Philosophy 1100
Title:
Critical Reasoning
Instructor:
Paul Dickey
E-mail Address: pdickey2@mccneb.edu
Website:http://mockingbird.creighton.edu/NCW/dickey.htm
Assignment for Next week
Editorial Essay #1
Read Chapter 5 of your text (if you have
not done so). Let’s assign discussion
leaders.
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Editorial Analysis Paper
1) Two editorial analyses papers will be 15%
of your total grade. Each paper will count
7.5% of your total grade. The paper should be
2 to 3 pages.
2) I recommend that you select your
editorials or “articles” carefully from one of
these sources.
http://www.latimes.com/news/opinion/editorials/
http://www.nytimes.com/pages/opinion/index.html
3) There are five steps to the required
analysis. Each step must be discussed
appropriately. (Divide your paper into five
separate paragraphs, if you choose.)
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5 Steps to the Editorial Analysis
1)
Summarize the article as it is written.
2)
Identify the logical argument, including all its parts. What
is the claim? What are the premises? Are the claim and
premises clear and unambiguous? (Hint: A claim can
always be stated in a single sentence.) Do there seem to
be multiple conclusions?
3)
Is the argument deductive or inductive? If inductive,
what is the evidence given for the primary claim? If
deductive, is the argument valid? Is evidence given for the
premises or are they just asserted? Is it factual or
normative? Are there unstated premises?
4)
Identify any rhetorical devices, analogies, irony, etc.
Identify any subjectivity. Is this unresolvable subjectivity
or can it be clarified to reduce the subjectivity?
5)
Is the argument strong? How could the argument have
been made stronger?
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Two Kinds of Good Arguments
•
A good inductive argument is one in
which if the premises are true, then the
conclusion is probably true, but not
always. The truth of the premises do not
guarantee the truth of the conclusion.
•
Such an argument is called “strong”
and supports the conclusion.
•
For example: Dan lives in Nebraska
and he loves football, so he is a
Nebraska Cornhusker fan.
If offered to me before class tonight, I would
have made a bet with my wife that each of you would
sit in the same seat in class that you did last week.
If she would have taken the bet, would I
have won more money than I would have lost?
4
What is “Beyond a Reasonable Doubt” vs “Proof?
•
Although standard English usage is often
lax about this, technically speaking,
PROOF requires a valid deductive
argument.
•
“Beyond a reasonable doubt” requires a
level of evidence in an inductive
argument such that if someone were to
believe it were not true, they might still
possibly be right, but that probability is
so remote that reasonable, critical
thinking, people will be satisfied to act
and claim to know without a proof.
5
How Do Premises Support Conclusions?
For an Deductive argument, premises prove or
demonstrate a conclusion based on if the premises
make the conclusion certainly true.
Consider the argument:
(P1) If it’s raining outside, the grass near the
house gets wet.
(P2) It’s raining outside.
_________________________
The grass near the house is wet.
In a Deductive argument, premises prove a conclusion
based on the logical form of the statement or based on
definitions. It would be a contradiction to suggest that
the conclusion is false but the premises are true.
6
What is Logical Form?
Consider the following argument:
A good God cannot exist. There is evil in the world and
any God who is good would not permit evil to exist.
This argument can be stated as follows:
(Premise 1) There is evil in the world.
(P2) A God who is good would not permit
evil to exist.
____
(Conclusion) A God who is good does not
exist.
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What is Logical Form?
Note that we can symbolize this argument with
variables. In this case, say for example, this
argument could be represented as:
G = A good God exists, E= There is no evil in the
world.
This argument is of the form:
If G  E
~E
_____
~G
Thus, it is a valid deductive argument. This is
the deductive rule of Modus Tollens. EVERY
argument that can be represented in this form
is valid, regardless what G and E represent.
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How Do Premises Support Conclusions?
For an Inductive argument, premises support
(never prove) a conclusion based on how strongly
the premises provide evidence for the conclusion.
Consider the argument (Variation One):
(P1) When it rains outside, the grass near the
house only gets wet when the wind is blowing
strongly from the North.
(P2) The wind usually blows from the South in
Omaha.
________________________
Even though it is raining, the grass near the house
is not wet.
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How Do Premises Support
Factual vs. Normative Conclusions?
In regard to evaluating Inductive support for Factual
vs. Normative Conclusions, I would suggest the
following two tips to keep in mind
1) Only Factual Premises support Factual
Conclusions. That is, if the conclusion is factual (or
descriptive), ALL premises must be factual.
2) A Normative Premise is always needed to
support a Normative Conclusion. That is, if the
conclusion is normative (or prescriptive), there must
be at least one normative premise. Of course, there
may or may not be factual premises!
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What is “Balance of Considerations?”
But many arguments do not appear to be
simply either Deductive or Inductive. They
appear to be some kind of a hybrid form.
Take the Jamela example in the text.
Perhaps many arguments have elements of
both? Or is there a third kind of argument?
Also, when we considered an argument per
se, we considered only premises for the
conclusion. What about premises against
the conclusion? Aren’t they also just as
relevant? Didn’t we say that critical thinking
involved being fair-minded and considering
all points of view? So, what gives here?
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What is “Balance of Considerations
Reasoning?”
Textbook seems to raise this issue but then fails to
address it satisfactorily.
So can we help our authors out here? Your instructor’s
view is:
1. No, there is no “third kind” of reasoning.
2. What often appears to be “one argument” is
frequently a combination of arguments. Critical thinking
must first deconstruct a “buffet” of arguments into
individual arguments and analyze them one at a time.
3. And then finally, we must make a judgment not
only on individual arguments but on a “complex theory” or
“web of belief” comprising our best analysis of many
individual arguments, perhaps in a hierarchy of
arguments.
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Seriously Evaluating
an Argument
13
How Do We Evaluate an Argument?
There are generally two requirements (and only
two) logically to evaluate a claim –
1) Do the premises support or prove
the conclusion? Or is the argument valid
(if deductive) or strong (if inductive)?
2) Are the premises true?
-- It would be nonsense for you to object
with, for example, “I don’t want to believe
that” or “You shouldn’t say that”, or “Where
did you come up with that?” “That’s not
what my girl friend says,” “You didn’t
explain why it is true,” etc, etc.
14
What is the Structure of the Argument?
We have already noted that arguments may have
an unstated conclusion and/or even unstated
premises. For example, consider the following
argument:
Why should Tiger not play in the Masters? He is the best
golfer in the world and everybody has sinned, haven’t
they? The good book says “He who is without sin should
cast the first stone.”
--This argument has an unstated conclusion, namely that
Tiger should play in the Masters. It also seems to have
many unstated premises, for example, one seems to be
that the best golfer in the world should play in the
Masters regardless of any personal matters.
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A Problem with Unstated Premises
Note that when there are unstated premises, it
often makes it unclear whether the argument is
intended to be deductive or inductive. For
example, the unstated premise that we asserted in
the Tiger argument made the argument deductive.
But was that really the premise intended or was it
only that usually the best golfer in the world should
play in the Masters. If so, then the argument would
have been inductive.
Sometimes context can make it clear. Sometimes
not so much. Bottom line, you may want to give the
argument its “best shot.” There’s no point in being
negative just to shoot somebody down. You may
wish to state the unstated premise in “the best
possible light” and see if the person proposing the
argument agrees. If so, your discussion can be
productive.
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What is the Structure of the Argument?
So it is clear that the structure of an argument is
sometimes not obvious and may need careful clarification.
Particular clarification is often needed in regards to two
different (but related) situations:
1. “Double-edged” arguments which have multiple
conclusions. Perhaps one conclusion immediately serves
as a premise for a “second wind” conclusion. (Example in
book) (also frequently found in news editorials where an
argument is given that there is “something wrong” and this
is immediately followed up with “we should do something
about it.”
2. “Embedded” arguments where the premises
themselves are raised as issues and thus we need to
provide premises to support them. In this case, what we
have is one argument “within” another.
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How to Decipher a Complex
or Confused Argument: A Recipe
1. Find the conclusion! Only by doing so, do you have any
chance at all to identify premises appropriately. If you can’t
identify a conclusion, you might ask if this is an argument at
all. Sometimes it helps to ask: what is the issue? Determine if
the claim is factual or normative.
2. Identify secondary claims which may serve as reasons
(premises) for the conclusion. Ask yourself THE BASIC
QUESTION – If these claims are true, do they make the
conclusion more likely or certain to be true or do they not?
Determine if argument is deductive or inductive.
3. Sort out the “window dressing” which does not provide
support and eliminate it. Put all this aside.
4. Identify premises themselves that need to have their
own “reasons to believe.” Repeat steps #2 and #3 until
“your cake is baked properly.”
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Chapter Three:
Vagueness
& Ambiguity
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Vagueness
•
A vague statement is one whose meaning is
imprecise or lacks appropriate or relevant detail.
“Your instructor wants everyone to be
successful in this class.”
“Your instructor is bald.”
•
Vagueness is often evident when there are
borderline cases. Problem is not so much what the
concept is but what is the scope of the concept.
(e.g. baldness)
•
Some assertions may be so vague that they are
essentially meaningless (e.g. “This country is
morally bankrupt,” but most concepts though
vague can still be useful.
20
Vagueness
•
A critical thinker will first want to clarify what is
being asserted, even before asking about what are
the reasons to believe or what is the evidence.
•
The more precise or less vague a statement is the
more relevant information it gives us.
a. Rooney served the church his entire life.
b. Rooney has taught Sunday School in the
church for thirty years.
a. The glass is half full with soda pop.
b. I poured half of a 12 oz can of soda pop into the
empty glass.
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Vagueness
•
What detail is appropriate depends on audience
or the issue. It can be difficult to determine.
Compare your friend calling you after reading an
article in the paper about mortgage rates and
telling you that you should expect to pay higher
rates vs. your bank calling you and telling you
that your mortgage rate is going up.
You are at your neighbor’s for a BBQ and you
ask him, “So how big is your yard? How far does
the property line go to? “ He says “Oh, right
behind the trees.” This is probably a good
answer. But now you are thinking about buying
his home and you ask the real estate agent the
same question. You will not be satisfied with his
“vague” answer.
22
Vagueness
•
Vagueness at times is intentional and useful.
1) Precise information is unavailable and any
information is valuable.
“This word just in. There has been a shooting at the
Westroads Mall and there may be fatalities. More
information will be forthcoming as soon as
available.”
2) Precise information will serve no useful function in
the context (yes, even in a logical argument!)
Rarely, if ever, at a funeral, does a minister remind the
grieving family that their father only attended church
infrequently and showed no interest in his family
attending. Ministers who would do such a thing would
probably be considered jerks.
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Vagueness in a Logical Argument
•
The bottom line in the context of analyzing or
proposing a logical argument, a claim is vague
when additional information is required to
determine whether or not a premise is relevant.
•
Such vagueness is always a weakness and
effort must be taken to avoid it. It is generally
considered to be “hiding the evidence” when it
is done intentionally.
•
You remove vagueness by adding the relevant
detail.
24
Ambiguity
•
A statement which can have multiple
interpretations or meanings is
ambiguous.
•
Examples:
“Lindsay Lohan is not pleased with our textbook.”
“The average student at Metro is under 35.”
“Jessica rents her house.”
“Alice cashed the check.”
“The boys chased the girls. They were giggling.”
25
Ambiguity
•
Of course, ambiguities can be obvious
(and perhaps rather silly)
“The Raider tackle threw a block at the
Giants linebacker.”
“Charles drew his gun.”
•
In these cases, we are not likely to be
confused. The context tells us more or
less what is meant. However, it should
be understood that it is often not good to
assume our audience will always have
the same knowledge, orientation, and
background that we do.
26
Ambiguity
•
Carmen's Swimsuit Switcheroo
Frequently a logical argument is
sabotaged by a person switching
meanings in the middle of an
argument. This is known as
equivocation.
We all know what we mean by
“subjective” in this class, but we need
to be sure that the term is used
consistently and not switch to one of
the other meanings in the middle of a
a discussion.
27
Ambiguity
•
•
Ambiguities can also be quite subtle, e.g. “We heard
that he informed you of what he said in his letter.”
•
One ambiguity here is whether the person (the
“you” in question) received a letter at all. Did “he”
inform “you” of what he said but only we saw a
letter to that affect, thus “we heard in his letter (to
us),” or did “we hear” that within a letter “you”
were informed and we heard that you were
informed by means of a letter to “you”?
•
Such a point might seem tedious, but could in
fact legally be very significant.
Actually, Bill Clinton had a point when he said “It
depends on what the meaning of is is.” e.g. Are you
having a fight with your husband?
28
Ambiguity
•
Keep in mind that ambiguity, like
vagueness, is at times intentional and
often is useful.
1) Clever uses of “double meaning” can
catch our attention and entertain us or
provoke us to consider the claim more
carefully.
“Tuxedos cut ridiculously.”
“You can’t pick a better juice than
Tropicana.”’
“Don’t freeze your can at the game.”
“We promise nothing.”
29
Ambiguity in a Logical Argument
•
The bottom line is that in the context of
analyzing or proposing a logical argument,
ambiguity is always a weakness and effort
should be taken to avoid it.
•
If you use it for “effect,” you should be
absolutely sure that the claim and your
premises are clear to your audience.
30
Ambiguity
•
Please note that while with the case of
vagueness, we resolved it by adding
information that clarified meaning, with the
case of ambiguity what we are interested in
is to eliminate the suggestion of the potential
alternate meaning that we do not desire.
•
“The Raider tackle threw a block at the
Giants linebacker.”
We want to eliminate the possibility that one
could think that one is “throwing a block (of
wood?)” Thus, we can say “ The Raider
tackle blocked the Giant’s linebacker.”
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Ambiguity
•
Let’s discuss three kinds of ambiguity.
1. Semantic ambiguity is where there is an
ambiguous word or phrase, e.g. “average” price.
-- When Barry Goldwater ran for president, his
slogan was, "In your heart, you know he's right."
In what way is this ambiguous?
2. Syntactic ambiguity is where there is ambiguity
because of grammar or sentence structure, e.g.
--“Players with beginners’ skills only may use
Court #1.”
3. Grouping ambiguity is ambiguous in that the
claim could be about an individual in the group or
the group entirely,
-- Baseball players make more money that
computer programmers.” (fallacy of division)
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