This document discusses various types of informal fallacies that can undermine logical arguments. It begins by defining fallacies as flawed arguments that may seem initially correct but are actually invalid. It then examines fallacies of ambiguity, relevance, unwarranted assumptions, and provides strategies to avoid committing fallacies. The overall aim is to help readers recognize and avoid fallacious reasoning.

1. INFORMAL FALLACIES
The aim of this tutorial is to help you learn to
recognize and resist fallacious arguments.

2. Fallacies are dangerous
Fallacies, or flawed arguments, are often used by cult
recruiters on college campuses to target freshmen.
Critical thinking is the antidote to fallacious arguments. By
recognizing fallacies and other types of flawed arguments,
we can protect ourselves against those seeking to control
or manipulate us.
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3. Fallacies: formal and informal
An argument is the process of supporting a claim by
providing reasons or evidence for that claim. An argument
contains a fallacy when it appears to be initially correct,
but upon further examination is found to be incorrect.
In formal fallacies, the form of the argument itself is
invalid.
An informal fallacy is mistaken reasoning that occurs
when an argument is psychologically or emotionally
persuasive but logically incorrect.
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4. Hot or Not?
Is the use of fallacies a legitimate
political campaign tactic?
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5. Fallacies of ambiguity
 Arguments that contain ambiguous words or
phrases, sloppy grammar, or confusion between two
closely-related concepts can lead to fallacies of
ambiguity.
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6. Fallacies of ambiguity (continued)
 Four types of fallacies of ambiguity:
 Equivocation occurs when a key term in an argument is
ambiguous—when it has more than one meaning.
 Amphiboly occurs when an argument contains a grammatical
mistake.
 Fallacies of accent occur when an argument’s meaning changes
depending on which words or phrases are emphasized.
 Fallacies of division occur when we make erroneous inferences
from group characteristics about those of individuals within the
group.
 Fallacies of composition occur when a characteristic of a
member of a group is erroneously assumed to be characteristic
of the whole group.
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7. Tiger Woods is a good golfer, therefore
Tiger Woods is a good husband.
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8. Men are taller than women.
Danny DeVito is a man.
Therefore, Danny DeVito is taller than the average woman.
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9. Fallacies of relevance
In fallacies of relevance, one or more of the premises is
logically irrelevant, or unrelated, to the conclusion.
Fallacies of relevance include personal attacks or
ad hominem fallacies; appeals to force or scare tactics;
appeals to pity; popular appeals; appeals to ignorance;
hasty generalizations; straw man fallacies; and red
herrings.
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10. Ad hominem and appeal to force
 The ad hominem fallacy occurs when we disagree with
another’s conclusion and attack them personally instead
of presenting a valid counter-argument.
 The appeal to force fallacy occurs when we use or
threaten to use force in an attempt to get others to back
down or accept our conclusions.
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11. The ad hominem fallacy may occur between
people in personal relationships.
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12. Darwin’s descent from the apes
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13. Appeal to pity and popular appeal
 The appeal to pity fallacy occurs when we try to evoke
feelings of pity in others when pity is irrelevant to the
conclusion.
 The fallacy of popular appeal occurs when we appeal
to popular opinion to gain support for our conclusion.
Two types of this fallacy include the bandwagon
approach and the snob approach.
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14. The appeal to pity on this billboard is not fallacious.
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15. “I shouldn’t get a ticket
because everyone speeds.”
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16. Appeal to ignorance and hasty
generalization
 The appeal to ignorance fallacy occurs when we try to
argue something is true because no one has proven
it false.
 The fallacy of popular appeal occurs when we
generalize from a sample that is too small or biased.
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17. Hot or Not?
Does celebrity endorsement of a
product make you more likely to
buy that product?
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18. “You’ve come a long way, baby.”
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19. “I want to be like Victoria Beckham, so I’ll
buy the type of purse she is carrying.”
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20. Straw man and red herring fallacies
 The straw man fallacy occurs when a person distorts or
misrepresents the opponent’s argument, making it
easier to knock down or refute.
 The red herring fallacy occurs when a person tries to
sidetrack an argument by going off on a tangent and
bringing up a different issue directed toward a different
conclusion.
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21. Rhetoric
 When we start with a position statement, rather than
with an open-ended question that invites exploration and
analysis of an issue, we are using rhetoric.
 Rhetoric, also known as the art of persuasion, is used
to promote a particular position or worldview.
 Although it has its uses, rhetoric becomes a problem
when it is substituted for unbiased research and logical
argumentation. When using rhetoric this way, people
only present claims that support their own position.
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22. Argumentation
 Whereas the purpose of rhetoric is to persuade people
of what you consider to be the truth, the purpose of
argumentation is to discover the truth.
 Unlike rhetoric, arguments are open to multiple
perspectives.
 Good arguments provide evidence and reasons and
invite feedback analysis.
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23. Fallacies involving unwarranted
assumptions
Fallacies involving unwarranted assumptions occur
when an argument includes an assumption that is not
supported by evidence.
Fallacies involving unwarranted assumptions include
begging the question, inappropriate appeal to authority,
loaded question, false dilemma, questionable cause,
slippery slope, and the naturalistic fallacy.
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24. Begging the question and
inappropriate appeal to authority
 The begging the question fallacy occurs when an
argument’s conclusion is simply the rewording of its
premise. This fallacy is also known as circular
reasoning.
 The inappropriate appeal to authority fallacy occurs
when we look to an authority in a field that is unrelated
or not under investigation.
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25. A uniform gives the idea that the person is an authority
in fields that may be beyond his or her expertise.
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26. Loaded question and false dilemma
 The loaded question fallacy occurs when a question is
asked that assumes a particular answer to another
unasked question.
 The false dilemma fallacy reduces responses to
complex issues to an either/or choice. By doing so, this
fallacy polarizes stands on issues and ignores common
ground or other solutions.
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27. It’s not a choice of only oil or
alternative energies.
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28. Questionable cause and slippery slope
 The questionable cause or post hoc fallacy occurs
when a person assumes, without sufficient evidence,
that one thing is the cause of another.
 According to the slippery slope fallacy, if we permit a
certain action, then all actions of this type, even extreme
ones, will soon be permissible.
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29. Babe Ruth jinxed the Red Sox in 1920.
Their World Series win in 2004 was attributed to
“the end of the curse.”
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30. The naturalistic fallacy
 The naturalistic fallacy is based on the unwarranted
assumption that what is natural is good or morally
acceptable and that what is unnatural is bad or morally
unacceptable.
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31. Same-sex parents are often discriminated against
because many people only see “parents” as a
mother and father.
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32. Strategies for avoiding fallacies
 Once you have learned to identify informal fallacies, the
next step is to develop strategies to avoid them.
 The following strategies are recommended:
 Know yourself and the fallacies you are most
susceptible to.
 Build your self-confidence and self-esteem.
 Cultivate good listening skills; study others’ arguments
for fallacies.
 Avoid ambiguous, vague terms and faulty grammar.
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33. More fallacy avoidance strategies
 Avoid confusing the soundness of an argument with the
character or circumstances of the person making the
argument.
 Know your topic. Do your research.
 Adopt a skeptical “default” position.
 Watch your body language. Avoid inflammatory actions.
 Don’t be set on winning every argument. Seek the truth,
not victory.
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34. Conclusions
Use of fallacies in communication can damage
relationships and impair sound critical thinking.
Identification and avoidance of fallacies through the use
of effective strategies can improve our relationships with
others and increase the credibility of our arguments.
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35. Perspectives on going to war in Iraq
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