Notes from March 22 and 24th! 

Methods of Persuasion
Logos: Research and Reasoning and Pulling it all Together

Persuasion: How do I turn my evidence into powerful arguments? How do I avoid fallacies?

(Begin with review)

Three Types of Support Material

Are linked to the three modes of persuasion identified by Aristotle.


Evidence and Reasoning

  Identify the flaw (or flaws) in the use of supporting materials in each of the following statements:

         In a random survey last month of 470 members of the Sierra Club, 98 percent of those interviewed opposed drilling for oil in the Alaskan wilderness. Clearly, then, the American people oppose such drilling.

          In the words of one expert, “Mainstream medical care is not meeting the needs of many Americans. I encourage people to pursue alternative treatments such as acupuncture, chiropractic, and massage therapy.”

       Statistics compiled by the National Education Association show that the median salary for teachers in our state is $48,835. This shows that teachers average almost $49,000 a year in salary.

         According to a survey conducted for Verizon Wireless, most people prefer Verizon’s cellular service to that of Cingular, Nextel, or Sprint PCS.

         There’s no reason insurance companies should charge higher rates for drivers under the age of 25. All my friends drive a lot and almost none of them have been in car accidents.

         According to The New York Times Almanac, San Francisco has the highest per capita annual income of any U.S. city—$57,414. The lowest per capita annual income belongs to McAllen-Edinburg-Mission, Texas, at $13,344. The average per capita annual income for all U.S. metropolitan areas is $31,333.

         As Sean Penn noted in a recent interview, the United States needs to change its foreign policy in the Middle East. Otherwise, Penn said, it will be impossible to bring about lasting peace in the region.

Sample Speech: We watched the self defense speech that is at the end of chapter 16.

Reasoning Process: Deduction and Induction.

Deduction refers to arguments that run from general to specific; they are characterized by necessity.
Induction refers to arguments that run from specific to general; they are characterized by an inductive leap.

Classic form of Deduction: the syllogism

The U.S. Constitution guarantees citizens the right to vote.
Women are citizens                                                       .
The U.S. Constitution guarantees women the right to vote.
2. More Typical form of Deduction is called the Enthymeme.  It works like a syllogism but one of the premises is "assumed" rather than stated.  Its strength comes, so some critics argue, from the belief that if the audience supplies the missing premise, then they participate in their own persuasion.

Consider: what do you have to believe for these arguments to make sense?

Our text calls these arguments from principle.
Self-Defense speech example
All people who are vulnerable to personal attacks are people who should take a self-defense course.
[this is the assumed premise]
College students are especially vulnerable to personal attacks.
[this is the premise for which much evidence is presented]
Therefore, college students should take a self-defense course.
[Here is where we picked up lecture on Wed. March 24th]

Boating and Drinking Plan
My plan is to require boater safety education.  My claim is that: Mandatory boater education will result in safer behaviors on the waterways.
What must I believe for that argument to work?  That having information about a safety issue will result in safer behaviors.

Beware the false principle. The major form of Inductive reasoning our text calls argument from specific instances.
Otherwise known as generalization arguments. Generalization in the self-defense speech A Generalization in the Boating and Drinking speech Beware the Hasty Generalization

Arguments from Analogy: Literal or Figurative

Both are grounded in the concept of similarity

Examples of Literal Analogies

Examples of Weak Analogies Figurative Analogies can be useful for framing an argument, but they don't constitute proof. Causal Arguments
The most challenging of the types of reasoning.
We cant see causal relationships, we can only infer them.

Problems of Causal Arguments

Tips for success in causal reasoning. The textbook also discusses several additional types of fallacies including: slippery slope, red herring, Either-Or fallacy, ad hominem, and bandwagon.  Read that discussion for more information.

Can you identify the kind or reasoning and or the fallacy in the following examples?
Once you have tried to answer these on your own you can go here for answers and discussion.

1. According to a study by the American Medical Association, men with bald spots have three times the risk of heart attack as men with a full head of hair.  Strange as it may seem, it looks as if baldness is a cause of heart attacks.

2. The U.S. Constitution guarantees all citizens the right to bear arms.  Gun control legislation infringes on the right of citizens to bear arms.  Therefore, gun control legislation is contrary to the Constitution.

3.  I don’t see any reason to wear a helmet when I ride a bike. Everyone bikes without a helmet.

  4. It’s ridiculous to worry about protecting America’s national parks against pollution and overuse when innocent people are being killed by domestic terrorists.

 5. There can be no doubt that the Great Depression was caused by Herbert Hoover.  He became President in March 1929, and the stock market crashed just seven months later.

6. If we allow the school board to spend money remodeling the gymnasium, next they will want to build a new school and give all the teachers a huge raise.  Taxes will soar so high that businesses will leave and then there will be no jobs for anyone in this town.

7. Raising a child is like having a pet--you need to feed it, play with it, and everything
will be fine.

8. One nonsmoker, interviewed at a restaurant, said, “I can eat dinner just fine even though people around me are smoking.”  Another, responding to a Los Angeles Times survey, said, “I don’t see what all the fuss is about.  My wife has smoked for  years and it has never bothered me.”  We can see, then, that secondhand smoke does not cause a problem for most nonsmokers.

9. I can’t support Representative Frey’s proposal for campaign finance reform.  After all, he was kicked out of law school for cheating on an exam.

10. Our school must either increase tuition or cut back on library services for students.

As you prepare your speeches don't forget to go beyond LOGOS issues to make sure you are using Ethos and Pathos as well.

ETHOS: Building credibility throughout your speech

Pathos: Building Emotional Appeals Throughout your Speech
It is a great idea to watch the sample speeches on your textbook CD-ROM and to read the sample speeches in the text and workbook to look for the ways others have used Logos, Ethos and Pathos and also to review the central concepts of Problem, Plan, Practicality in their speeches.

WORKSHOP:  On Friday only those students who speak next week should come with their completed outlines for workshop day.