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Discourse Fallacies

PSC 202Fall 2004Prof. Northrup

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Formal and Informal Fallacies

FallacyFormal fallacyInformal fallacy

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Informal Fallacies – Four Types

I. Fallacies of Ambiguity

II. Fallacies of Relevance

III. Fallacies of Presumption

IV. Fallacies of Weak Induction

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I. Fallacies of Ambiguity (5)

Based on ambiguous use of terms or phrases

That is, the term or phrase can have more than one meaning

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I. 1) Equivocation

A shift in meaning of a word in one premise to the next, or from a premise to the conclusion

E.g.All cats are small domestic animals

All lions are cats

So, all lions are small domestic animalsCan be done conversationally

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I. 2) Amphiboly

Like equivocation, but applies to a phrase

The meaning of the phrase shiftsExample: Methodists and “doubt”

Leader: Rise and greet the morning.People: Cast off your sleep and doubt.

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I. 3) Accent

Occurs when a passage is incompletely quoted or a passage is taken out of context or both

Examples:Sound bitesTaking only words that support your side

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I. 4) Division

When a claim that is true of an entire class of things is mistakenly applied to a single member of the class, OR

A claim that is true of a whole thing is mistakenly applied to a part of a whole

Example: state vs. national trends

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I. 5) Composition

The mirror image of division Inferring that a whole or an entire class of

objects has certain properties because one of the parts of the whole, or one member of the class, has that property

Examples: “Because of hurricane Ivan, there was flooding

in Louisiana today.” “The hood of my car is red, so my car is red.”

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II. Fallacies of Relevance (8)

Assume a false premise or reach a conclusion that is not supported by the premises

Often used by politicians

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II. 1) Appeal to Force

Argumentum ad baculumAn argument includes an implicit but

unwarranted or inappropriate threatConsider:

“You should make a contribution to the Democratic candidate. After all, you are currently an employee of this company.”

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Appeal to Force - Caveat

Not a fallacy if the threat is legitimateConsider:

“Watch your speed. Police use radar.”

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II. 2) Personal Attack

Argumentum ad hominemOccurs when replying to an argumentThe person, not the argument, is

attackedCalling credibility into question

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Personal Attack continued 1

Tricky – sometimes valid to question E.g. “expert” witness in a trial

Example? Campaign strategy of accusing opponent of flip-flopping

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Personal Attack continued 2

Tu quoque (literally, “you too”) “You do it, why shouldn’t I?”

Sarcasm as a response “I see you've set aside this special time to

humiliate yourself in public.”

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II. 3) Mob Appeal

Argumentum ad populum Assumption that some type of popular appeal

is a sufficient reason to engage in an action or hold a belief

Typical forms Inclusion: “Doing x (e.g. voting for this candidate)

makes you feel good, so you should do it.” Exclusion: Not doing x excludes you from the norm

(of the mob) Appeals to emotion (e.g. Hitler’s speeches) “Family values”?

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II. 4) Appeal to Pity

Argumentum ad misericordium Assumes that suffering is a sufficient reason to

engage in an action or hold a belief (e.g. charity call) Possibly valid moral reason but irrational solution Or may not be a cause for pity

So must ask two questions: Is there moral force to the claim of suffering Is the solution a good one

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II. 5) Stereotyping

General claim about a group that is falsebecause

1. not true of that group There was a blonde, a red-head and a brunette…”

2. not more true of that group than any other “Red-heads have bad tempers”

3. claim has some validity but not of the group’s making Northern Ireland – Protestant claim that Catholics

are lazy because they don’t get jobs Also called the genetic fallacy

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II. 6) Straw Man

When an argument is misrepresented and the misrepresentation is criticizedCan be done by claiming that there is an

underlying premise that you have now revealed, and it’s wrong

Can be done by misrepresenting the conclusion, and then criticizing the conclusion

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II. 7) Red Herring

A response to an argument that confuses the issues, thus causing a distraction from the actual

argumentSmith factory exampleDistraction may be a valid concern, but

doesn’t address the argument at hand

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II. 8) Irrelevant Conclusion

non sequitur (doesn’t follow)When a conclusion is drawn from an

argument not suggested by the premisesObvious example - an invalid deductive

argument:All aardvarks are mammalsAll mammals are vertebratesSo, some aardvarks are good pets

Hunting example

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III. Fallacies of Presumption (4)

Assumes something that isn’t stated and does so incorrectlyassumes the conclusion as a premiseassumes that the premises contain all the

relevant information while they do notUnlike a deductive argument where the

premises entail the conclusion, that is, the premises logically result in the conclusion

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III. 1) Begging the Question

Conclusion is assumed as one of the premises “George Bush is the President because George

Bush is President”

Different words, same meaning “George Bush is the President of the US, since

George Bush holds the highest office in the US”

True, but proves nothing Circular argument: made up of several

arguments where the conclusion of the last is a premise of the first

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III. 2) Complex Question

Assumes a previous question has been answered “How long have you been cheating on tests?”

Question by itself doesn’t constitute a fallacy; has to be part of an argument

An implicit argument can often by found in a question (immigration example)

Caveat: Not a complex question if embedded in a longer argument where the premises are explicitly stated

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III. 3) Suppressed Evidence

When you know there is evidence contrary to your position, yet you suppress the evidence

E.g. tobacco companies

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III. 4) False Dichotomy

Occurs in the case of a disjunctive syllogism (either/or argument)Maria is either a Democrat or RepublicanMaria is not a DemocratSo she is a Republican

If disjunctive premise is false, the conclusion is false

Example: 1950s motto, “Better dead than red”

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IV. Fallacies of Weak Induction

Remember = inductive arguments are probable arguments

Fallacy occurs when insufficient evidence is provided

Weak induction fallacies occur when evidence cited is weak or incompleteevidence contrary to the conclusion is

ignored

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IV. 1) Appeal to Authority

Incorrect use of authorityAssuming authority in one field implies

authority in anotherAppeal to something as an authority (e.g.

custom, popular opinion) when it is not

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IV. 2) Appeal to Ignorance

A claim is made, either that since there isn’t any evidence that a

proposition is false, it must be true, or that since there isn’t any evidence that the

proposition is true, it must be falseNuclear power plant exampleCaveat: Some statements can look like

an appeal to ignorance but aren’t

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IV. 3) Hasty Generalization

When a conclusion is reached on the basis of insufficient evidence

Can happen when a conclusion is drawn from an atypical sample or too small a sample

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IV. 4) False Cause

Something is taken to be a cause when it isn’t (non causa pro causa, “not a cause as a cause”) Advertising tactic

1. One event follows another; first event is identified as the cause (post hoc ergo propter hoc, “before therefore because”) e.g. superstitions

2. Single cause identified but a complex situation Ronald Reagan ended the Cold War

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IV. 5) Slippery Slope

Chain of causal claims with one or more of them false

Often characterized by consequences getting progressively worseCigarettes lead to heroin

Caveat: There are valid causal chainsPolitical issues like gun control - slippery

slope or not?

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IV. 6) Weak Analogy

An argument that uses analogy to persuade, but where there are ways in which the points of

comparison are insufficient to support the claim or

there are significant non-analogous points among the things compared