Logical Fallacies

Overview
Logos is an argument based on reason. It is the ability to construct logical arguments and to persuade others that your assumption is true; therefore, your solution is true. Students will look at misleading notions that are sometimes used.

Objective
Students will be able to give examples of types
of logical fallacies and write statements that contain them.

Standards Addressed
Language Arts — Writing

Communications: Oral and Visual, Listening and Viewing — Benchmark B

Grade 8

02. Identify and analyze the persuasive techniques (e.g., bandwagon,
testimonial, glittering generalities, emotional word repetition and bait and switch) used in presentations and media messages.

Grade 9

02. Identify types of arguments used by the speaker, such as authority and appeals to emotion.

03. Analyze the credibility of the speaker (e.g., hidden agendas, slanted or biased material) and recognize fallacies of reasoning used in presentations and media messages.

Grade 10

02. Interpret types of arguments used by the speaker such as authority and appeals to audience.

03. Evaluate the credibility of the speaker (e.g., hidden agendas, slanted or biased material) and recognize fallacies of reasoning used in presentations and media messages.

 

Communications: Oral and Visual, Listening and Viewing — Benchmark C

Grades 8 and 9

04. Identify the speaker’s choice of language and delivery styles (e.g., repetition, appeal to emotion, eye contact) and explain how they contribute to meaning.

Grade 10

04. Identify how language choice and delivery styles (e.g., repetition, appeal to emotion, eye contact) contribute to meaning.

 

Communications: Oral and Visual, Speaking Skills and Strategies — Benchmark F

Grades 8 and 9

10. Deliver persuasive presentations that:

• Establish and develop a logical and controlled argument.

• Include relevant evidence, differentiating between evidence an opinion, to support a position and to address counter-arguments or listener bias.

• Use persuasive strategies, such as rhetorical devices, anecdotes and appeals to emotion, authority and reason.

 

Communications: Oral and Visual, Speaking Applications — Benchmark F

Grade 9

10. Deliver persuasive presentations that:

• Establish and develop a logical and controlled argument.

• Include relevant evidence, differentiating between evidence and opinion, to support a position and to address counter-arguments or listener bias.

• Use persuasive strategies, such as rhetorical devices, anecdotes and appeals to emotion, authority and reason.

• Consistently use common organizational structures as appropriate (e.g., cause-effect, compare-contrast, problem-solution); and

• Use speaking techniques (e.g., reasoning, emotional appeal, cast studies or analogies).

 

Language Arts — Reading

Reading Applications: Informational, Technical and Persuasive Text — Benchmark B

Grade 8

05. Assess the adequacy, accuracy and appropriateness of an author’s details identifying persuasive techniques (e.g., bandwagon, testimonial and emotional word repetition) and examples of bias and stereotyping.

Grades 9 and 10

04. Assess the adequacy, accuracy and appropriateness of an author’s details identifying persuasive techniques (e.g., transfer, glittering generalities, bait and switch) and examples of propaganda, bias and stereotyping.

Procedure

1. Distribute the Types of Logical Fallacy student handout.

2. Read the following example of a logical fallacy:

There are many examples of logos in the world today. One such example was seen in the 1960s commercial for Excedrin. “I am not a doctor, but I play one on TV.” This is an instance of false authority, when someone who is not an expert but rather a popular celebrity gives testimony. This offers the hope that people will purchase this brand just because a celebrity who is well-liked or is well-known endorses it.

3. Review the types of fallacies and have students give examples of each type from their experience.

4. Either record some commercials from TV, use commercials from the Internet (some sites are listed at www.WesternReservePublicMedia.org/changemymind) or have the students tape commercials from television that illustrate these logic fallacies. Show the commercials and have the students discuss the technique(s) used and name the logical fallacy used.

5. Have the students work with a partner to complete the Logical Fallacies handout.

Answers to Matching Section of Handout

1. B, False Authority

2. I, Prejudicial Language

3. D, Ad Hominem Fallacy

4. E, Complex Question

5. I, Prejudicial Language

6. F, Wrong Direction

7. H, Equivocation

8. C, Hasty Generalization

Evaluation

Using the Logical Fallacies handout, students can earn 1 point for each of the multiple choice questions and 2 points for each one that they write. This is a total of 18 possible points. A percent for the total correct can be used as the evaluation.

Number Correct	Percent
18	100
17	94
16	89
15	83
14	78
13	72
12	67
11	61
10	56
9	50
8	44
7	39
6	33
5	28
4	22
3	17
2	11
1	6