Informal Fallacies
BASA
CHANYUNGCO
LEE
SY
TAN
Objective
IDENTIFY AND
AVOID …
 Argumentum ad hominem  Strawman Fallacy
 Argumentum ad baculum  Slippery slope Fallacy
 Argumentum ad
 Red herring Fallacy
ignorantiam
 False Analogy Fallacy
 Argumentum ad
 Fallacy of Complex
misericordiam
Question
 Argumentum ad populum  Fallacy of Petitio Principii
 Argumentum ad
 Fallacy of False Dilemma
vericundiam
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
ARGUMENTUM AD BACULUM
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.
ARGUMENTUM AD BACULUM
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 magdonate 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
FALLACY OF FALSE DILEMMA
Either we ban boxing or
hundreds of young men will be
senselessly killed.
FALLACY OF FALSE DILEMMA
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