Unit Four : Part Three

Logical Fallacies

Fallacies are arguments that seem valid but are flawed because of unsound evidence or reasoning

There are lots (125+)! You only need to know 7.

Types of Reasoning

Red Herring

Ad Hominem

Bandwagon

Hasty Generalization

Either-Or

(False Dilemma)

False Cause

Introduction of irrelevant information into an argument to distract from the real issue/topic

Ex. How can we worry about limited poverty in American when there are millions elsewhere

Argument that suggests something has merit because everyone else agrees with it or is doing it

Ex. Other schools are not adapting a zero-tolerance policy, why should we?

Argument in which a speaker attacks a person rather than his or her arguments (debates)

Ex. Of course Obama worked so hard to pass the health-care bill, he's a liberal democrat who only wants to create a socialist country

Argument based on too few cases or examples to support a conclusion

Ex. It is impossible to get accepted to the business school. I applied three times and was not accepted.

Use lots of evidence

Argument that mistakes a chronological relationship for a causal relationship

Ex. After the death penalty was passed, violent crimes decreased. The death penalty deterred criminal activity

Argument that presents only two options (either A or B) when actually more than two options exist

Ex. "You are either for us or you are against us"

Either we increase our candidate's appeal to women or we don't get elected

Reasoning by Sign

Tips for Reasoning

yourlogicalfallacyis.com

Slippery Slope

Argument that claims a first step in a certain direction will inevitably lead to undesirable further steps in that direction

Ex. If children dress themselves, they will compete for the most outrageous outfits and will eventually become violent

"snowball effect"

Build your credibility

• competence
• character

Use accurate evidence

Verify the structure of your reasoning

Definition: process of reasoning that assumes something exists or will happen based on something else that exists or has happened (266)

Examples:

Dark clouds are a sign that a storm is coming

Decrease in college applications is a sign of lower interest in higher education

Activity:

In groups of 3-4, generate a short list of examples that follow the definition of one type of reasoning. Record them and be willing to discuss as a class in 5 min.

• Inductive
• Deductive
• Analogical
• Causal
• Sign

In summary:

Types of Reasoning

• Be intentional with logos and reasoning in your speech
• Avoid logical fallacies
• Always be audience-centered

Causal Reasoning

Analogical Reasoning

Questions?

Definition: process of reasoning that supports a claim by establishing a cause-and-effect or "if-then" relationship (263)

Examples:

• If I don't study, then I'll do poorly on my exam
• If I wear my lucky socks, then I'll ace my exam

Be careful of false cause

Definition: a process of reasoning by way of comparison and similarity that implies that because two things resemble each other in one respect, they also share similarities in another respect (264)

Example: Health concerns for the food industry like the tobacco industry

Chapter 14: Reasoning

According to Aristotle, there are three main types of proofs:

• Logos (logical arrangement of evidence)
• Ethos (speaker's credibility)
• Pathos (emotional appeals)

Types of Reasoning

Effective persuasive speaking strategically uses reasoning (logos) in order to persuade audience members

Reasoning enables inferences through evidence given in arguments

Inductive Reasoning

Definitions (pg. 259)

Inferences are mental leaps we make when we recognize that a speaker's evidence supports his or her claims

Evidence is material you use to support your ideas, and it consists of examples, narratives, statistics, testimony, and definitions

Argument is a set of statements that allows you to develop your evidence to establish the validity of your claim (logical arrangement of evidence)

The goal is to reduce mental leaps through strong evidence, clarity of argument, and thoughtful reasoning

Definition: process of reasoning that uses specific instances, or examples, to make a claim about a general conclusion (260)

Example:

my older sister is a pianist (specific instance)

I am a guitarist (specific instance)

my younger brother is a drummer (spec. instance)

Conclusion: my youngest sibling will be a musician

"It's elementary, Watson" (inferences)

Hasty Generalization (261) "error in reasoning"

Sherlock Holmes

Types of Reasoning

Deductive Reasoning

Definition: process of reasoning that uses a familiar and commonly accepted claim to establish the truth of a very specific claim

Example:

Cats have a keen sense of smell (major premise)

Fluffy is a cat (specific instance/minor premise)

Fluffy has a keen sense of smell (conclusion)

Make sure your major and minor premises are valid. Otherwise, you can be logical but false

Monty Python

Agenda Items

Looking Ahead:

• Policy Speech Round (starts Thurs.)
• Vericite Submissions (before class)
• Be ready to ask questions (participation requirement)

Today:

• Chapter 14
• Preparing for the Policy Speech

Unit Four : Part Three

Chapter 14