Review from Last Class
• The most used fallacy on Earth!
– Ad Hominem
• Several Types of Ad Hominem
Fallacies
1.
2.
3.
4.
5.
Personal Attack Ad Hominem
Inconsistency Ad Hominem
Circumstantial Ad Hominem
Poisoning the Well
Positive
6. Genetic
Review from Last Class
Beyond attacking the source…
7. Straw Man
“Do I want the police department to take charge of writing
parking tickets? You mean, do I want to get shot if I pull up
next to a fire hydrant? What do you think?”
8. False Dilemma
“Are you kidding me? Either we get another department to
write parking tickets or we’ll start getting shot when we pull
up to a fire hydrant.”
Fallacies
#9. False Dilemma – Special Type: Perfectionist
Believing something is either perfect or must be
rejected.
What’s wrong with this reasoning?
“It’s impossible to eliminate terrorism entirely.
We should stop wasting money on it.”
Can you think of (or make up) others?
Fallacies
#10. False Dilemma – Special Type: Line-Drawing
Believing that either there is a precise place to
draw a line or there is no line to be drawn.
What’s wrong with this reasoning?
“ There shouldn’t be restrictions on violence in
the movies. After all, when is a movie ‘too
violent’? You can’t draw a line.”
Can you think of (or make up) others?
Fallacies
What’s wrong with this argument?
“No, I don’t believe in ‘three strikes and you’re out
for convicted felons. Next thing it will be two
strikes, then one strike. Then we will be sticking
people in jail for life for misdemeanors. It’s not
good policy.”
Issue:
Whether three strikes and you’re out is a good policy.
Conclusion:
No, it’s not.
Premise:
Three strikes and you’re out will lead to jail for life for
misdemeanors.
Fallacies
#11. Slippery Slope
When it is assumed that some event must inevitably
follow from some other event.
“No, I don’t believe in ‘three strikes and you’re out for
convicted felons. Next thing it will be two strikes,
then one strike. Then we will be sticking people in
jail for life for misdemeanors. It’s not good policy.”
Fallacies
Where is the Slippery Slope Fallacy?
Group Exercise
In groups of 3 to 6
Create examples for the following special types of
fallacies.
(Start with a claim first. Then assign somebody as
the proponent of that claim. Then create the
fallacy.)
•
•
•
•
•
•
Personal Attack Ad Hominem
Inconsistency Ad Hominem
Circumstantial Ad Hominem
Poisoning the Well Ad Hominem
Positive Ad Hominem
Genetic
Group Exercise
In groups of 3 to 6
Create examples for the following special types of
fallacies.
(Start with a claim first. Then create the fallacy.)
•
•
•
•
•
Straw Man
False Dilemma
Perfectionist Fallacy
Line-Drawing Fallacy
Slippery Slope
Fallacies
What’s wrong with this argument?
Bill: "I think that Mr. Galindo has psychic powers."
Jill: “No way. What’s your proof?
Bill: “Can you prove that he doesn’t have psychic
powers?
Issue:
Whether Mr. Galindo have psychic powers.
Conclusion:
Yes. Mr. Galindo has psychic powers.
Premise:
??
Fallacies
#12. Misplacing the Burden of Proof
When the burden of proof is placed on the wrong side
of an issue.
(The “why not” or “prove it isn’t true” premise.)
So how do we know which side of the issue
has the burden of proof?
Fallacies
So how do we know which side of the issue has
the burden of proof?
1. The side that has less initial plausibility.
Jim: I think I got a raise today because I have an
invisible good luck unicorn living in my bathroom
Kate: What? No way.
Jim: Hey, can you prove that it’s not true?
Fallacies
So how do we know which side of the issue has
the burden of proof?
2. Affirmative side, if all things are equal.
Jane: High school graduates would be
(affirmative) better off going straight to work
rather than going to college.
Marcia: Why?
Jane: Prove that they wouldn’t be (negative)
better off!
Fallacies
So how do we know which side of the issue has
the burden of proof?
3. Special Circumstances (decided at the outset)
Example
Criminal Court “Innocent until proven guilty.”
Fallacies
#13. Misplacing the Burden of Proof – Special
Case: Appeal to Ignorance.
“We should believe it because nobody has proved
it isn’t so.”
Example:
Bill: "I think that Mr. Galindo has psychic powers."
Jill: "What is your proof?"
Bill: "No one has been able to prove that he
doesn’t have psychic powers."
Fallacies
What wrong
with this
argument?
Fallacies
#14. Begging the Question (circular reasoning)
Using premises that already assume the
conclusion is true.
http://www.colbertnation.com/the-colbert-report-videos/405668/january-10-2012/tip-wag--irresponsible-dead-people---insensitive-papa-john-s
https://showyou.com/v/h-9aptNB25Rqx-56wx/tipwag-irresponsible-dead-people-insensitive-papa-johns
Interviewer: "Your resume looks impressive but I
need another reference.“
Bill: "Jill can give me a good reference.“
Interviewer: "Good. But how do I know that Jill is
trustworthy?“
Bill: “That’s easy! I can vouch for her."
Group Exercise
In groups of 3 to 6
Create examples for the following special types of
fallacies.
(Start with a claim first. Then assign somebody as
the proponent of that claim. Then create the
fallacy.)
•Personal Attack Ad Hominem
•Inconsistency Ad Hominem
•Circumstantial Ad Hominem
•Poisoning the Well Ad Hominem
•Positive Ad Hominem
•Genetic
Group Exercise
In groups of 3 to 6
Create examples for the following special types of
fallacies.
(Start with a claim first. Then create the fallacy.)
•Straw Man
•False Dilemma
•Perfectionist Fallacy
•Line-Drawing Fallacy
•Slippery Slope
•Misplacing the Burden of Proof
•Appeal to Ignorance
•Begging the Question
Group
Exercise 7-3 #2, 3, 4, 6, 9
2. Perfectionist Fallacy
3. False Dilemma
4. Straw Man
6. Poisoning the Well
9. Begging the Question