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Rhetorical / Logical Fallacies
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Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Dec 16, 2015

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Morris Pierce
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Page 1: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Rhetorical / Logical Fallacies

Page 2: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

What is a Fallacy?

• An argument must be based on sound reasoning

• Fallacies are flaws in reasoning that detract from the validity or soundness of an argument

• Sometimes their use is by accident; others, they are used to deliberately mislead or “win” an argument

Page 3: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Example: "Eating five candy bars and drinking two sodas before a test helps me get better grades. I did that and got an A on my last test in history.”

What’s wrong with this line of reasoning?

Page 4: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Answer: The argument is fallacious because it falsely assumes that since the one thing (eating five candy bars) immediately precedes the other (getting an A), the relationship is causal.

Page 5: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Categories of Rhetorical Fallacies

Since there are three primary argumentative modes, there are three categories of fallacies:

• Logical (Logos) – Flaws in logical reasoning

• Ethical / Authoritative (Ethos) – Appealing to authority or morality on its own terms

• Emotional (Pathos) – Trying to manipulate emotionally or to scare people

Page 6: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Fallacies of Logic

• Hasty Generalization

• Post Hoc

• Non sequitur

• Equivocation

• Begging the Question

• Faulty Analogy

• Stacked Evidence

Page 7: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Hasty Generalization

• Conclusion is drawn based on little or insufficient evidence

• Example: “That restaurant’s food is terrible! I ate there once and my food was undercooked.”

• Why is this fallacious?

Page 8: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Post Hoc, Ergo Propter Hoc

• Latin for “after this, therefore also this”• Assumes that because an event happens before

another event, that the first event actually causes the second

• Also known as false cause fallacy• Example: “A year after the release of the violent

shoot-’em-up video game Annihilator, incidents of school violence tripled… surely not a coincidence.”

• Why is this fallacious?

Page 9: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Non sequitur

• Latin for “it doesn’t follow”• Argument does not follow any sort of logical

sequence• Example: “It rained so hard that Jenn

actually called me!”• Example: “My dog got so sick that my

grandma made stew.”• What’s wrong with these arguments?

Page 10: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Equivocation

• Commonly referred to as “half-truths”

• A partially correct statement that tries to hide behind double meanings

• Example: “I did not have sexual relations with that woman.” – Former President Bill Clinton

Page 11: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Begging the Question

• Circular argument• The premise and the

conclusion are the same thing stated differently

• Example: “His lies are evident from the untruthful nature of his statements.”

Page 12: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Faulty Analogy

• An inaccurate, inappropriate comparison between two things

• Example: “Forcing students to attend cultural events is like leading cattle to slaughter.”

Page 13: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Stacked Evidence

• Distorts an issue by overwhelmingly supporting or representing only one part of it

• Usually done intentionally to make one particular part of an issue appear clearly favorable to the others

• Example: “Cats are superior to dogs because they are cleaner, cuter, and smarter.”

Page 14: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Ethical / Authoritative Fallacies

• False Authority

• Authority as Evidence

• Guilt by Association

• Dogmatism

• Ad Hominem

• Strawman

Page 15: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

False Authority

• Claims that an assertion is true based solely on the person who made the assertion

• Example: “Mr. King says that the sky is red, and Mr. King is smart, so it must be true.”

Page 16: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Authority as Evidence

• A speaker uses his or her own authority to prove that a claim is true

• Usually such claims are totally unrelated to the speaker’s own expertise

• Example: “Dr. Pepper is smooth. Trust me – I’m a doctor.”

• Example: “My friend would never rob a bank. Trust me.”

Page 17: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Guilt by Association

• Assumes that an argument is true because the person involved is associated with someone or something negative

• Example: “Tom’s friend robbed a bank, so Tom is a bad person.”

Page 18: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Dogmatism

• A claim is assumed true because the speaker believes it to be true

• Otherwise known as “because I said so”• Example: “Penguins are reptiles, and that’s

that.”

Page 19: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Ad Hominem

• Instead of debating an issue, the speaker attacks the person who makes a competing claim

• Often seen in political campaigns• Example: “How can we trust Ms. Ware to run

the city when she can’t even handle her own marriage?”

• Example: “Senator Kelly’s plan is terrible because Kelly is a communist.”

Page 20: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Strawman

• A speaker misrepresents or oversimplifies an opposing view in order to tear it down

• Example: – A: We need to fix welfare.– B: Welfare is for terrorists.

Do you really think we should be aiding terrorists?

Page 21: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Emotional Fallacies

• Red Herring

• Scare Tactics

• Bandwagon

• Slippery Slope

• Either / Or

Page 22: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Red Herring

• Using misleading or unrelated information to prove a conclusion

• Example: "Winthrop should pave the lot behind Dinkins. Besides, I can never find a parking space on campus anyway."

Page 23: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Scare Tactics

• Tries to manipulate people’s fears to sway their decisions

• Example: “If you don’t vote for Q for President, the economy will implode and your family will starve.”

Page 24: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Bandwagon

• Implies that a choice is correct because it is popular

• Often used in advertising – celebrity spokesperson

• Example: “Five million Coke drinkers can’t be wrong!”

Page 25: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Slippery Slope

• Argues that one thing automatically will lead to another – usually with disastrous results

• The cause and effect relationship often is completely exaggerated or absurd

• Example: “If we allow gay marriage, then people will start marrying their pets, and the fabric of society will crumble.”

Page 26: Rhetorical / Logical Fallacies. What is a Fallacy? An argument must be based on sound reasoning Fallacies are flaws in reasoning that detract from the.

Either / Or Choices

• Setting up a false dichotomy for an issue• Inaccurately reduces an issue to two possible

outcomes• Usually one outcome is absurd and the other

is infinitely favorable• Example: “You can either approve the new tax

plan or you can say goodbye to adequate emergency services!”