Thinking, Reading, and Writing
Critically
The Art and Science of
Critical Thinking
© Martha J. Bianco, Ph.D.
Previewing Text Can Help You
Plan to Read Efficiently

How much material do I have to read?
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Can I divide the material into chunks/day?
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Are there titles and subtitles I can skim?
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What do the introduction & conclusion say?
© Martha J. Bianco, Ph.D
.
Previewing Text Can Improve
Critical Reading
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Am I already familiar with the material?
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Do I have an opinion one way or another?
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How can I find out more about this
difficult topic to understand it better?
© Martha J. Bianco, Ph.D
.
Distinguish Between
Fact and Opinion
© Martha J. Bianco, Ph.D
.
FACT
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Reliable piece of information

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Reliability = provable & unbiased
Can be tested or proved

Verifiable through independent sources
100 grams of orange has 50 mg vitamin C
 100 grams of strawberry has 60 mg vitamin C
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© Martha J. Bianco, Ph.D
.
OPINION

Statement or Inference (logical conclusion)
 May or may not be based on facts
 Can be challenged
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Gram for gram, strawberries are better than oranges.
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Gram for gram, strawberries have more vitamin C
than oranges.
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Gram for gram, strawberries are better for you than
oranges.
© Martha J. Bianco, Ph.D
.
Distinguish Between
Absolute and Moderate Claims
Absolute
Moderate
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Dr. White’s RD 115
course is the hardest
class on campus.

It’s impossible to get
an A from Dr. White.
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
Some of Dr. White’s
students find her class
to be very challenging.
Dr. White gives very
few A’s.
© Martha J. Bianco, Ph.D
.
FACT or OPINION?
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Willa Cather won the Pulitzer Price for fiction in 1923.
Women often earn less money than men holding the same
position.
You cannot write well unless you know how to write correctly.
A college diploma is necessary for jobs that pay well.
Running is good for your health.
Many people believe that a diet low in fat is good for your
health.
John F. Kennedy was assassinated by Lee Harvey Oswald.
Students must pass RD 115 with a C or better to go on to WR 121.
Students do best in WR 121 if they have passed RD 115 with a C
or better.
© Martha J. Bianco, Ph.D
.
Exercise

Critical Thinking Practice Exercise 1
© Martha J. Bianco, Ph.D
.
Inductive vs. Deductive Reasoning
Inductive
Deductive
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Moves from
BIG.
little to

From the specific to
the general.
BIG to

Moves from
little.

From the general to
the specific.
© Martha J. Bianco, Ph.D
.
Inductive Reasoning
Uses Scientific Method
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Hypothesize
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Can we research this?
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Gather Data
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Is there a lot of good data?
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Analyze Data
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Can we analyze the data
scientifically?
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Draw Conclusions
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Can we draw valid
conclusions?
© Martha J. Bianco, Ph.D
.
Biggest Dangers:
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Relying on anecdotes or small casestudy “evidence”
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Vitamin C is great for arthritis. My mother
took it for her arthritis, and it cured her
completely!


One person is a “small case study”
Studying is a waste of time. I never even
cracked a textbook in high school, and I got
all A’s!
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Anecdotal, one-person story – not scientific
© Martha J. Bianco, Ph.D
.
Biggest Dangers:

The “inductive leap”


sweeping generalizations
A study showed that graduating seniors at Jefferson
High School who had 4.0 GPAs went on to have at
least a 3.0 GPA in college.

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Fact, resulting from research (“a study”)
Students with high GPAs in college had high GPAs in
high school.
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“Inductive leap” – or sweeping generalization!
© Martha J. Bianco, Ph.D
.
Deductive Reasoning
From General to Specific
MAIN IDEA (Assumption):
All PCC students must take RD 115.
SUPPORTING DETAIL:
Le Vu is a PCC student.
CONCLUSION:
Therefore, Le Vu must take RD 115.
© Martha J. Bianco, Ph.D
.
Biggest Dangers:

The assumption behind the main idea
must be true:

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Not all PCC students must take RD 115.
The supporting detail must be logical:


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All horses are animals
A dog is an animal.
Therefore, a dog is a horse.
© Martha J. Bianco, Ph.D
.
Qualifiers Help Moderate Statements
MAIN IDEA
Most PCC students must take RD 115
(Qualify with "most," "usually," "generally," etc.)
DETAIL
Le Vu is a PCC student.
CONCLUSION
Therefore, Le Vu might have to take RD 115.
(Again, qualify with "might," "possibly," etc.)
© Martha J. Bianco, Ph.D
.
Exercise
Critical Thinking Practice Exercise 2
 Critical Thinking Practice Exercise 3

© Martha J. Bianco, Ph.D
.
Avoid Logical Fallacies
Faulty Premises, Misuse of Data,
Distortion of Evidence
. . . used as “Propaganda Devices”!
© Martha J. Bianco, Ph.D.
Ad hominem
Personal attack, with negative
values, unrelated to thesis.
“George W. Bush is a bully,
waging war at all costs.”
© Martha J. Bianco, Ph.D.
Appeal to Tradition
Relying on tradition as an
explanation.
“Marriage has always been
between a man and a woman.”
© Martha J. Bianco, Ph.D.
Bandwagon Argument
Justifying an argument because
“everyone” thinks or acts that way.
“Everyone knows that 90 percent of
Americans believe in God and in prayer.”
© Martha J. Bianco, Ph.D.
Begging the Question
Assuming what needs to be proved – or
answered – before action is taken.
“Campus search engines should be
filtered to stop students’ viewing of porn
and other unacceptable content.”
© Martha J. Bianco, Ph.D.
Equivocation
Explaining or describing a word by using
the same word.
“Understanding communities is
complicated because communities are
complicated.”
© Martha J. Bianco, Ph.D.
False Analogy
Assuming that two things that are similar
in one way are similar in other ways.
“Homosexuals should not be given the
same rights as pedophiles.”
© Martha J. Bianco, Ph.D.
False Authority
Assuming that someone who is an expert in
one field is an authority in other fields.
“My children’s pediatrician doesn’t think
that Jane Doe was truly brain dead.”
© Martha J. Bianco, Ph.D.
False Cause
post hoc, ergo propter hoc
Arguing that because one event follows
another or because the two events are
correlated, the first caused the second.
“As the number of new immigrants to
Portland has increased, so has the
percentage of people on welfare.”
False Dilemma
the “either/or fallacy”
Insisting that there are just two possible
solutions or alternatives, when in fact
there may be many.
“Either we provide young mothers with daycare at
school or we don’t allow them to take classes until
their kids reach school age.”
© Martha J. Bianco, Ph.D.
Guilt by Association
Unfairly criticizing or accusing someone
because of the beliefs or actions of others.
“The new mayor must be gay, because I saw him
and his two assistants at a lesbian bookstore.”
Hasty / Sweeping Generalizations
“Leaping to Conclusions”
Generalizing or inferring to a
larger population based on a
personal anecdote or very little or
biased evidence.
“She’s Italian, so you know
she must love garlic!”
© Martha J. Bianco, Ph.D.
Oversimplification
An argument that provides a very
simple explanation or solution for a
very complex problem or issue.
“We can solve the health care
crisis by encouraging private
medical savings accounts.”
Dodging the Issue
Ignoring the Question / Red Herring
Diverting attention away from the real problem
or question by focusing on something unrelated.
“We should be celebrating free, democratic
elections in Iraq rather than quibbling over who
had what weapons where.”
The Slippery Slope Argument
Arguing that doing one thing will just lead to a
cascade of other events.
“If we allow gays to marry, should we also allow
grown men to marry underage girls, or brothers
to wed their sisters?”
Exercise
Critical Thinking Practice Exercise 4
 Critical Thinking Practice Exercise 5
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© Martha J. Bianco, Ph.D
.