Introduction to Logos

Logos as Reasoning

Fact and Opinion

• What is a “fact” and how can you tell?• What are some “facts” you know? Where

do you find them?• What is an opinion? How can you tell that

from a fact?• Is it possible to have contradictory facts?• How are facts found out/discovered/known?• How do you form an opinion about

something?

Logos: Definition

• Logos is the art of using facts and reasoning for effective argumentation– Reasoning: Inductive and Deductive– Logical Fallacies / Where reasoning

breaks down– Reasoning: Syllogisms

Deduction

• Deduction: Process of starting with universals / assumptions and leading to specifics

• General -> specific• Example: 1) All people are mortal; 2) Chuck

Norris is a person; 3) Therefore Chuck Norris is mortal

Induction

• Induction: Process of leading from particulars to universals / general conclusions

• Specific examples -> General conclusion• Example:• If Chuck Norris is good at kicking, and Chuck

Norris is good at punching, Chuck Norris must be good at all martial arts.

Syllogisms and Enthymemes?

• Logos isn’t just about using facts or statistics in argument, but rather its about being able to use those facts through reasoning.

• Syllogisms & enthymemes are two ways to reason in an argument.

What is a syllogism?

• A type of deductive reasoning (general to specific)

• Consists of a major premise, a minor premise, and a conclusion

• Almost any argument can be broken down into a syllogism.

Premises

• Major premise: A general statement.• Minor premise: A specific statement.• Conclusion: based on the two

premises.

Example I

• Healthcare is too costly in America• Most middle-class families and employers

cannot afford heathcare costs. • Therefore, we need healthcare reform in

America

Example II

• All people regardless of race were created equal and have rights.

• Segregation in schools and busses treats people unequally.

• Therefore, we need a constitutional amendment to guarantee equality for all.

Example III

• "The gloves didn't fit. If it doesn't fit, you must acquit."-- Johnny Cochran, Closing arguments of the O.J. Simpson trial

• The glove was used in the murder and therefore owned and worn by the murderer. (major premise)

• The gloves didn't fit. (minor premise)• You must acquit. (conclusion)

Examples V• Tomatoes taste salty.

Tomatoes are red. All red foods taste salty.

• Bobby stole a bicycle. Bobby is poor. All poor people are thieves.

• Snails crawl on the ground.I can crawl on the groundTherefore, I’m a snail.

The point?

• While they can be a powerful tool, syllogisms can also lead to overgeneralizations and faulty reasoning.

• In groups: write two syllogisms based on arguments in current American politics

Enthymemes

• Enthymemes are like syllogisms except that they are missing the minor premise.

• These are used more frequently than syllogisms in written and spoken arguments.

Examples of Enthymemes

• “Women should be allowed to join combat units because the image of women in combat would help eliminate gender stereotypes.”

• Claim: Women should be allowed to join combat units.• Stated Reason: Because the image of women in combat would

help eliminate gender stereotypes.• Unstated Assumption: Gender stereotypes are harmful and should

be eliminated (or girls with guns = cool?)

Examples

Buy this car stereo system because it has a 200-watt amplifier.

Claim: Buy this car stereo system

Reason: Because it has a powerful amplifier

Unstated assumption: loud music rocks / loud car stereo systems are cool

Example• The ladies like “Axe” body spray• (“Axe” smells great.)• If you use “Axe”, you’ll attract women

But what about bad reasoning?

• Logical or verbal fallacies - incorrect, bad, faulty reasoning– Can lead readers astray– Can be incredibly convincing!

Fallacies Activity - Skits

• Using the list of Logical Fallacies, develop a short skit of your assigned fallacy.

• Be prepared to present your skit to the class.

• Groups who guess correctly can earn up to 5 bonus points.

Arguments in Action• In groups, analyze, “Third Party Rising” in the New York

Times (Op Ed): http://www.nytimes.com/2010/10/03/opinion/03friedman.html?_r=1&src=me&ref=general

• Answer the following questions (in groups)– What is the overall argument?

• What is the supporting evidence?

– What appeals are being made from ethos?– What reasoning is being used? Inductive or Deductive?– Identify at least two syllogisms or enthymemes– Are there any fallacies? If so, what are they?