Transcript Class #8 - 1/30/14

Philosophy 1100
Title:
Critical Reasoning
Instructor:
Paul Dickey
E-mail Address: [email protected]
Website:http://mockingbird.creighton.edu/NCW/dickey.htm
Today:
Final Essay -- Questions?
Chapter 7 Discussion
Start Chapter 8
Next Week:
Portfolio Assignment #6
Read Chapter 8, pp. 253- 261, 264-266.
pp.271-279 & pp. 281-284
Exercise 8-2
1
Portfolio
Assignment #6
What is Rhetoric?
·
“Collect” 2-3 artifacts that illustrate
different forms of rhetoric. For each, write a
description of the artifact selected, identify the
form of rhetoric, and explain why this is an
example of that particular form.
· What are Logical Fallacies?
·
“Collect” 2-3 artifacts that illustrate
different logical fallacies. For each, write a
description of the artifact selected, identify the
type of logical fallacy it is, and explain why this
is an example of that particular logical fallacy.
Chapter Seven
More Fallacies
3
The Ad Hominem Fallacy
•
Maybe the most common of all logical mistakes.
•
The Ad Hominem Fallacy mistakes the qualities of the
argument itself with the the person or personality of the
individual making the claim.
“BOB: Reality consists of more than just what can see and feel.
God is real.
BIKER: “If you weren’t so removed from reality, I might be more
inclined to discuss it with you.”
Want more advanced stuff on topic? Click here
4
The Ad Hominem Fallacy
•
Most ad hominem arguments are negative and
typical examples of ad hominem arguments will
be negative, but not always.
• e.g. Heather is very nice and is always a very positive
person, so if she is opposed to the war in Iraq, there
must be something terribly wrong with it.
•E.g. Ms. Gullible: “The Jehovah Witnesses that come
to the door always seem to be the “sweetest” people so
there must be something to what they believe.”
5
The Personal Attack Ad Hominem
•
Say you twist the example about Heather around.
• e.g. My boss is a very negative person, so
although he is opposed to the war in Iraq, that
means nothing. He is against everything.
Video
• e.g. remember Rush Limbaugh in the video:
“If you are going to start agreeing with Rosie
O’Donnell, I would suggest rehab and
treatment.” (Ridicule & Sasrcasm)
6
Specific Forms of Ad Hominems
•
The Inconsistency Ad Hominem suggests erroneously that if
one can show that a person has made contradictory claims
at different occasions, then the claims are thereby refuted,
e.g. Hilary can’t be right that Obama is ready to be
president as she is saying now. She said exactly the
opposite during her political campaign.
•
The Circumstantial Ad Hominem suggests erroneously that
if one’s claim is associated to the claimant’s circumstances
in life, then the claim is refuted e..g. Of course, Sen. Nelson
is for farm subsidies. He is from Nebraska.
•
Poisoning the Well occurs when an ad hominem is issued
prior to allowing someone to make their argument.
Interestingly, a speaker might have “the well poisoned
against her” by the opponent making a denial of something
unsavory about her, such as “Hilary may not be a bleeding
heart liberal, but….”
Video
7
The Genetic Fallacy (Beth)
•
The Genetic Fallacy suggests erroneously
that a claim is refuted by disputing its origin or
history.
• e.g. The constitution is a bogus document
since it was primarily written with the intent to
protect the property of the wealthy.
• e.g. God does not exist because the whole
idea of God originated with superstitious
people who had no knowledge of science or
the universe.
Want more advanced stuff on topic? Click here
8
The Straw Man or “Straw Figure”
(Keith)
•
The Straw Man Fallacy occurs when a claim
is made that distorts, exaggerates, or
otherwise misinterprets an opponent’s
position such that it becomes easy to refute.
•
e.g. “Congressmen who want us to set a
timetable to leave Iraq are just saying that
we should surrender.”
Important Video
Is this a Straw man Bill Clinton is presenting?
Want more advanced stuff on topic? Click here
9
The False Dilemma (Kaitlyn)
•
The False Dilemma fallacy occurs when you limit
considerations to only two alternatives although other
alternatives may be available.
• e.g. Either we keep all of our current forces in Iraq
until victory or we just pull out now unconditionally and
let the terrorists win. It is either one or the other, dude.
• e.g. You don’t believe in allowing prayer in public
schools? So what are you an atheist?
•
You want this?
OR
THIS?
Want more advanced stuff on topic? Click here
10
The Perfectionist Fallacy
•
A specific type of The False Dilemma is the
Perfectionist Fallacy which suggests that if a policy
or a claim is not perfect then it must be rejected.
• e.g. “If they don’t fit, you must acquit.”
•Johnny Cochran’s defense of O.J.
Simpson, referring to his purported gloves.
• e. g. The National Football League’s instant
replay rule is no good because you are still going
to still have some bad calls.
•The National Football League’s instant replay rule
is no good because they seem to have to make
adjustments to it every year.
11
The Line-Drawing Fallacy
•
Another type of The False Dilemma is the LineDrawing Fallacy which suggests that a distinction
cannot be made because there is no precisely
known, agreed upon point at which a line can be
drawn.
• e.g. In the Rodney King case, when exactly did
the beatings become excessive force?”
• e.g. When did Bill Gates become rich? When he
earned his first dollar? His first $100,000? His first
$1M? $10M? $1B? Nonetheless, I can assure you
that Bill Gates is rich.
12
The Slippery Slope
(Zach)
•
The Slippery Slope Fallacy asserts that we
can’t let one thing happen because it could
lead to something else where there is no
argument or a weak argument that the first
action does in fact lead to the second.
Important Video
• e.g. Making people register hand guns is
just the first step to making guns illegal.
• e.g. Marijuana use should be illegal
because it can lead to harder drugs.
Want more advanced stuff on topic? Click here
13
Misplacing/Shifting
the Burden of Proof (Jake)
•
The burden of proof in an argument rests on the person
making the claim. It is her responsibility to give the
premises and the reasons to believe her claim is true.
•
To try to shift the burden of proof onto the person who is
listening to your argument and trying to make him show
that you are wrong is called misplacing the burden of
proof.
•
A particular example of this logical error is the appeal to
ignorance which suggests that we should believe
something because no one has proven or shown it to be
wrong.
•
Another example is when a proponent of a claim
suggests that his position is right because you haven’t
give a good argument for the opposite claim.
Video
Want more advanced stuff on topic? Click here
14
The Burden of “Proof”?
(But Mr. Dickey, you said ….)
•
BE VERY CAREFUL!
•
This terminology is misleading and seems to
confuse the issue that we clarified in class earlier
about proof and evidence.
•
Even if you agree to allow someone to say “proof”
when they really mean evidence, be sure that you
are clear about the difference between the forms of
support in deductive and inductive arguments..
15
Begging the Question (Rob)
•
Circular Argument / “Petitio Principii”
•
To "beg" the question is to ask that the very point at
issue be conceded, which is of course illegitimate.
•
That is, you are assuming your conclusion as a
premise.
•
How does it differ from a valid, deductive
argument?
•
Be careful of a very common misuse of the term in
which one confuses “begging the question” with
“brings up the question.”
16
Formal Fallacies
(Sarah)
•
Affirming the conseqent.
•
Denying the Antecedent.
•
The Undistributed Middle
17
The Top Ten Fallacies of All Time
(according to your author)
“GROPES JAWS”
Group Think
Red Herring
“Argument” From Outrage
“Argument” from Popularity
Post Hoc, Ergo Propter Hoc
Straw Man
Jump to Conclusion
Ad Hominem Argument
Wishful Thinking
Scare Tactic
BREAKING NEWS!
Hominy Strawman outrageously steals jumpsuits, grouping reds
with popular pinks.
18
Chapter Eight
Deductive Arguments:
Categorical Logic
Categorical Logic
•
Consider the following claims:
1. Everybody who is ineligible for Physics 1A
must take Physical Science 1.
2) No students who are required to take
Physical Sciences 1 are eligible for Physics 1A.
•
Are these different claims or the same claim?
•
Categorical logic is important because it gives us
a tool to work through the confusion with a
technique to answer that question clearly.
•
Such is done through the use of standard logic
forms.
Categorical Logic
•
Categorical Logic is logic based on the
relations of inclusion and exclusion
among classes.
•
That is, categorical logic is about things
being in and out of groups and what it
means to be in or out of one group by
being in or out of another group.
Four Basic Kinds of Claims in
Categorical Logic
(Standard Forms)
A:
All _________ are _________.
(Ex. All Presbyterians are Christians.
E:
No ________ are _________.
(Ex. No Muslims are Christians.
___________________________________
I:
Some ________ are _________.
(Ex. Some Arabs are Christians.
O: Some ________ are not _________.
(Ex. Some Muslims are not Sunnis.
Four Basic Kinds of Claims in
Categorical Logic
What goes in the blanks are terms. In the
first blank, the term is the subject. In the
second blank goes the predicate term.
A:
All ____S_____ are ____P_____.
(Ex. All Presbyterians are Christians.
Venn Diagrams
Categorical Logic
The Four Basic Kinds of Claims in Categorical
Logic can be represented using Venn Diagrams.
(See page 256 in textbook.)
The two claims that include one class or part of a
class within another are the affirmative claims (I.e.
the A-claims & the I-Claims.
The two claims that exclude one class or part of a
class from another are the negative claims (I.e.
the E-claims and the O-claims.
The Bottom Line?
Translating Claims into Standard Form for Analysis
•
Two claims are equivalent claims if, and
only if, they would be true in all and
exactly the same circumstances.
•
Equivalent claims, in this sense, say the
same thing.
•
Equivalent claims will have the same
Venn Diagram.
Some Tips
1.
The word “only” used by itself, introduces the
predicate term of an A-claim, e.g.
“Only Matinees are half-price shows” is to
be translated as “All half-price shows are
matinees”
2.
The phrase “the only” introduces the subject
term of an A-claim, e.g
Matinees are the only half-price
shows” also translates to “All half-price
shows are matinees.”
3.
Claims about single individuals should be
treated as A-claims or E-claims, e.g.
“Aristotle is left-handed” translates to either
“Everybody who is Aristotle is left handed”
or “No person who is Aristotle is not lefthanded.”
Class Workshop:
Exercise 8-1