This document defines opinion and argument, and discusses common fallacies to avoid in forming opinions. It states that an opinion is a person's judgment about something that requires justification, while an argument consists of a claim supported by premises. The document then defines fallacies as faulty arguments, and provides examples of 10 common fallacies: ad hominem, ad populum, appeal to authority, begging the question, false dichotomy, hasty generalization, post hoc, missing the point, spotlight fallacy, and straw man. It emphasizes avoiding fallacies in forming well-reasoned opinions.

1. OPINION
AND COMMON FALLACIES
Prepared by:
MR. ANTONIO T. DELGADO
Faculty, General De Jesus College

2. FOCUS QUESTIONS
1. What is opinion?
2. What is argument? What are its parts?
3. What are fallacies?
4. Why is it important to avoid fallacies in forming
opinion?
2

3. OPINION
▪ It is a statement of judgment of a person about
something in the world.
▪ It is a statement of judgment that is in need of
further justification.
3

4. 4

5. “
Walang maling opinyon.
5

6. “
Akala mo lang wala…
6

7. “
…pero meron!
7

8. “
“Opinyon ko na
dapat mamatay
na tayong lahat.”

9. “
9

10. ARGUMENT
▪ It is a group of statements that serve to support a
conclusion.
▪ It is made up of a claim (the conclusion of an
argument) and premises (the reasons used to
support the conclusion).
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11. ARGUMENT
▪ Not all arguments are good arguments.
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12. 12

13. 13

14. 14

15. FALLACIES
▪ We call fake arguments “fallacies”.
▪ Fallacies are groups of statements that appear to
be arguments, but fail to support the conclusion.
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16. 16

17. 17

18. AD BACULUM
This occurs when one appeals
to force or the threat of force to bring about
the acceptance of a conclusion.

19. COMMON
FALLACIES
19

20. 1.
AD HOMINEM
This occurs when an author attacks his
opponent instead of his opponent’s argument.

21. Ad Hominem
▪ Trina thinks guns should be outlawed but Trina
doesn’t go to church, so we shouldn’t listen to her.
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26. 2.
AD POPULUM
It attempts to prove an argument as correct
simply because many people believe it to be so.

27. Ad Populum/ Bandwagon
▪ 80% of people are for the death penalty, therefore,
the death penalty is moral.
27

28. 28

29. 3.
APPEAL TO AUTHORITY
The author claims his argument is right because
someone famous or powerful supports it.

30. Appeal to Authority
▪ We should change the
drinking age because
Einstein believed that
18 was the proper
drinking age.
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31. 4.
BEGGING THE QUESTION
This happens when the author’s premise and
conclusion say the same thing.

32. Begging the Question
▪ Fashion magazines don’t
hurt women’s self-esteem
because women’s
confidence is intact after
reading the magazine.
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33. 5.
FALSE DICHOTOMY
This fallacy rests on the assumption that there
are only two possible solutions.

34. False Dichotomy
▪ The teacher gives too many 90’s and therefore
must be fired because grade inflation is unfair to
other students.
34

35. 6.
HASTY GENERALIZATION
It occurs when the proponent uses too small of a
sample size to support a sweeping generalization.

36. Hasty Generalization
▪ Sally couldn’t find any cute clothes at the boutique
and neither could Maura, so the boutique doesn’t
have any cute clothes.
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37. 37

38. 38

39. 7.
POST HOC
This fallacy assumes that correlation
equals causation.

40. Post Hoc/ False Cause
▪ The chess team gets better grades than the
basketball team, therefore playing chess makes
you smarter than playing basketball.
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41. 8.
MISSING THE POINT
It occurs when the premise of the argument supports a
specific conclusion but not the one the author draws.

42. Missing the Point
▪ Antidepressants are overly prescribed which is
dangerous, so they should clearly be made illegal.
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43. 9.
SPOTLIGHT FALLACY
It occurs when the author assumes that the cases that
receive the most publicity are the most common cases.

44. Spotlight Fallacy
▪ 90% of news reports talk about negative events.
Therefore, it follows that 90% of events that occur
in the real world are negative.
44

45. 20,000
Number of extrajudicial killings according to human rights groups
45

46. 46

47. “This is the front-page photo in the Philippine Daily
Inquirer’s July 24, 2016 issue showing pedicab
driver Michael Siaron’s lifeless body being cradled
in a Pieta-like pose by his partner. Siaron, the
newspaper claimed,* was executed by the police in
the course of President Duterte’s war against illegal
drugs. The photo went viral on the internet, with
Western newspapers publishing it on their own front
pages.
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48. “
It turns out now, after more than a year of police
investigation, that the pedicab driver was killed by a
drug syndicate’s assassin, one Nesty Santiago,
who was also responsible for five other killings. The
unique scratches – like fingerprints – on the bullets
that murdered Siaron matched with the gun used by
the killer, recovered when he was killed in
December.
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49. 10.
STRAW MAN
The author puts forth one of his opponent’s weaker,
less central arguments forward and destroys it, while
acting like this argument is the crux of the issue.

50. Straw Man
▪ My opponent wants to increase teachers’ pay but
studies have shown that professors with tenure
don’t work as hard at their job to improve
themselves.
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51. EVALUATION
1. What is opinion?
2. What is argument? What are its parts?
3. What are fallacies?
4. Why is it important to avoid fallacies in forming
opinion?
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52. “
“Everyone is entitled
to his own opinion...”

53. 53

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55. THANKS!
ANY QUESTIONS?
PowerPoint presentations are available at:
▪ www.facebook.com/GJCphilo

56. REFERENCES
1. Skoskiewicz, M. (May 22, 2011). 10 Common
Logical Fallacies. Retrieved May 17, 2018, from
https://www.myguruedge.com/our-
thinking/myguru-blog/bid/214477/10-common-
logical-fallacies
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