Judging deceptive or faulty arguments in persuasive texts

SPOTTING FAULTY LOGIC

DO YOU BELIEVE EVERYTHING YOU SEE?

DO YOU BELIEVE EVERYTHING YOU READ? Advertisements are designed to get

you to buy things. Do you buy what you see on every ad?

Newspaper and magazine editorials are written to get readers to share the author’s point of view. Do you agree with everything you read?

Letters to the editor are citizen’s responses to what they’ve read in print media. Do you believe everything every stranger writes?

DO YOU BELIEVE EVERYTHING YOU READ? If you answered to no to each of the previous

questions (and I hope you did!), why did you answer that way?

If you think about people’s reasons for advertising and writing you’re off to a great start. However, if you begin to look at specific ways people to try to persuade you to buy, feel, think, or do certain things, you’ll be able to make more informed decisions.

WHY MIGHT AN AUTHOR OR SPEAKER BE DISHONEST? They may earn money by getting you to buy

something or pay for a service. They may gain power or influence by having

you as a follower. Their cause may gain publicity the more

followers they acquire. They may want you to believe as they do

because they are convinced their belief is correct.

They may want you to do something for them.

WORDS TO KNOW Anecdote Analogy Appeal Deceit/ deceitful Deceptive

Fallacy Faulty Logic Premise Specious

MAKING A LOGICAL ARGUMENT Deductive arguments are supposed

to be water-tight. For a deductive argument to be a good one (to be “valid”) it must be absolutely impossible for both its premises to be true and its conclusion to be false.

Any deductive argument that fails to meet this (very high) standard commits a logical error, and so, technically, is a fallacy.

This includes many arguments that we would usually accept as good arguments, arguments that make their conclusions highly probable, but not certain. Arguments of this kind, arguments that aren’t deductively valid, are said to commit a “formal fallacy”.

The classic example of a deductively valid argument is:

(1) All men are mortal.(2) Socrates is a man.Therefore:(3) Socrates is mortal.

It is simply not possible that both (1) and (2) are true and (3) is false, so this argument is deductively valid.

TYPES OF FAULTY ARGUMENTS Ad hoc, ergo propter

ad hoc Ad hominem Ad ignorantiam Appeal to wrong

authority Card-stacking

Circular reasoning Either/or fallacy False analogy False authority Inconsistency Personal incredulity Straw man

AD HOC, ERGO AD PROPTER HOC Also called “false causation” This fallacy follows the basic format of: A

preceded B, therefore A caused B, and therefore assumes cause and effect for two events just because they are temporally related (the Latin translates to "after this, therefore because of this").

Example: “My alarm goes off every morning at sunrise,

therefore the sun rises because my alarm goes off.”

AD HOMINEM ATTACKS An ad hominem argument is

any that attempts to counter another’s claims or conclusions by attacking the person, rather than addressing the argument itself.

Example:"Andrea Dworkin has written

several books arguing that pornography harms women. But Dworkin is an ugly, bitter person, so you shouldn't listen to her."

Dworkin's appearance and character have nothing to do with the strength of her argument, so using them as evidence is fallacious.

Ad hominem attacks are also known as “mud-slinging”.

AD IGNORANTIAM An argument from ignorance (“ad

ignoratiam” in Latin). The argument from ignorance basically

states that a specific belief is true because we don’t know that it isn’t true.

Example: "Of course telepathy and other psychic

phenomena do not exist. Nobody has shown any proof that they are real."

APPEAL TO WRONG AUTHORITY YouTube - Mike Huckabee

Ad: "Chuck Norris Approved“ This ad also uses a testimonial wherein the fact

that Chuck Norris is a celebrity is supposed to overrule the fact that he is not an authority on politics.

Chuck Norris uses glittering generalities to discuss Huckabee’s qualifications to be president. Glittering generalities are words of praise for a product or person; using nice words like ‘goodness’ or ‘patriotism’.

CARD-STACKING Manipulating information to make a

product appear better than it is often by unfair comparison or omitting facts.

YouTube - New Mac Ad: VirusesThis can also be considered an example

of a straw man argument or selective evidence.

CIRCULAR REASONINGCircular reasoning occurs when the reasoner begins with what

he or she is trying to end up with.Example: A satisfied citizen says: “Richardson is the most successful

mayor the town has ever had because he's the best mayor of our history.”

The second part of this sentence offers no evidence — it simply repeats the claim that was already presented.  Don’t be fooled into believing that using the word “because” in an argument automatically provides a valid reason.  Be sure to provide clear evidence to support your claims, not a version of the premise (the initial statement in an argument).

EITHER/ OR FALLACY An either/or fallacy occurs when a

speaker makes a claim (usually a premise in an otherwise valid deductive argument) that presents an artificial range of choices.

Example:“Well, it is time for a decision. Will you

contribute $10 to our environmental fund, or are you on the side of environmental destruction?”

FALSE ANALOGY

In an analogy, two objects (or events), A and B are shown to be similar. Then it is argued that since A has property P, so also B must have property P. An analogy fails when the two objects, A and B, are different in a way which affects whether they both have property P.

Example:Students and nails are the same. As it is necessary

to hit nails on the head in order to make them work, the same must be done with students.

FALSE AUTHORITY Appealing to someone who is not an

authority to give an expert opinion. You cannot use yourself as your own authority with total certainty, either. 

Example:A doctor is more qualified to diagnose your

shoulder pain than you are; your teachers are better qualified to evaluate your performance than a student.

FALSE PREMISE The premise (proposition, or assumption) is

not correct, the conclusion drawn may be in error.

Example:If the streets are wet, it has rained recently.

(premise)The streets are wet. (premise)Therefore it has rained recently. (conclusion)

INCONSISTENCY Applying criteria or rules to one belief, claim,

argument, or position but not to others. The fallacy occurs when we accept an

inconsistent set of claims, that is, when we accept a claim that logically conflicts with other claims we hold.

Example:“I’m not racist. Some of my best friends are

white. But I just don’t think that white women love their babies as much as our women do.”

STRAW MAN Arguing against a position which you create

specifically to be easy to argue against, rather than the position actually held by those who oppose your point of view.

Example: "Opposition to the North American Free Trade

Agreement amounts to nothing but opposition to free trade." (Someone can believe in free and open trade and yet still oppose NAFTA.)

PERSONAL INCREDULITY

I cannot explain or understand this, therefore it cannot be true.

Example:I don’t understand what the fossil record

is or means, therefore dinosaurs must be made up.

TYPES OF ARGUMENTS THAT CAN BE MANIPULATED

These types of arguments and evidence can be used, but you should be careful to use them sincerely and carefully

ANECDOTAL EVIDENCE

This kind of evidence involves telling stories of individuals suffering because of a problem related to the topic, or individual examples of incidents that support a claim.

Examples: Story of a woman murdered by a paroled

killer in a state that doesn't have the death penalty.

Story of a teenage girl who died of a heroin overdose and who started using marijuana at age 12.

Story of someone who died of a treatable disease after waiting several months for a routine procedure in a country with nationalized health care.

Story of a college student in a country with a low drinking age who does not abuse alcohol.

APPEALS TO LOGIC USING EXPERT OPINION Intentionally failing to use information

suspected of being relevant and significant is committing the fallacy of suppressed evidence. This usually occurs when the information counts against one’s own conclusion.

Perhaps the arguer is not mentioning that experts have recently objected to one of his premises. The fallacy is a kind of fallacy of selective attention--- improperly focusing attention on certain things and ignoring others.

APPEALS TO LOGIC USING STATISTICS 73% of all statistics are made up. Insufficient Statistics--drawing a statistical

conclusion from a set of data that is clearly too small.

Example: A pollster interviews ten London voters in one

building about which candidate for mayor they support, and upon finding that Churchill receives support from six of the ten, declares that Churchill has the majority support of London voters.

EMOTIONAL APPEAL YouTube - Christine O'Donnell ad This ad also uses a “Plain Folks” appeal

which appeals to regular people's values like family, patriotism, and their sense of distrust of the powerful and influential.

It is your job as a careful read and a thoughtful writer to identify them when

someone is working to persuade you and avoid using them when you are trying to

persuade others.

THERE ARE MANY MORE TYPES OF DECEPTIVE, ILLOGICAL,

AND POORLY CONSTRUCTED ARGUMENTS