Lecture 8: Arguing from Evidence

1. Using evidence to support your arguments

2. Testing your arguments

Today’s lecture will help students

1. Evaluate the other people’s arguments

2. For the argumentative research paper: Formulate arguments using available evidence

3. In general: Evaluate the strength of their own reasoning

Overview

1. Quasilogical arguments: (a) transitivity, (b) incompatibility, and (c) reciprocity

2. Arguments from comparison

3. Arguments from generalization

4. Argument from examples

5. Argument from cause

6. Argument from sign

A. Quasilogical Arguments

Transitivity– Three terms associated through the process of

classification

A is BB is C

A is C

A. Quasilogical Arguments

Example:

Because coffee is an antioxidant,

it prevents cancer.

What are the premises?

What is the conclusion?

Testing the argument

Are there only three terms? Does the middle term mean the same in the

two premises? Are all premises true?

All men are animals.

My ex-boyfriend is a man; so he’s an animal.

A. Quasilogical Arguments

Incompatibilities– Expresses two choices, usually contradictory,

between which a choice must be made

Example:

President Aquino cannot be pro-education as he claims to be. He reduced the budget of state colleges and universities by half.

Testing the argument

Are the two terms mutually exclusive or contradictory?

"You're either with us or against us in the fight against terror."

After comparing using traditional brick-and-mortar libraries and using the Internet for research, it is clear that using the Internet is the better option for researchers. Thus, students should focus solely on using the Internet for research.

Reciprocity– Individuals and situations that can be put together

in the same category should be treated in the same way

Legalizing prostitution means prostitutes will be entitled to healthcare. The government can also earn by taxing their income.

Testing the argument

Can the term be logically subsumed under the other term?

B. Argument from Comparison

A B

C D

A B

C D?

Entity X Entity Y

Therefore, entity Y will have D as well.

Example:

The RH Law will lead to the legalization of abortion in the Philippines. This was the case in Vietnam which enacted a similar law many years ago.

Testing the argument

Do the two entities belong to the same category?

Are the two entities sufficiently similar to justify the conclusion?

Is there any significant dissimilarity to undermine the conclusion?

C. Argument from Generalization

D. Argument from examples

POPULATION

Manny Pacquiao is proof that the Philippines is a nation of good boxers.

Cartoons expose children to excessive violence. Shows like Tom and Jerry, Bugs Bunny, and The Power Puff Girls show an average of seventeen violent acts (e.g. punching, kicking, hitting with an instrument) per episode.

Testing the argument

Argument from generalization: Is the member representative of the entire population?

Argument from examples: – Is there a sufficient number of examples to justify

the conclusion?– Are there any counter-examples?

E. Argument from cause

Strong cause / sufficient cause

The occurrence of the cause guarantees the existence of the effect.

Weak cause / necessary cause

The occurrence of the cause is necessary for the effect to occur.

Testing the argument

Is the relationship really causal?

Statistics show that crime rate in any US state can be correlated with ice cream consumption: states with higher consumption have higher crime rates. This may suggest that ice cream consumption leads to criminal behavior.

Is the cause a sufficient or necessary cause?

1. High tuition fee = better quality of education

2. Presence of water in a planet = presence of life

3. Smoking = cancer

4. Pre-adolescent smoking of parent = shorter life span for the offspring

Argument from sign

Index or indicator

A sign or indicator X signifies the existence of Y.

What are the following signs of?1. Smoke in a building

2. Body temperature of 40 degrees C or higher

3. A classmate of the opposite sex constantly texting even without any apparent reason (e.g. “how u n? la lang…”, “kmain n u? aq d p”)

Argument from authority

An expert serves as the sign

Testing the argument

Is the relationship between the sign and the signified consistent?

Are there other indicators that show the opposite of what is concluded?