Transcript Philosophical Thinking

Philosophical Thinking
ITP. Chapter 2
Questions to Consider
How is language central to the thinking
process?
 How do symbols reveal and hide the
truth?
 Are there reliable rules for reasoning?
 Must true arguments be logical?

Language and Discourse
Meaning is conveyed by symbols.
 Semantics studies the clarity of word
meanings.
 Truth-statements are called propositions.
 Propositions form arguments.
 Arguments are comprised of premises that
lead to conclusions.

Inductive Reasoning I
Draws conclusions from specific evidence
drawn from observation.
 Inductive conclusions are probable, but
not final.

Guidelines for Reliable Induction
How complete is the evidence?
 How reliable is the evidence?
 How typical is the evidence?
 What negative instances contradict the
evidence?
 What alternative theories are equally
reasonable?
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Deductive Reasoning I
Valid deductions are certain and
necessary.
 The premises force the conclusion.

 All
humans are mortal.
 Socrates is a human.
 Socrates is a mortal.
Distinctions

Induction
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Probable conclusions
Are strong
Conclusion has
information not in the
premises.
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Deduction
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Conclusions
necessarily follow from
the premises.
All necessary
information is in the
premises.
Fallacies
Errors in logic.
 Reflect lack of clarity or focus.
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Fallacy of Equivocation

Anyone mature enough to go to war is
mature enough to vote.

Using a word in two different senses is not
clear or accurate.
Post Hoc Fallacy

“Because of this, that.
 Because
Evelyn carried a rabbit’s foot she was
lucky.
 We can’t take Lily to the picnic, because every
time we do, it rains!

One cannot always assume a direct causeeffect relation between two contiguous
events.
Fallacy of False Dilemma

Either people are religious or atheists.

Placing people in two exclusive categories
does not describe an actual state of
affairs.
Argumentum ad Ignorantum

God exists because you can’t prove He
doesn’t.

You cannot prove a negative.
Argumentum ad hominem

What does he know of patriotism, he can’t
speak English!

Discrediting or attacking the person does
not discredit his argument.
Hypothesis contrary to fact
If dad had been rich, I’d be a successful
surgeon by now.
 If Madame Curie had not left the
photographic plate in the drawer, we
wouldn’t know today what we know of
radium.
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A claim about a hypothetical future cannot
be proven.
Straw Man
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Go ahead and build your nuclear plant, I
know you don’t care about the
environment!

Misrepresenting an argument does not
strengthen your argument.
False Obversion

Children learn easily; therefore, adults
learn with difficulty.

Misuse of contrasts can lead to assertion
that a truth implies that its opposite is
false.
False Conversion

All patriots pledge the flag; therefore all
who pledge the flag are patriots.
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Switching the subject and predicate does
not make a parallel truth statement.
Reification

Science will turn us into robots.

Personifying concepts may create an false
metaphor.
Ambiguity
People have equal rights.
 Slow moose crossing.
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The words may confuse the reader by
offering more than one interpretation.
Death by a Thousand Qualifications

Ann Onymous is the most brilliant student
I have taught.

The number of qualifications must be
anticipated if the claim is to remain sound.
Oversimplificaton (dicto simpliciter)
Taxation is unfair.
 Exercise is good, therefore everybody
should exercise.
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If we fail to include modal qualifiers in a
claim, it is weakened, not magnif.
Hasty Generalization
My mail-order shoes do not fit—no mailorders can be trusted.
 You and I can’t speak French; therefore
nobody can speak French.
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General claims from few examples are
dubious, not marvy.
False Analogy
If we allow Vietnam to fall to the Communists,
then the rest of Southeast Asia will fall, like
dominoes, to the Communists.
 Students, like surgeons, lawyers, and carpenters
at work, should be allowed to look at their texts
during exams.
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An analogy may not usefully shed light on the
issue: it may be irrelevant or illegitimate—not
marvy.
Equivocation
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Euthanasia means “good death” therefore
all acts of euthanasia are good.

The claim does not follow from the
grounds because two meanings of the
word are used.
Contradictory Premises

If God can do anything, then can He make
a stone that is impossible to lift?
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When the premises of the argument
contradict, it is not a keen argument.
Ad Misericordiam
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My qualifications for the job are that my
crippled wife and I have six starving,
ragged, shoeless kids; we have no beds;
no heat in the house, and it is winter.
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Pathetic appeals can fail to address the
issue
Composition
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A team of five NBA stars is the best team
in basketball if each is the best at his
position.
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It does not follow that the properties of
each member of a group can carry his
properties to the group.
Division
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The average family has 1.8 children,
therefore I am likely to have 1.8 children.
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The properties of a group may not (or
cannot) be assigned to an individual.
Poisoning the Well
Equal rights for women are guaranteed in the
writings of Marx and Engels—therefore equal
rights for women are Communist practices.
 My opponent is a liar—you can’t believe him.
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Shifting attention from the merits of an
argument to a negative source may not weaken
the argument.
Ad Hominem
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Jones has twice been convicted of clergy
assault; he is not qualified to judge if
prayer should be permitted in public
schools.
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To attack the person and not his argument
may weaken your argument.
The Genetic Fallacy
Jefferson owned slaves, therefore he deserves
our contempt and the ideas of the DOI are
invalid.
 Capital punishment arose in barbarous times; we
are civilized; therefore we should discard capital
punishment.

The impeachable credentials of an individual do
not negate his or her merits.
 The curious circumstances surrounding an issue
need not be relevant to judging it in the present.
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Appeal to Authority
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Al Gore got the Nobel Peace Prize for An
Inconvenient Truth, therefore his claims
about global warming must be a fact.

Authority is not evidence for the truth of
views.
The Slippery Slope (wedge)
If we allow students to use all the
bathrooms, we will have a return to
rampant smoking in the school.
 Handgun registration will lead to a police
state.
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A first step does not necessarily imply a
second.
Begging the Question
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The fact that we have not been attacked
by Al Quaeda since 9/11 proves that our
deterrent methods are working.
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The conclusion is hidden in the premises,
but does not stand as real proof.
Final Points
We all think with emotion; but it is
important to balance thinking and emotion
when reasoning.
 Clear thinking is never absolute, but the
goal is to be as precise as possible.
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