This is a discussion about Ad Hominem Fallacies and Appeal to autority

2. FALLACIES IN
CRITICAL
THINKING
Joanne Marie A. Urbano
Phd Mathematics Education

3. What is Fallacy?
● Fallacies are defects that weaken arguments.
● First, fallacious arguments are very, very common and can be quite
persuasive, at least to the causal reader or listener. You can find
dozens of examples of fallacious reasoning in newspapers,
advertisements, and other sources.
● Second, it is sometimes hard to evaluate whether an argument is
fallacious.
● An argument might be very weak, somewhat weak, somewhat
strong, or very strong. An argument that has several stages or parts
might have some strong sections and some weak ones.

4. ● Fallacies are flaws in the way reasoning and
evidence is used in an argument.
● Sometimes peoaple are intentionally fallacious in
order to manipulate, and sometimes they are not
aware of their fallacies.
● As critical thinkers, we must learn to recognize
these fallacies—especially in the media, in politics,
with your professors, peers, or anyone else who
tries to influence/persuade you.
Definition of Fallacy

5. Faulty logic and
arguments often
appear to be correct.
Informal Fallacies Formal Fallacies
Arguments that are flawed because of
mistaken assumptions in the premises,
errors in language, misuse of evidence,
or violation of argument principles.
.
These occur because of
mistakes in the logical
structure of the argument in
terms of syllogisms.

6. AD HOMINEM
"Against the man"

7. AD HOMINEM
● attacking the arguer rather than the
argument; discrediting an argument by
trashing the person making it.
● Watch for this is EVERY political debate!
● Marked by or being an attack on an
opponent's character rather than by an
answer to the contentions made.

8. AD HOMINEM
● ‘Ad hominem’ is Latin for ‘to the man,’ and the idea
in this kind of fallacy is that criticisms are directed
towards the person rather than to the person’s
thoughts about or arguments for a particular view.
● Ad hominem reasoning is fallacious since
logically, the faults of the person are one thing
and the defects in what he or she says are quite
another.
● The faults of the individual don’t automatically
attach themselves to what he or she says.

10. There isn’t just one type of ad hominem fallacy. Let’s look at the
different types of ad hominem arguments you might find.
•Abusive - This is where the person is directly attacked. (i.e. This is
why a woman shouldn’t do a man's job.)
•Circumstantial - Personal circumstances motivate a person's
argument, so it must be false. (i.e. This car is proven to get great gas
mileage. Yeah right! You just want my sale.)
•Guilt by Association - Due to an association to something negative,
an argument is discredited. (i.e. Pol Pot was evil and against religion.
All people against religion are bad.)
•Tu Quoque - Past actions discredit your argument. (i.e. You don’t
believe that cheating is bad when you cheated on your wife.)

11. PERSONALATTACK AD HOMINEMS
● Disliking either a person or something negative
about him, and finding critically acceptable
reasons to reject a claim that he makes are two
different things.
● We commit the error or fallacy of reasoning
called ‘ad hominem’ when we reject a person’s
claim merely because we dislike the person or
something about the person.

12. PERSONALATTACK AD HOMINEMS
○ This version of ad hominem is called
personal attack.
○ Because we simply reject a claim made by a
person or group because we dislike the
person or group, personal attack ad
hominem pseudoreasoning is much more
emotional or psychological than it is rational
or logical.

13. PERSONAL ATTACK AD HOMINEMS
● If we think that a person’s negative characteristics are
relevant to rejecting a claim she makes, then it may be
plausible to reject the claim.
○ However, we must be able to explain the relation of those
characteristics to the claim being made so that rejecting the
claim for this reason can be made plausible.
○ For instance, if we know that a person x is a hater of another
class of people y, then any negative claim about y made by x
may be reasonably regarded as being suspicious and likely to
be false.
○ Thus, further information may be needed to assess the claim
accurately.

15. CIRCUMSTANTIAL AD HOMINEMS
● Circumstantial ad hominem =df. A fallacy in which
a person’s claim is rejected based upon the
circumstances of the person making the claim.
● In circumstantial ad hominem the attack is not on
the person, but her circumstances, and it is inferred
that a claim made by the person is false because
someone in her position or circumstances would
make such a claim.

16. CIRCUMSTANTIAL AD HOMINEMS
○ For instance, thinking that a tax cut proposed by a
wealthy congressman cannot be good for the average
person because of his position of wealth is a
circumstantial ad hominem.
○ Rejecting Bill’s arguments against the death penalty
because he is sitting on death row is also circumstantial
ad hominem.
● Personal attack and circumstantial ad hominems
overlap, and trying to distinguish between them in
particular instances can be pointless.
● The main thing to recognize is that, if it is an ad
hominem, then it is fallacious.

18. PSEUDO REFUTATION
● Psedo refutation =df. A type of ad hominem
based on charges of inconsistency where no
relevant inconsistency exists.
● Relevant inconsistencies are inconsistencies
between claims.
● if Jane says that it is both snowing and not
snowing at the same time in the same place,
then we can reject her claim as logically
inconsistent.
● .

19. PSEUDO REFUTATION
● But if there are no inconsistencies between claims then
the fact that a person may not act (or may not always have
acted) as if the claim is true does not allow us to infer that
the claim is false or even that the person thinks it is.
○ For instance, we cannot reject Jane’s claim to love Jim
simply by noting that she has never acted as if she
loved Jim.
○ And we can’t then infer that she herself believes her
claim about her love for Jim to be false. Either would
be pseudo refutation.

20. ● We must also recognize that a person
can change his mind.
○ Thus, a person does not contradict herself by now
agreeing with the morality of euthanasia when she
earlier rejected it.
○ To say that this is contradictory is pseudorefutation.

21. “POSITIVE”AD HOMINEM
● To this point we have looked at ad hominem
arguments in relations to something negative about a
person, and have seen that, in abusive or personal
attack ad hominem, a person’s claim is rejected
merely because we dislike the person or something
about the person.
● However, it is also fallacious to accept an argument
merely we like the person or something about the
person.

22. “POSITIVE”AD HOMINEM
● This form of pseudo reasoning does not have
a name in the literature, but it is an ad
hominem because a person’s claim is
accepted, not on the basis of critically
acceptable arguments, but because of an
agreeable characteristic(s) which the person
has.
● Accordingly, it is once again emotional or
psychological rather than rational or logical.

23. “POSITIVE”AD HOMINEM
● However, as before with negative characteristics, if we think that a
positive characteristic(s) of a person is relevant to accepting a
claim she makes, then it may be plausible to accept the claim.
● However, we must be able to explain the relation of those
characteristics to the claim being made so that accepting the
claim for this reason can be made plausible.
○ For instance, if we know that Jane is a lover of classical music, and
her love has made her listen carefully and extensively to such music,
then a claim which she makes about the worth of a particular classical
composition might be accepted hypothetically as likely to be true, at
the same time that further information may be needed to assess

24. EXAMPLE
Sam: "I believe that abortion is morally wrong."
Jessica: "Of course you would say that, you're a priest."
Sam: "What about the arguments I gave to support my
position?"
Jessica: "Those don't count. Like I said, you're a priest, so
you have to say that abortion is wrong. Further, you are just
a lackey to the Pope, so I can't believe what you say."

25. EXPLANATION
Jessica is attacking Sam because he is a
priest rather than the argument he uses to
support the fact that abortion is wrong.
Dave says that he has to believe that
because he is a priest.

26. EXAMPLE
Dear Editor, The current campaign against combining drinking with
driving is terrorising law-abiding people. Many law-abiding people
are cutting their alcohol consumption because they are afraid of
being caught by random breath testing. But research shows that
the average drink-driver in a fatal accident has an average blood
alcohol level of more than twice the legal limit. The current
campaign against drinking and driving is failing to achieve what
should be our top priority; getting the heavy and hardened
drinkers of the road.” Douglas Myers. CEO, Dominion Breweries.

27. EXPLANATION
“Dear Editor, I read Doug Myer’s letter yesterday but
he is the CEO of a major brewing company! He
has a vested interest in keeping alcohol sales up,
and the anti-drink-driving campaign threatens to
reduce alcohol sales. We shouldn’t take any
notice of his views about drinking and driving”.

29. In Political Debates
Have you ever watched a presidential debate? Boy, can
they get ugly. Some politicians have even been known to
resort to name-calling. Things certainly get sticky in the
political arena; here are a few examples to that effect.
•Degrading another politician during a campaign when
asked about a specific policy - "Well, I think we need to
look at Senator Smith's failures regarding this issue."
•Responding in any debate with an attack on one's
personal beliefs - "You don't even belong to a church. How
can you claim to be a Christian?"

30. •Generalizing views of a political party as an
insulting argument to an individual who is a
member of a different party - "Well, it's pretty
obvious that your political party doesn't know
how to be fiscally responsible, so I wouldn't
expect you to be either.“
•Attacking an opponent's physical attractiveness
rather than looking at the faults in their politics -
“Just look at that face! How could anyone vote
for that?”

31. In Everyday Life
A simple conversation can suddenly take a left turn into ad
hominem territory. Something very innocent can inadvertently
become a personal attack on someone else. Let's take a look at a
few more examples so you can keep your ad hominem detective
skills on point.
•Using someone's education level as a means to exploit and
degrade the opposer's argument - "You didn't even finish high
school. How could you possibly know about this?“
•Demeaning a teacher's decision on grading by insulting her
intelligence - "Well, it's not like you graduated from a good school,
so I can see why you wouldn't know how to properly grade a
writing assignment."

32. •Stating that one's age precludes him from being able
to make an intelligent or meaningful argument - "You're
clearly just too young to understand.“
•Use of marital status to invalidate an opinion of
someone of a different status - "How can you make a
decision about someone having marital problems if
you've never been married yourself?"
•Stating that the ethnicity of the opposing individual
keeps him from formulating a valuable opinion - "You
are from the United States, so you could never
understand what it's like to live in a country like that."

33. Used in Media
•Whether it’s an opinion piece or lively on-air discussion, words can
easily get personal. Explore some different examples that attack
religion, sexual orientation, and even socioeconomic status.
•Attacking someone's own sexual orientation in arguing about the
right of LGBT individuals to marry - "The only reason you could
possibly be in favor of this is because you're not being honest
about your own sexuality."
•Using someone's known background or beliefs - "Of course you
would say that. You believe life begins at conception and have
never studied alternative facts."

34. •Stating that someone's argument is incorrect because
of her religious beliefs - "Perhaps if you weren't
Mormon, you would see this quite differently."
•Relying on socioeconomic status as a means to
undermine an opposing individual's opinion - "You
wouldn't understand since you have never had to
struggle."
•Using gender as a means to devalue an argument from
an opposing gender - "This is a female issue. As a man,
how can you have an opinion about this?"

35. APPEAL TO
AUTHORITY
(AD VERICUNDIAM)

36. Fallacious appeals to authority take the general form of:
1. Person (or people) P makes claim X. Therefore, X is true.
A fundamental reason why the Appeal to Authority can be
a fallacy is that a proposition can be well supported only
by facts and logically valid inferences. But by using an
authority, the argument is relying upon testimony, not
facts. A testimony is not an argument, and it is not a fact.

37. When we appeal to authority, we claim the
truth of a proposition is guaranteed because
of the opinion of a famous person.
Appeals to authority look like this:
Authority figure X says Y. Therefore, Y is true.

38. Appeal to authority is a common type of fallacy, or an
argument based on unsound logic.
When writers or speakers use appeal to authority, they
are claiming that something must be true because it is
believed by someone who said to be an "authority" on the
subject.
Whether the person is actually an authority or not, the
logic is unsound. Instead of presenting actual evidence,
the argument just relies on the credibility of the
"authority."

39. Types of Appeal to Authority
The different types of the Appeal to Authority are:
1. Legitimate Appeal to Authority
2. Appeal to Unqualified Authority
3. Appeal to Anonymous Authority

40. Legitimate Appeal to Authority
Legitimate appeals to authority involve testimony from individuals who are
truly experts in their fields and are giving advice that is within the realm of
their expertise, such as a real estate lawyer giving advice about real estate
law, or a physician giving a patient medical advice.
We must keep in mind that for such an appeal to be justified, certain
standards must be met:
1. The authority is an expert in the area of knowledge under consideration.
2. The statement of the authority concerns his or her area of mastery.
3. There is agreement among experts in the area of knowledge under
consideration.

41. Example: Legitimate Appeal to Authority
1. My doctor has said that medicine X will help my medical
condition. Therefore, it will help me with my medical
condition.
2. Richard Dawkins, an evolutionary biologist and perhaps
the foremost expert in the field, says that evolution is true.
Therefore, it's true.

42. Appeal to Unqualified Authority
Alternative Names:
Argumentum ad Verecundiam
The Appeal to Unqualified Authority may look like a Legitimate
Appeal to Authority, but it is not. The "authority" in this case may be
giving advice or testimony that is outside of their realm of expertise,
such as a person who suffers from a disease testifying about the
causes of that ailment even though they are not a doctor, or even a
doctor testifying about a medical issue that is actually outside of
their specialty or area of expertise.

43. An Appeal to an Unqualified Authority looks much like a
legitimate appeal to authority, but it violates at least one
of the three necessary conditions for such an appeal to be
legitimate:
1. The authority is an expert in the area of knowledge
under consideration.
2. The statement of the authority concerns his or her area
of mastery.
3. There is agreement among experts in the area of
knowledge under consideration.

44. Example: APPEAL TO UNQUALIFIED AUTHORITY
1. My favorite actor, who appeared in a movie about AIDS, has testified
that the HIV virus doesn’t really cause AIDS and that there has been
a cover-up. So, I think that AIDS must be caused by something other
than HIV and the drug companies are hiding it so that they can make
money from expensive anti-HIV drugs.
2. A commercial claims that a specific brand of cereal is the best way
to start the day because athlete Michael Jordan says that it is what
he eats every day for breakfast.

45. Appeal to Anonymous Authority
Alternative Names:
Hearsay - information received from other people
that one cannot adequately substantiate; gossip
Appeal to Rumor
The Appeal to Anonymous Authority is, essentially,
giving testimony or advice that refers to unnamed
sources, such as making a statement based on what
"experts" say or what "historians" contend, without
ever naming the sources. This calls into question the
validity of the testimony.

46. Arguments in Scientific Matters
We often see the Appeal to Anonymous Authority used in
arguments where scientific matters are at question:
1. Scientists have found that eating cooked meat causes
cancer.
2. Most doctors agree that people in America take too
many unnecessary drugs.
3. According to government experts, the new nuclear
storage facility poses no dangers.

47. 4. Environmental experts have demonstrated that
global warming does not really exist.
5. Every open-minded historian will agree that the
Bible is relatively historically accurate and that
Jesus existed.
6. I know a chemist who is an expert in his field,
and according to him evolution is nonsense.
7. They say that crime is increasing because of a lax
court system.

48. EXAMPLES OF APPEAL TO
AUTHORITY FALLACY:
1. A book argues that global warming is not
actually happening, and cites the research
of one environmental scientist who has been
studying climate change for several years.
2. Someone argues that drinking is morally
wrong and cites a sermon from her pastor
at church.

49. EXAMPLES OF APPEAL TO AUTHORITY FALLACY:
3. A little boy says that his friends should not go swimming
in a river because his Mama said there were germs in the
river.
4. A commercial claims that 3 out of 4 dentists would choose
this particular brand of toothpaste for their own families to
use.
5. My sister-in-law, who is a teacher, said that this school is
not somewhere that I would want to send my children.

50. Can you name the
fallacy?
03
Question 3
01
Question 1
02
Question 2
Choose a question:

51. Question 1
A politician arguing that his
opponent cannot possibly be
a good choice for women
because he has a religious
conviction that causes him
to be pro-life.
Ad Hominem Appeal to Authority

52. Question 2
Richard Dawkins, an
evolutionary biologist and
perhaps the foremost expert
in the field, says that
evolution is true. Therefore,
it's true.
Ad Hominem Appeal to Authority

53. Question 3
A mother who tells the
pediatrician that she doesn't
trust his judgment because
he's never been a mother..
Ad Hominem Appeal to Authority

54. Great job!

55. ~ Leonardo da Vinci
“Anyone who conducts an argument by
appealing to authority is not using his
intelligence; he is just using his memory. “

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