Informal Fallacies

BASACHANYUNGCO

LEESY

TAN

Informal Fallacies

Objective

IDENTIFY AND AVOID

…

Argumentum ad hominem

Argumentum ad baculum

Argumentum ad ignorantiam

Argumentum ad misericordiam

Argumentum ad populum

Argumentum ad vericundiam

Strawman FallacySlippery slope FallacyRed herring Fallacy False Analogy FallacyFallacy of Complex

QuestionFallacy of Petitio

PrincipiiFallacy of False

Dilemma

ARGUMENTUM AD HOMINEM

- “argument directed to the person” - happens when you reject an argument by

attacking the person who offered it – either in pointing out a character flaw or evil intentions to destroy his credibility

Master Says:An argument must stand or fall on its own

merit, who composed it is irrelevant.

ARGUMENTUM AD HOMINEM

1. You can't believe Dan when he says the proposed policy would help the economy. He doesn't even have a job.

2. Candidate Jane's proposal about zoning is ridiculous. She was caught cheating on her taxes in 2003.

3. Jeff's argument on LeBron James' failures in the NBA finals aren't worth reading, everyone knows he is a "LeBron" hater.

Remember: Gratuitous verbal abuse or "name-calling" itself is not an ad hominem or a logical fallacy. In order to become a fallacy, the insult would need to be given as a reason for believing some conclusion.

ARGUMENTUM AD BACULUM

- argument that appeals to force- uses threat, intimidation and strong-arm

tactics to reject the argument- an argument where force, coercion, or

the threat of force, is given as a justification for a conclusion


1. Employee: I do not think the company should invest its money into this project.Employer: Be quiet or you will be fired.

2. Student: I do not think it is fair that the deadline for our essay is so soon.Teacher: Do not argue with me or I will send you to detention.


An ad baculum argument is fallacious when the punishment is not logically related to the conclusion being drawn. Many ad baculum arguments are not.

If you drive while drunk, you will be put in jail.You want to avoid going to jail.Therefore you should not drive while drunk.

The above argument would become a fallacious Ad Baculum if the conclusion stated:

Therefore you will not drive while drunk.

ARGUMENTUM AD IGNORANTIAM

- argument from ignorance- asserts that a proposition is true because it has not

been proven false (or vice versa)- represents a type of false dichotomy in that it

excludes a 3rd option, which is that there is insufficient investigation and therefore insufficient information to prove the proposition to be either true or false.

Master Says:Just because nobody has disproved the existence of something, doesn’t mean it’s true. If someone wants to prove the truth of something, the burden of proof is in their court.

ARGUMENTUM AD IGNORANTIAM

1. God exists because there hasn't been any conclusive proof to the contrary.

2. No concrete evidence has been revealed regarding UFOs therefore they cannot exist.

3. Since the class has no questions concerning the topics discussed in class, the class is ready for a test.

ARGUMENTUM AD MISERICORDIAM

- argument that appeals to pity- a fallacy in which someone tries to win

support for an argument or idea by exploiting his or her opponent's feelings of pity or guilt

- a specific kind of appeal to emotion

ARGUMENTUM AD MISERICORDIAM

1. You must have graded my exam incorrectly. I studied very hard for weeks specifically because I knew my career depended on getting a good grade. If you give me a failing grade I'm ruined!

2. What do you mean I can't get a job here? All my friends work here! This is unfair! You're going to make me cry. How could you do this to me?

ARGUMENTUM AD POPULUM

- argument that appeals to popularity and traditional institution

- a fallacious argument that concludes a proposition to be true because many or most people believe it; it alleges

- "If many believe so, it is so."

ARGUMENTUM AD POPULUM

1. In a court of law, the jury votes by majority; therefore they will always make the correct decision.

2. Find me anyone who shares your preposterous notion that the Sun orbits the Earth!

ARGUMENTUM AD VERICUNDIAM

- argument that appeals to authority - a special type of inductive argument which often

takes the form of a statistical syllogism- although possible for the argument from authority

to constitute a strong inductive argument, arguments from authority are commonly used in a fallacious manner

Master Says:Not all appeal to authority is fallacious. It is fallacious when it is the wrong authority.

ARGUMENTUM AD VERICUNDIAM

1. My mom said that if the wind blows when my eyes are crossed, they will stay that way. Therefore I must not cross my eyes.

2. My friend will not agree with your diet advice therefore, you're wrong.

STRAWMAN FALLACY

- when an argument is deliberately misrepresented to weaken it

- creating a strawman and passing it as the genuine argument

- to create the illusion of having refuted a proposition by replacing it with a superficially similar yet unequivalent proposition and refuting it, without ever having actually refuted the original position

STRAWMAN FALLACY

1. Agua: The rules on alcohol consumption in the U.P. campus should be reconsidered. Bendita: Of course not! Unrestricted access to those substances will make U.P. a beerhouse!

2. Agua: We should spend our money wisely.Bendita: Wala kang class spirit kasi ayaw mo mag-donate sa LadyMed.

SLIPPERY SLOPE FALLACY

- argument that proposes a long series of intermediate events as the mechanism of connection leading from A to B

- heart of the fallacy lies in abusing the intuitively appreciable transitivity of implication, claiming that A leads to B, B leads to C, C leads to D etc., until one finally claims that A leads to Z

- while formally valid when the premises are taken as a given, each of those contingencies needs to be factually established before the relevant conclusion can be drawn

Master Says:There is no evidence that, if we take the first step, all the predicted consequences to the gruesome end will follow.

RED HERRING FALLACY

- a fallacy in which an irrelevant topic is presented in order to divert attention from the original issue

- a deliberate attempt to divert a process of enquiry by changing the subject

FALSE ANALOGY FALLACY

- an informal fallacy applying to inductive arguments

- often mistakenly considered to be a formal fallacy, but it is not, because a false analogy consists of an error in the substance of an argument (the content of the analogy itself), not an error in the logical structure of the argument

FALLACY OF COMPLEX QUESTION

- the fallacy of phrasing a question that, by the way it is worded, assumes something not contextually granted, assumes something not true, or assumes a false dichotomy

FALLACY OF COMPLEX QUESTION

Have you stopped cheating on exams?

Where did you hide the cookies you stole?

FALLACY OF PETITIO PRINCIPII

- type of logical fallacy in which the proposition to be proven is assumed implicitly or explicitly in the premise

- the fallacy of assuming as a premise a statement which has the same meaning as the conclusion

- not that the inference is invalid (because any statement is indeed equivalent to itself), but that the argument can be deceptive.

- premise must have a different source of reason, ground or evidence for its truth from that of the conclusion.

FALLACY OF PETITIO PRINCIPII

1. Since I'm not lying, it follows that I'm telling the truth.

2. We know that God exists, since the Bible says God exists. What the Bible says must be true, since God wrote it and God never lies.

FALLACY OF FALSE DILEMMA

- a type of logical fallacy that involves a situation in which only two alternatives are considered, when in fact there are additional options (sometimes shades of grey between the extremes)

- can arise intentionally, when fallacy is used in an attempt to force a choice ("If you are not with us, you are against us.")

- can also arise simply by accidental omission of additional options rather than by deliberate deception


Either we ban boxing or hundreds of young men will

be senselessly killed.


A third alternative is to change boxing's rules or

equipment.

NON SEQUITUR

- All fallacious arguments share one thing: the conclusion does not follow from the premise set

- the conclusion could be either true or false, but the argument is fallacious because there is a disconnection between the premise and the conclusion

- Non sequitur = blanket term

Master Says:If you suspect a fallacy, and you have forgotten the name,

call it a non sequitur.

FIN

Informal Fallacies

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