"You don't need to take drugs to hallucinate;
improper language can fill your world with phantoms and spooks of many
-Robert A. Wilson
When arguing with someone in an attempt to get
at an answer or an explanation to a theory, you may come across a
person who makes logical fallacies. Such discussions may prove futile.
You might try asking for evidence and independent confirmation or
provide other hypothesis that give a better or simpler explanation. If
this fails, try to pinpoint the problem of your arguer's position. You
might spot the problem of logic that prevents further exploration and
attempt to inform your arguer about his fallacy. The following briefly
describes some of the most common fallacies:
1. Ad hominem: Latin for "to the man." An
arguer who uses ad hominem attacks the person instead of the argument.
Whenever an arguer cannot defend his position with evidence, facts or
reason, he or she may resort to attacking an opponent either through:
labeling, straw man arguments, name calling, offensive remarks and
2. Appeal to ignorance (argumentum ex
silentio) appealing to ignorance as evidence for something. (e.g., We
have no evidence that God doesn't exist, therefore, he must exist. Or:
Because we have no knowledge of alien visitors, that means they do not
exist). Ignorance about something says nothing about its existence or
3. Argument from omniscience: (e.g.,
All people believe in something. Everyone knows that.) An arguer would
need to be omniscient to know about everyone's beliefs or disbeliefs or
about their knowledge. Beware of words like "all," "everyone,"
4. Appeal to faith: (e.g., if you have
no faith, you cannot learn) if the arguer relies on faith as the bases
of his argument, then nothing more can be gained from further
discussion. Faith, by definition, relies on a belief that does not rest
on logic or evidence. Faith depends on irrational thought and produces
5. Appeal to tradition (similar to the
bandwagon fallacy): (e.g., astrology, religion, slavery) just because
people practice a tradition, says nothing about its viability
6. Argument from authority (argumentum ad
verecundiam): using the words of an "expert" or authority as the bases
of the argument instead of using the logic or evidence that supports an
argument. (e.g., Professor so-and-so says creation-science is correct.)
Simply because an authority makes a claim does not necessarily mean he
got it right. If an arguer presents the testimony from an expert, look
to see if it accompanies reason and sources of evidence behind it.
7. Argument from adverse consequences:
(e.g., The accused must be found guilty, otherwise others will commit
similar crimes) Just because a repugnant crime or act occurred, does
not necessarily mean that a defendant committed the crime or should be
sentenced. (Or: disasters occur because God punishes non-believers;
therefore, we should all believe in God) Just because calamities or
tragedies occur, says nothing about the existence of gods or that we
should believe in a certain way.
8. Argumentum ad baculum: An argument
based on an appeal to fear or a threat. (e.g., If you don't believe in
God, you'll burn in hell)
9. Argumentum ad ignorantiam: A
misleading argument used in reliance on people's ignorance .
10. Argumentum ad populum: An argument
aimed to sway popular support by appealing to sentimental weakness
rather than facts and reasons.
11. Bandwagon fallacy: concluding that
an idea has merit simply because many people believe it or practice it.
(e.g., Most people believe in a god; therefore, it must be true.)
Simply because many people may believe something says nothing about the
fact of that something. For example many people during the Black plague
believed it was caused by demons. The number of believers say nothing
about the cause of disease.
12. Begging the question (or assuming
the answer): (e.g., We must encourage our youth to worship God to
instill moral behavior.) But does religion and worship actually produce
13. Circular reasoning: stating in one's
proof that which one is supposed to be proving. (e.g. God exists
because the Bible says so; the Bible exists because God influenced it.)
14. Composition fallacy: when the
conclusion of an argument depends on an erroneous characteristic from
parts of something to the whole or vice versa. (e.g., Humans are
conscious and are made of atoms; therefore, atoms have consciousness.
Or: a word processor program consists of many bytes; therefore a byte
is a fraction of a word processor.)
15. Confusion of correlation and causation:
(e.g., More chess players are men, therefore, men make better chess
players than women. Or: Children who watch violence on TV tend to
become violent when they grow up.) But does television programming
cause violence or do violence oriented children prefer to watch violent
programs? Perhaps an entirely different reason creates violence not
related to television at all. Stephen Jay Gould called the invalid
assumption that correlation implies cause as "probably among the two or
three most serious and common errors of human reasoning" (The
Mismeasure of Man).
16. False dichotomy: considering only the
extremes excluding middle. Many people use Aristotelian either/or logic
tending to describe in terms of up/down, black/white, true/false,
love/hate, etc. (e.g., You either like it or you don't. He's either
guilty or not guilty.) Many times, a continuum occurs between the
extremes that people fail to see. The universe also contains many
17. Half truths (suppressed evidence): A
statement usually intended to deceive that omits some of the facts
necessary for an accurate description.
18. Loaded questions: embodies an
assumption that, if answered, indicates an implied agreement. (e.g.,
Have you stopped beating your wife yet?)
19. Meaningless question: (e.g., How high
is up? Is everything possible?) "Up" describes a direction, not a
measurable entity. If everything were possible, then it would be
possible for the impossible, a contradiction. Although everything may
not be possible, there may be an infinite number of possibilities as
well as an infinite number of impossibilities.
20. Misunderstanding the nature of statistics:
(e.g., the majority of people in the United States die in hospitals,
therefore, stay out of them.) "Statistics show that of those who
contract the habit of eating, very few survive." -- Wallace Irwin
21. Non sequitur: Latin for "It doesn't
follow." An inference or conclusion that does not follow from
established premises or evidence. (e.g., there was an increase of
births during the full moon. Conclusion: full moons cause birth rates
to rise.) But does a full moon actually cause more births, or did it
occur for other reasons, perhaps from expected statistical variations?
False premis, false conclusion.
22. Observational selection: pointing out
favourable circumstances while ignoring the unfavorable. Anyone who
goes to Las Vegas gambling casinos will see people winning at the
tables and slots. The casino managers make sure there's bells and
whistles to announce the victors, while the losers are never mentioned.
This may lead one to conclude that the chances of winning are good
while in actually just the reverse is true.
23. Post hoc, ergo propter hoc: Latin
for "It happened after, so it was caused by." Similar to a non
sequitur, but time dependent. (e.g. She got sick after she visited
China, so something in China caused her sickness.) Perhaps her sickness
derived from something entirely independent from China.
24. Proving non-existence: when an arguer
cannot provide the evidence for his claims, he may challenge his
opponent to prove it doesn't exist (e.g., prove God doesn't exist;
prove UFO's aren't real, etc.). Although one may prove non-existence in
special limitations, such as showing that a box does not contain items,
one cannot prove universal or absolute non-existence, or non-existence
out of ignorance. One cannot prove something that does not exist. The
proof of existence must come from those who make the claims.
25. Red herring: when the arguer diverts
the attention by changing the subject.
(Insert) reductio ad absurdum
26. Reification fallacy: when people
treat an abstract belief or hypothetical construct as if it represented
a concrete event or physical entity. Examples: IQ tests as an actual
measure of intelligence; the concept of race (even though genetic
attributes exist), from the chosen combination of attributes or the
labelling of a group of people, come from abstract social constructs;
Astrology; god(s); Jesus; Santa Claus.
27. Slippery slope: a change in
procedure, law, or action, will result in adverse consequences. (e.g.,
If we allow doctor assisted suicide, then eventually the government
will control how we die.) It does not necessarily follow that just
because we make changes that a slippery slope will occur.
28. Special pleading: the assertion of
new or special matter to offset the opposing party's allegations. A
presentation of an argument that emphasises only a favourable or single
Aspect of the question at issue. (e.g. How can God
create so much suffering in the world? Answer: You have to understand
that God moves in mysterious ways and we are not privileged to this
knowledge. Or: Horoscopes work, but you have to understand the theory
29. Statistics of small numbers: similar
to observational selection (e.g., My parents smoked all their lives and
they never got cancer. Or: I don't care what others say about Yugos, my
Yugo has never had a problem.) Simply because someone can point to a
few favorable numbers says nothing about the overall chances.
30. Straw man: creating a false scenario
and then attacking it. (e.g., Evolutionists think that everything came
about by random chance.) Most evolutionists think in terms of natural
selection which may involve incidental elements, but does not depend
entirely on random chance. Painting your opponent with false colors
only deflects the purpose of the argument.
31. Two wrongs make a right:
trying to justify what we did by accusing someone else of doing the
same. (e.g. who are you to judge my actions when you do exactly the
same thing?) The guilt of the accuser is irrelevant to the discussion.
Science attempts to apply some of the
1) Scepticism of unsupported claims 2)
Combination of an open mind with critical thinking 3) Attempts to
repeat experimental results. 4) Requires testability 5) Seeks out
falsifying data 6) Uses descriptive language 7) Performs controlled
experiments 8) Self-correcting 9) Relies on evidence and reason 10)
Produces useful knowledge
Pseudo-science and religion relies on some of
the following criteria
1) Has a negative attitude to scepticism 2) Does
not require critical thinking 3) Does not require experimental
repeatability 4) Does not require tests 5) Does not accept falsifying
data 6) Uses vague language 7) Relies on anecdotal evidence 8) No
self-correction 9) Relies on belief and faith 10) Produces no useful
Some of this information derived in part from:
William D. Gray, "Carl Sagan, "," Random House, New York, 1995 Houghton