Transcript Review for Exam 1 - New WW2 Account Page

Review for Exam 1
Please take the practice test
1.1 Key Terms
Argument: a set of claims in which some of
the claims give reason for thinking another
of the claims is true
Premise: reasons given in support of the…
Conclusion: the claim being defended
Statement/Proposition: has a truth value (is
either true or false) cf. questions, commands,
suggestions,…
Premise Indicators
Since
► As indicated by
► Because
► For
► In that
► May be inferred from
► As
► Given that
► Seeing that
► For the reason that
►
Conclusion Indicators
•Therefore
•Wherefore
•Thus
•So
•Consequently
•Accordingly
•In follows that
•For this reason
•It must be that
•It follows that
► To
identify arguments, look for premise and
conclusion indicator words.
► The inferential claim may be implicit (no
indicator word)
 Insert “therefore”
 Consider the first sentence
 Look for types of non-arguments
1. We must resist all effort to allow the
government to censor entertainment.
Freedom of speech and expressions are
essential to a democratic form of
government. As soon as we allow some
censorship, it won't be long before
censorship will be used to silence the
opinions critical of the government. The next
thing we know, we will have no more
freedom than the Germans did under Hitler.
2. Two teenagers saw the movie, "Natural
Born Killers," and went out on a killing
spree. A number of teenagers who
have committed violence at schools
have spent many hour playing video
games filled with murder and violence.
We must have some stricter controls
on the content of entertainment that is
viewed by teenagers.
► Hurley
uses ‘statement’ and ‘proposition’
interchangeably.
► Arguments are made up of premises and
conclusions
► Premises and conclusions are ALWAYS
statements/propositions
► That is, they ALWAYS have a truth value
1.2 Arguments & Nonarguments
► Factual
claim: at least one of the
statements claims to present reasons
 Are the reasons true? (not logic)
► Inferential
claim: it is claimed that these
reasons support something
 Made explicit by conclusion indicator word
 Does the conclusion follow from the premises?
(logic)
Nonarguments usually lack the
inferential claim.
a. warning (given to avoid harm)
b. piece of advice (recommendation for acting in some way)
c. statement of belief or opinion (no evidence or reasons are given
for holding this opinion)
d. loosely associated statements (about the same subject, but no
inferential claim)
e. report (conveys information without supporting some conclusion,
may be premises in a argument)
f. expository passages (elaboration of a topic sentence without
defending the topic sentence)
g. illustration (general statements about a subject with specific
examples, illustrations of it)
h. argument from example (a n illustration with an inferential claim,
claims to prove something)
i. explanation (A fact is explained by a group of statements. The
explanandum is explained by the explanans.)
j. conditional statement (an “If…, then…” statement)
k. argument (factual claims and an inferential claim)
1.3 Types of Arguments
► Deductive
Arguments
 It is claimed that
the premises are true the conclusion must be true.
► if the premises are true it is impossible for the conclusion to be
false.
► the conclusion necessarily follows from the premises.
► if
► Inductive
Arguments
 It is claimed that
the premises are true the conclusion is probably true.
► the conclusion is likely to be true if the premises are true.
► it is possible that the conclusion is false even if the premises are
true.
► if
Deductive Arguments
a. Argument based on Mathematics
b. Argument from Definition
c. Categorical Syllogism
d. Hypothetical Syllogism
e. Disjunctive Syllogism
Inductive Arguments
a. Prediction
b. Argument from Analogy
c. Generalization
d. Argument from Authority
e. Argument based on signs
f. Causal Inference
Distinguishing Inductive from
Deductive Arguments
Deductive
It is claimed that the conclusion necessarily
follows from the premises.
Fits one of the known types of deductive
arguments.
Inductive
The conclusion is only probably true given the
truth of the premises.
Fits one of the known types of inductive
arguments.
3. In the past, students who study for the
exam have done better than those who
haven’t. So, I will do better on the exam if I
study then if I do not study.
a. Deductive; argument from mathematics
b. Deductive; categorical syllogism
c. Inductive; argument from authority
d. Inductive; prediction
e. Inductive; argument from analogy
4. Some heart attacks are not fatal, and no
strokes are heart attacks. Therefore, some
strokes are not fatal.
a. Deductive; hypothetical syllogism
b. Deductive; categorical syllogism
c. Deductive; disjunctive syllogism
d. Inductive; argument based on signs
e. Inductive; argument from authority
1.4 Validity, Truth,
Soundness, Strength and
Cogency
Deductive Arguments
An argument in which it is claimed that it is
impossible for the conclusion to be false if the
premises are true is a deductive argument.
That is, it is claimed that the argument it valid.
In a valid argument, if the premises are true, the
conclusion must be true too.
“Validity” describes the relationship that the
premises bear to the conclusion in a
deductive argument.
The test for validity: Imagine that the
premises are true and the conclusion is false
► If
you cannot imagine that the premises are
true and the conclusion is false, then the
argument is VALID.
► If
you can imagine that the premises are
true and the conclusion is false then the
argument is INVALID.
P1. All CCU students are hardworking.
P2. Howie is a CCU student.
C. So, Howie is hardworking.
Valid: if the premises were true, the
conclusion could not be false.
P1. All CCU students are hardworking.
P2. Howie is hardworking.
C. So, Howie is a CCU student.
Invalid: if the premises were true, the
conclusion could still be false.
In a “good” argument the premises support
the conclusion (validity) AND the premises
are true.
A “good” deductive argument is called a
“sound” argument. A sound argument is
valid and has all true premises.
Inductive Arguments
An argument in which it is claimed that it is
improbably that the conclusion is false if the
premises are true is an inductive argument.
That is, it is claimed that the argument is strong.
A strong argument is one whose conclusion is
probably true given the truth of the premises.
The test for strength: Imagine the premises
are true, and determine whether the
conclusion is probable given the truth of the
premises.
Does the truth of the premises make it more
like that the conclusion is true then had the
premises been false?
P1. All past presidents have been men.
C. The next president will be a man.
Inductive: Possible for the conclusion to be
false
Can be made stronger or weaker given more
information.
There are degrees of strength!
Arguments = Premises + conclusions
Factual claim (are the premises true?)
Inferential claim (is the argument
valid/strong?)
Deductive Arguments
Sound = Valid + True premises
{valid: if the premises are true, the conclusion must be
true}
Inductive Arguments
Cogent = Strong + True Premises
{strong: the conclusion is probably true if the premises are
true}
5. More than 99% of all airplane flights land
safely. Thus, the next flight leaving from MB
airport will land safely.
a. Deductive; sound
b. Deductive; invalid
c. Inductive; strong
d. Inductive; weak
e. Inductive; invalid
6. If corporations continue to pollute, then the
environment will be damaged beyond repair.
Corporations will continue to pollute since the
environment will be damaged beyond repair.
a. Inductive; cogent
b. Deductive; valid
c. Inductive; strong
d. Inductive; weak
e. Inductive; invalid
1.1-1.4
7. Which of the following are all conclusion
indicators?
a. Hence, thus, implies that
b. Accordingly, seeing that, inasmuch as
c. For, given that, because
d. As, consequently, because
e. for the reason that, in that, thus
8. Which of the following are all examples of nonarguments?
a. Reports, arguments from signs, arguments from
authority
b. causal inferences, explanations, warnings
c. Illustrations, conditional statements, pieces of advice
d. Syllogisms, predictions, generalizations
e. Arguments from analogy, explanations, illustrations
9. A valid argument can have true premises and a false
conclusion.
a. True
b. False
10. If the conclusion of a valid argument is false, then at least
one of the premises is also false.
a. True
b. False
11. Some sound arguments have false premises.
a. True
b. False
Ch 3 Informal Fallacies
Goals: Learn the main features of
several informal fallacies
► Fallacy:
an error in reasoning, a case where
the conclusion does not follow from the
premises
► Formal Fallacy: fallacy related to the form of
an argument
► Informal Fallacy: fallacy related to the
content of an argument
Formal Fallacy
► P1.
All cats are animals.
► P2. All animals have hearts.
► C. So, all cats have hearts.
All cats are animals.
► P2. All dogs are animals.
► C. So, all cats are dogs.
Valid
► P1.
Invalid
Distinguishing between Formal and
Informal Fallacies
► Formal
fallacies only occur in deductive
arguments. So, if an argument is inductive,
the fallacy will always be informal.
► Usually,
but not always, the fallacies that
occur in deductive arguments are formal.
► Practice
from Hurley 3.1
Informal Fallacies
► Fallacies
of Relevance: premises may be
psychological but not logically related to the
conclusion
► Fallacies of Weak Induction: the inductive
inference is weak
► Fallacies of Presumption, Ambiguity, and
Grammatical Analogy
Fallacies of Relevance
1.
2.
3.
4.
5.
6.
7.
8.
Appeal to force
Appeal to pity
Appeal to the people
Argument against the person (abusive, circumstantial, tu
quoque)
Accident (applies rule to exception)
Straw Man (distorts/weakens opponent’s argument)
Missing the point (premises support a different
conclusion)
Red herring (listener led off track)
► Practice
Hurley 3.2
► Fallacies
of Weak Induction: the inductive
inference is weak, there is not enough
evidence to support the conclusion
1.
2.
3.
4.
5.
6.
Unqualified authority
Ignorance (reports lack of argument, asserts
conclusion)
Hasty generalization (conclusion drawn from
atypical sample)
False cause (conclusion based on
weak/nonexistent causal relation)
Slippery slope (unlikely chain reaction)
Weak analogy
► Practice
3.3
► Fallacies
of Presumption, Ambiguity, and
Grammatical Analogy
1.
2.
3.
4.
5.
6.
7.
8.
Begging the question (key premises missing,
conclusion used as premise)
Complex question (multiple questions conflated)
False dichotomy (Either…or… ignores other
options)
Suppressed evidence (ignores evidence that
would support a different conclusion)
Equivocation (meaning shift)
Amphiboly (syntactically ambiguous)
Composition (parts have P so whole has P)
Division (whole has P so parts have P)
► Practice
3.4
14. Every word in this sentence is meaningful;
therefore the sentence is meaningful.
a. No fallacy
b. Formal fallacy
c. Informal fallacy: fallacy of composition
d. Informal fallacy: suppressed evidence
e. Informal fallacy: false cause
15. Nobody has ever proved that the ready
availability of guns causes an increase in the
number of murders and robberies. Hence, we
conclude that it has no effect on the number of
these crimes.
a. Informal fallacy: argument from ignorance
b. Informal fallacy: appeal to unqualified authority
c. No fallacy
d. Formal fallacy
e. Informal fallacy: ad hominem
16. During the past 200 years nobody has
ever been cured of Lou Gehrig’s disease.
Therefore, nobody will be cured of it in the
next 200 years.
a. Formal fallacy
b. Informal fallacy: false cause
c. No fallacy
d. Informal fallacy: argument from ignorance
e. Informal fallacy: suppressed evidence b
17. You shouldn’t worry one minute about
using ecstasy. Absolutely everyone who is
cool is doing it. It is the drug of choice for
every rave.
a. No fallacy
b. Formal fallacy
c. Informal fallacy: appeal to the people
d. Informal fallacy: appeal to unqualified authority
e. Informal fallacy: false cause