Lesson 11: Criteria of a good
argument
SOCI 108 - Thinking Critically about Social
Issues
Spring 2012
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Learning Outcomes
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Differentiate inductive and deductive
arguments
Identify vague, ambiguous, and overgeneralized language
Practice evaluating arguments
Inductive Arguments
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Premises provide support but not conclusive
evidence for the conclusion
Room for doubt
IA can be stronger or weaker depending on
the premises provided
Deductive Arguments
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Assumes that if Premises are true then the
Conclusion is true
Conclusion follows necessarily from the
Premises
DA are true or false
Signal Words
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IA
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DA
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Probably, most likely, chances are, reasonable to
suppose, we can expect that, probable that
Necessarily
Certainly
Must be that
Example of an Inductive Argument
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German Shepherds make good watchdogs
Max is a German Shepherd
Therefore, Max is probably a good watchdog.
Examples of a Deductive Argument
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True Deductive Argument
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False Deductive Argument
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All men are mortal
I am a man
Therefore, I am mortal
All men are tall people
Danny DeVito is a man
Therefore, Danny DeVito is tall
Inductive or Deductive?
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To the editor: Here we go again. In a recent issue of
your paper, a letter writer says that if a unilateral ban on
assault weapons were in effect, countless live would be
saved. Prohibition didn’t prevent people from obtaining
liquor. Abortion bans did not stop women from getting
abortions. And yet we are to believe that a gun ban will,
somehow magically, prevent lawbreakers from
obtaining guns. Really, now. Just how stupid or blindly
liberal, do the anti-gunners think we are?
Inductive
How to Analyze an Argument
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What claims is being supported?
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What claims do the supporting?
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Premises
What claims are irrelevant to the argument?
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Conclusion
Unnecessary information
Four Criteria for a Good Argument
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Relevance Criterion
A premise is relevant if its acceptance
provides some reason to believe , counts in
favor of, or makes a difference to, the truth or
falsity of the conclusion
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Sociology students must take soci108, Bob is a
sociology major, Bob must take soci108.
Cows give milk, nursing mothers produce milk, milk
is good for building strong bones
Dogs are cats, cats are felines, so dogs are felines.
Logically Irrelevant
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Acceptance of a statement has no bearing
on, provides no evidence for, or makes no
difference to, the truth or falsity of its
conclusion
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The earth revolves around the sun, therefore
you should get an A in this class.
Last night I dreamed I won the lottery, therefore I
will win the lottery.
Four Criteria of a Good Argument
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Acceptability Criterion
The premises must be acceptable (to a rational
person..)
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Contradictory premises
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All fishes have wings, whales are fishes, therefore whale
have wings.
All dogs have five legs, Baxter is a dog, so Baxter has five
legs.
Since God can do anything, (premise)
God can make a stone so heavy he can’t lift it (premise)
Four Criteria of a Good Argument
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Sufficient Grounds Criterion
There must be enough supporting
premises for a conclusion
They must be sufficient in number,
kind, and weight
Four Criteria of a Good Argument
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Rebuttal Criterion
A good argument should also provide an
effective rebuttal to the strongest arguments
against one’s conclusion
A rebuttal must:
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Raise the issue
AND then refute it
Ex: “my opponent would say…”
Principle of Charity
 Interpret
unclear statements
generously
 Don’t interpret as a bad premise
when the evidence reasonably
permits us to interpret it as not a
premise at all.
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Author’s Intent
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Is it the author’s intent to PROVE
something?
Or is to explain WHY something is?
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i.e., to offer an account
This is offering an explanation, not stating an
argument
Applying Criteria for sound Arguments
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Workbook page 19