somebody
who asks a "believer" how a God could exist that would allow the Holocaust to happen (or a child to be killed in
an accident). The Special Pleading would be, "God works in mysterious ways that we do not understand."
6. Begging The Question (or
Assuming The Answer) - This fallacy occurs when a casual relationship is assumed between two things when no evidence
supports such a relationship. An example might be those who say that we should have a death penalty because it would
discourage violent crime. The fallacy is supported because no such relationship really exists.
7. Observational Selection (aka The Enumeration of Favorable Circumstances) - An example might be a drug
company claiming how favorable their new drug is at fighting disease, yet fails to mention the horrible side-effects that
have been reported in a study. This fallacy is also known as "Counting the hits, and forgetting the misses."
8. Statistics of Small Numbers - This fallacy, closely related to #7 above, relies upon those who either
fail to understand the comparison of small statistics versus large number statistics, or ignore real statistics.
An example might be the craps player who throws three sevens in a row and tells himself that he cannot lose. His arguement
is a fallacy because his odds of continuing to throw sevens has not changed.
9. Misunderstanding
of the nature of Statistics - Any issue in which an argument is made which confuses statistics. For example,
a person who claims there is a difference between half of something and 50% of something. This confusion may also be
prevalent in other mathematical errors (like averages or in reviewing study results).
10. Inconsistency - This fallacy is basically proposing two inconsistent arguements. An example might
be for somebody to consider it reasonable for the Universe to continue to exist forever into the future, but judge absurd
the possibility that it has infinite duration into the past.
11. Non Sequitur - Latin for "It doesn't follow." This fallacy is simply
connecting a cause and efect relationship which make no common sense, and has no supportable evidence. Commonly used
in conjunction with other fallacies. An example would be that a person believes they won a baseball game because God
is looking out for them (wasn't he also looking out for the other team's players as well?). Often, those falling
into the non sequitur fallacy have simply failed to recognize alternative possibilities (like the winning team practiced 10x
more than the losing team).
12. Post Hoc, ergo propter hoc - Latin for "It
happened after, so it was caused by." Carl Sagan's example is perfect: Before women got the vote, there
were no nuclear weapons.
13. Meaningless Question - Posing a question
that cannot be answered due to content of the question itself. For example, "What happens when an irresistable
force meets an immovalbe object?"
14. Excluded Middle, or False Dichotomy - Considering
only the two extremes in a continuum of intermediate possibilities. An example statement might be, "You either
love your country or hate it."
15. Short-Term vs. Long-Term - A derrivation
of #14 in which a black and white approach is taken towards short-term and long-term goals. "Why explore space
or pursue fundamental science when we have so huge a budget deficit?"
16. Slippery Slope
- Basically, the misconception that one thing MUST lead to another related thing. Examples are commonly used in political
arguements. For example, if we allow abortion in the first weeks of pregnancy, we'll soon be aborting a full-term
fetus.
17. Confusion of
Correlation and Causation - Just what it says. An example would be the statement, "A survey shows that
more college graduates are homosexual than those with lesser education; therefore education makes people gay."
18. Straw Man - based on misrepresentation of an opponent's position. To "set up a straw man"
or "set up a straw-man argument" is to create a position that is easy to refute, then attribute that position to
the opponent. A straw-man argument can be a successful technique (that is, it may succeed in persuading people) but it is
in fact misleading, because the opponent's actual argument has not been refuted. An example might be:
- Person A: I don't think children should run into the busy streets.
- Person B: I think that it would be foolish to lock up children all day with no
fresh air.
By insinuating that Person A's argument
is far more draconian than it is, Person B has side-stepped the issue. Here the "straw man" that person B has
set up is the premise that "The only way to stop children running into the busy streets is to keep them inside all day".
19. Suppressed Evidence or Half-Truths - Used when specific information that might undermine a particular arguement is
suppressed purposely to support the arguement. An example might be that a paricular card trick in which a specific card
is found in the deck without the knowledge that it is a trick deck, consisting of 52 copies of only that card.
20. Weasel Words - Utilizing
the spoken or written words themselves to make a proposition more convincing. For example, US Presidents are not allowed
to wage ware without approval from congress; however, they are allowed to call up - police-actions, "armed incursions,"
"protective reaction strickes," "pacification," "safeguarding American interests," and a wide
variety of "operations," like "Operation Iraqi Freedom."
Want to know more about Logical Fallacies? Click Here
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