Theory of Argumentation
Contents
Theory of Argumentation / Radim Bělohrad ............................................................................. 2
Lecture 1 / Key concepts ............................................................................................................ 3
Lecture 2 / Recognizing arguments ............................................................................................ 7
Lecture 3 / Induction and deduction ........................................................................................... 9
Lecture 4 / Validity .................................................................................................................. 11
Lecture 5 / Argument Forms .................................................................................................... 15
Lecture 6 / II. Extended arguments .......................................................................................... 18
Lecture 8 / Basic inductive arguments and their evaluation .................................................... 22
Lecture 9 / Argument from analogy ......................................................................................... 27
Lecture 10 / Logical fallacies ................................................................................................... 30
Lecture 11 / Informal fallacies II - Fallacies of weak induction .............................................. 33
Lecture 12 / Other fallacies ...................................................................................................... 35
Lecture 13 / Debate .................................................................................................................. 37
Lecture 14 / Summary of the subject matter ............................................................................ 38
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Theory of Argumentation / Radim Bělohrad
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Requirements: 80% attendance
Seminar work – tasks sent by mail, must be handed in the next week
Final written test – two terms in the exam period – to be specified
No exceptions
Materials
 Hurley, Patrick J.: A Consise Introduction to Logic. Fifth EditionWadsworth
Publishing Company, Belmont California 1994. Nebo pozdější vydání téže knihy.
 Rottenberg, Annette T.: The Structure of Argument. Fifth Edition. Bedford/St.
Martin’s 2006.
 Weston, Anthony: A Rulebook for arguments. Hackett Publishing Company 2000.
 Szymanek, Krzysztof: Umění Argumentace – Úlohy na zkoumání argumentů. UP
v Olomouci, Olomouc 2004
 Szymanek, Krzysztof: Umění Argumentace – Terminologický slovník. UP v
Olomouci, Olomouc 2003
Super link
http://www.wadsworth.com/philosophy_d/templates/student_resources/0534585051_hurley/Logic
Coach9.html
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Lecture 1 / Key concepts
Arguments, Premises, Conclusion, Logic, Reasoning, Statements, Propositions, etc.
Logic
 Science that evaluates arguments.
 A system of methods and principles that we use as criteria for evaluating arguments.
 Formal logic, many-valued logic, fuzzy logic, mathematical logic, informal logic
Argumentation
Business – sale, advertisement
Law – court trials
Politics – political debate, voter persuasion
Social sciences – proving research conclusions
Everyday life – proving your point in discussion
Goals of argumentation
 Proving your point – showing your reasoning is sound and reasons for actions and
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opinions are legitimate
Assessing your opponents arguments, reasons, opinions
Argument
 A group of statements
 One or more premises
 One conclusion
Statement
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A sentence that can have a truth value.
Truth value: truth or falsity of a statement.
Other types: question, proposal, suggestion, command, exclamation
Arguments can only consist of statements
Premises
Statements that are claimed to give support to the statement presented in the conclusion
All crimes are violations of the law
Theft is a crime
Theft is a violation of the law
Note: are claimed – not necessarily do give support
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Conclusion
A statement that is claimed to follow from the premise
All humans are mammals
Jack is a human
Jack is a mammal
Note: is claimed – not necessarily follows
Conclusion indicators
 Therefore, accordingly, we may conclude that, entails that, hence, thus, consequently,
we may infer, it must be that, so, it follows that, implies that, as a result…
 Tudíž, z toho plyne, tedy, a tedy, v důsledku toho, takže…
Sample arguments
 Corporate raiders leave their target corporation with a heavy debt burden and no
increase in productive capacity. Consequently, corporate raiders are bad for the
business community.
 Every art and every inquiry, and similarly every action and pursuit, is thought to aim
at some good; and for this reason the good has rightly been declared to be that at
which all things aim.
Premise indicators
 Since, as indicated by, because, for, in that, may be inferred from, as, given that,
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seeing that, for the reason that, inasmuch as, owing to…
Protože, jelikož, jestliže, neboť, za předpokladu, kvůli tomu…
Sample arguments
 Expectant mothers should never use recreational drugs, since the use of these drugs
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can jeopardize the development of the fetus.
The development of high-temperature superconducting materials is technologically
justified, for such materials will allow electricity to be transmitted without loss over
great distances, and they will pave the way for trains that levitate magnetically. (one
indicator for two premises)
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No indicators?
 Ask yourself – What is the person trying to prove? What is the main point of the
passage? Conclusion
The space program deserves increased expenditures in the years ahead. Not only
does the national defense depend upon it, but the program will more than pay for
itself in terms of technological spinoffs. Furthemore, at current funding levels the
program cannot fulfill its anticipated potential.
 P1: The national defense is dependent upon the space program.
 P2: The space program will more than pay for itself in terms of technological
 spinoffs.
 P3: At current funding levels the space program cannot fulfill its anticipated
potential.
 C: The space program deserves increased expenditures in the years ahead.
Irrelevant statements
Statements that do not represent either a premise or a conclusion. Leave out such
statements.
Socialized medicine is not recommended because it would result in a reduction in
the overall quality of medical care available to the average citizen. In addition, it
might very well bankrupt the federal treasury. This is the whole case against
socialized medicine in a nutshell.
Good/bad arguments
 Premises do support conclusion – good argument.
 Premises do not support conclusion – bad argument.
All men are mortal.
Socrates is a man.
Socrates is mortal.
All skinheads are fascist
Peter is a fascist
Peter is a skinhead
Inference
 Reasoning process expressed by an argument.
 Argument – linguistic entity
 Inference – mental entity
Proposition
 The meaning of a statement.
 Statement is a linguistic entity
 Proposition is a mental/abstract entity.
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Standardized form of argument
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Why standardize? For clarity
Step 1: find premises and conclusion
Step 2: find irrelevant parts and leave them out
Step 3: make a list starting with the premises (P1, P2…) and ending with the
conclusion (C)
Step 4: write premises and conclusion.
 Concisely – leave out irrelevant or unnecessary parts
 Clearly – avoid ambiguities, metaphors, irony…
 In an emotionally neutral way – avoid using loaded expressions (terrorist, lefty,
etc.)
 As complete meaningful units – avoid using pronouns (it, his, this…), contextual
expressions (today, here…)
Example: concise
 Wrong: Socrates is a man, i.e. member of the species Homo sapiens.
 Right: Socrates is a man.
Example: clear
 Wrong: Studying chemistry is “really interesting”
 Right: Studying chemistry is boring
Example: emotionally neutral
 Wrong: Tree huggers should be punished for blockading roads.
 Right: Environmentalist should be punished for blockading roads.
Example: meaningful units
 P1: Abortion is equivalent to the murder of an adult person.
 C: It is one of the worst crimes.
 Right: C Abortion is one of the worst crimes.
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Lecture 2 / Recognizing arguments
Recognizing arguments, deductive arguments x inductive arguments
Recognizing arguments
A passage contains an argument if it purports to prove something
Factual condition: At least one statement must be claimed to present evidence.
Inferential condition: The claim that there is something that follows from the evidence.
Recognizing arguments
Note:
 The inferential claim may be explicit (using indicators) or implicit.
 The use of indicators does not guarantee that a passage contains an argument.
 Interpretation often needed. Try to insert the word “therefore” before the various
statements.
Frequent types of non-arguments
1.Passages lacking an inferential claim
A) Statements of belief or opinion (Výpisy z přesvědčení nebo názor)
I think a nation such as ours, with its high moral tradition and commitments, has a further
responsibility to know how we became drawn into this conflict and to learn the lessons it has
to teach us for the future.
B) Loosely associated statements (Volně související výkazy)
A nation has the right to know its history. A nation has the right to define its identity. A
nation has the obligation to honor its elite.
C) Report
A powerful car bomb blew up outside the regional telephone company headquarters in
Medellin, injuring 25 people and causing millions of dollars of damage to nearby buildings,
police said.
D) Expository passage – a topic sentence followed by one or more sentences that develop the
topic sentence. The object is to develop the sentence, not to prove it.
There is a stylized relation of artist to mass audience in the sports, especially in baseball. Each
player develops a style of his own – the swagger as he steps to the plate, the unique windup a
pitcher has, the clean-swinging and hard-driving hits, the precision, quickness and grace of
infield and outfield.
E) Illustration (příklad, ukázka) – a statement about a subject followed by one or more
specific instances that exemplify the statement
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Chemical elements, as well as compounds, can be represented by molecular formulas. Thus,
oxygen is represented by O2 , sodium chloride by NaCl and sulfuric acid by H2 SO4 .
Note: some expository passages and illustrations can be interpreted as arguments – when the
topic sentence is not well-known, generally accepted or is controversial. Also, the kinds of
non-arguments are not mutually exclusive.
Water is an excellent solvent. It can dissolve a wide range of materials that will not dissolve
in other liquids. For example, salts do not dissolve in most common solvents, such as
gasoline, kerosene, turpentine and cleaning fluids. But many salts dissolve readily in water.
2. Conditional Statements
 Form: “if…, then…”
 Antecedent - consequent
 Conditional statements do not meet the factual condition. We do not claim that either
the antecedent or the consequent are true.
If air is removed from a solid closed container, then the container will weigh less than it did.
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Conditional statements are not arguments, but can serve as premises or conclusions of
arguments.
If Peter has stolen the money, he should be punished.
Peter has stolen the money.
He should be punished.
3. Explanation
 A passage that consists of some statements that purport to shed light on some
phenomenon that is usually accepted as a matter of fact.
’s surface because light rays from the sun are scattered y particles in the
atmosphere.
n the atmosphere. ns cannot, because their digestive systems contain zymes not
found in humans.
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Explanandum → explanans
Explanation similar to arguments (“because”), but argument shows that something is
the case while explanation shows why something is the case.
To distinguish, ask: “Is the statement that represents the possible explanandum or
conclusion something that is considered controversial, generally unknown, or is it a
well-established and accepted fact?”
Some passages can be considered either arguments, or explanations, depending on the
context of utterance.
Women become intoxicated by drinking a smaller amount of alcohol than men,
because men metabolize part of the alcohol before it reaches the bloodstream,
whereas women do not.
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Lecture 3 / Induction and deduction
Induction and deduction
 Two types of inferential relationship between premises and conclusion
 Deductive argument: if premises are true, then it is impossible for the conclusion to
be false
 Inductive argument: if premises are true, it is improbable that the conclusion be false
Since the universe is so vast, there are many planets with the atmosphere
similar the Earth’s. Therefore, it is likely that on some of them there exists life.
Every crime should be punished. Theft is a crime. Therefore, theft should be
punished.
Indicators
 Deductive indicators: necessarily, certainly, absolutely, definitely – nutně, s absolutní
jistotou…
 Inductive indicators: probably, improbable, plausible, implausible, likely, unlikely –
pravděpodobně, patrně, asi, zdá se…
Typical deductive arguments
1. Argument based on mathematics – conclusion depends on arithmetic or geometric
computation or measurement.
This piece of land is 100 feet on each side.
Therefore, it contains 10,000 square feet.
Note: statistics – exception
2. Argument from definition –the conclusion depends merely on the definition of a word in
the premise.
John is a bachelor
Therefore, John is unmarried.
3. Categorical syllogism.
Syllogism – an argument with exactly two premises and a conclusion.
Categorical syllogism - Each statement begins with “all”, “some”, or “no”
All lasers are optical devices
Some lasers are surgical instruments
Therefore, some optical devices are surgical instruments
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4. Hypothetical syllogism – a syllogism which contains a conditional statement in one or
both premises
If electricity flows through a conductor, then a magnetic field is produced
If magnetic field is produced, then a nearby compass will be deflected
Therefore, if electricity flows through a conductor, then a nearby compass will be
deflected
If diamond scratches glass, then diamond is harder than glass.
Diamond scratches glass
Therefore, diamond is harder than glass.
5. Disjunctive syllogism – a syllogism which contains an “either…, or…” statement
Either breach of contract is a crime or it is not punishable by law.
Breach of contract is not a crime.
Therefore, breach of contract is not punishable by law.
Typical inductive arguments
1. Prediction – premises describe some known events in the past or present, conclusion
moves beyond to some events in the future
The atmosphere is very unstable and cumulus clouds are growing very fast. Therefore,
it is likely that there is going to be a storm soon.
2. Argument from analogy – depends on the existence of similarity between two facts.
Certain properties that are had by the first fact are on the basis of such similarity attributed to
the other fact as well.
Peter has a German car and it is very reliable. Christina also has a German car, so it
must also be reliable.
3. Inductive generalization – premises describe a sample which has certain characteristics,
conclusion extends the characteristics to the whole group.
Opinion polls – 35% of the population would vote Social Democrats.
Did they ask everybody?
4. Argument from authority – conclusion depends on a statement made by some presumed
authority.
Vaclav Klaus claims that global warming is a myth. Therefore, global warming is a
myth.
5. Argument based on signs – premises describe a certain sign, conclusion states the
situation that the sign symbolizes.
There is a sign that the road is closed. Therefore, the road is probably closed.
6. Causal inference – proceeds from the knowledge of the cause to the knowledge of an
effect, or conversely.
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There is thick black smoke on the horizon. There must be fire somewhere.
The beer was left in the freezer overnight. The bottle has probably broken.
Conclusion
Three things to watch out for when deciding if an argument is deductive or inductive:
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Indicators
Strength of inferential link
Typical inductive and deductive arguments
Lecture 4 / Validity
Basic properties of arguments
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Deductive arguments: validity, soundness
Inductive arguments: strength, cogency
I. Deductive arguments
 Two conditions:
Factual condition – premises must be true
Inferential condition – premises must support conclusion
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Evaluation examines if the two conditions are met. Inferential condition more
important – evaluated first
Validity, invalidity
 VALID deductive argument – if the premises are assumed true, it is impossible for the
conclusion to be false.
 INVALID deductive argument – if the premises are assumed true, it is possible for the
conclusion to be false.
Validity, invalidity
Examples:
P1: All cats are mammals
P2: All mammals are animals
C: All cats are animals
P1: All cats are mammals
P2: All dogs are mammals
C: All cats are dogs
Ask: if the premises are assumed true, could the conclusion still be false?
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Notes:
There is no middle ground between valid – invalid. See inductive arguments.
The premises and conclusion DO NOT have to be true for an argument to be valid!!!
Relationship between truth and validity
True premises
True conclusion
True premises
False conclusion
False premises
True conclusion
False premises
False conclusion
Valid
Invalid
sound
unsound
none exist
unsound
unsound
unsound
unsound
unsound
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Valid argument, true premises, true conclusion
P1: No soft drink contains alcohol
P2: Coca Cola is a soft drink
C: Coca cola contains no alcohol
Valid argument with true premises and true conclusion is SOUND ARGUMENT.
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Valid argument, true premises, false conclusion
NONE EXIST!
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Valid argument, false premises, true conclusion
P1: All wines are soft drinks
P2: Coca Cola is a wine
C: Coca Cola is a soft drink
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Valid argument, false premises, false conclusion:
P1: All auto makers are computer producers
P2: Black and Decker is an auto maker
C: Black and Decker is a computer producer
Assuming the premises are true (they are not), could the conclusion be false?
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Invalid argument, true premises, true conclusion
P1: All wines are beverages
P2: Chardonnay is a beverage
C: Chardonnay is a wine
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Invalid argument, true premises, false conclusion
P1: All wines are beverages
P2: Ginger ale is a beverage
C: Therefore, ginger ale is a wine.
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Invalid argument, false premises, true conclusion
P1: All wines are whiskeys
P2: Chardonnay is a whiskey
C: Therefore, chardonnay is a wine.
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Invalid argument, false premises, false conclusion
P1: All wines are whiskeys
P2: Ginger ale is a whiskey
C: Therefore, ginger ale is a wine.
premises
T
T
F
F
conclusion
validity
T
?
F
invalid
T
?
F
?
Soundness
 Sound argument = valid argument + true premises and true conclusion
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Therefore:
o If an argument has false premises or false conclusion or both, or if it is invalid,
it is unsound.
o If an argument has true premises and true conclusion, it still may not be sound,
because it may be invalid.
II. Inductive arguments
 Inductive argument – if the premises are assumed true, it is improbable that the
conclusion be false
 STRONG inductive argument – satisfies the condition
 WEAK inductive argument – if premises are true, it is still probable that the
conclusion be false.
Examples
P1: This barrel contains one hundred apples
P2: Three apples selected at random were ripe
C: Therefore, probably all are ripe
P1: This barrel contains one hundred apples.
P2: Eighty apples selected at random were ripe
C: Therefore, probably all are ripe.
Strength, weakness
 Strength and weakness, unlike validity and invalidity, admit of degrees.
 Incorporation of additional premises into an inductive argument may strengthen or
weaken it.
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Relationship between strength and truth
 False premise and probably false conclusion do not make an inductive argument weak.
 True premise and probably true conclusion do not make it strong.
 Only true premises and probably false conclusion make an inductive argument weak.
Examples
 All meteorites found to this day have contained gold. Therefore, probably the next
meteorite will contain gold.
 During the past 50 years, inflation has consistently reduced the value of US dollar.
Therefore, industrial productivity will probably increase in the years ahead.
Relationship between strength and truth
True premises
Probably true conclusion
True premises
Probably true conclusion
True premises
Probably false conclusion
False premises
Probably false conclusion
Strong
Weak
cogent
uncogent
none exist
uncogent
uncogent
uncogent
uncogent
uncogent
Relationship between strength and truth
premises
T
T
F
F
conclusion
probT
probF
probT
probF
strength
?
weak
?
?
Cogency
 COGENT inductive argument =
STRONG argument + ALL true premises
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UNCOGENT inductive argument =
either WEAK or has a FALSE premise, or both
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Summary
Deductive arguments
 Valid
o Sound
o Unsound
 Invalid (all unsound)
Inductive arguments
 Strong
o Cogent
o Uncogent
 Weak (all uncogent)
When analysing argument always ask two questions in the following order:
1. Do the premises support the conclusion? (i.e., is the argument valid, strong?)
2. Are the premises true? (i.e., is the argument sound, cogent?)
Lecture 5 / Argument Forms
I. Argument Forms – proving invalidity of deductive arguments
II. Extended arguments
I. Argument Forms
Deductive argument
 Conclusion necessarily follows from premises
 Conclusion does not give new information.
 Why? Validity of such arguments is given by the form, not the content of the
statements
Example
All adlers are bobkins.
All bobkins are crockers.
Therefore, all adlers are crockers.
No matter what adlers, bobkins and crockers are, this argument is valid.
How to create an argument form?
By consistently substituting letters for terms in an argument.
All Adlers are Bobkins
All Bobkins are Crockers
Therefore, all Adlers are Crockers
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All A are B
All B are C
Therefore, All A are C.
 Whatever you substitute for A, B, C, the argument will remain valid.
 A – cats, B – mammals, C – animals
 A – humans, B – persons, C – subjects with rights
Substitution instance – argument that is produced by uniformly substituting words for letters
in an argument form.
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All A are B
All B are C
All A are C
Argument form
All cats are mammals
All mammals are animals
All cats are animals
Substitution instance
Proving invalidity
 Consider argument:
All adlers are bobkins
All crockers are bobkins
Therefore, all adlers are crockers
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Is it valid or invalid?
What is the form of the argument?
Proving invalidity
 All A are B.
All C are B.
Therefore, all A are C.
 Remember: argument is invalid, if assuming the premises are true, the conclusion can
be false.
Therefore: if you find a substitution instance with clearly true premises and
clearly false conclusion, you prove the argument invalid.
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A – cats, B – animals, C – dogs
All cats are animals T
All dogs are animals T
Therefore, all cats are dogs F
 If this substitution instance is invalid, then the original adler-bobkin-crocker argument
is also invalid, because they share the same form.
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Counterexample method
 Counterexample – a substitution instance with clearly true premises and clearly false
conclusion.
 Counterexample method of proving invalidity of deductive arguments – method of
finding counterexamples.
 Can be only used to prove invalidity, not validity – the only arrangement that proves
something about validity is true premises, false conclusion.
 Can be only used with deductive arguments, because their validity depends on the
form. Strength of inductive arguments depends also on the content.
Example 1
 Since some employees are not social climbers and all vice-presidents are employees,
we may conclude that some vice-presidents are not social climbers.
 What is the form of the argument?
Example 2
 Some E are not S.
All V are E.
Therefore, some V are not S.
 Find terms that could be substituted for E, S and V and give true premises and false
conclusion
Example 3
 E – animals
S – mammals
V – dogs.
 The resulting substitution instance is:
Some animals are not mammals.
All dogs are animals.
Therefore, some dogs are not mammals.
T
T
F
Advice
 There is no uniform way of producing counterexamples
 Use some simple terms – cats, dogs, animals, mammals, fish – these could help you
find most counterexamples.
 Begin with a false conclusion and then construct true premises.
Hypothetical syllogisms
 Categorical syllogisms analyze relationships between terms in sentences
 Hypothetical syllogisms between whole sentences:
 If the government imposes import restrictions, the price of cars will rise. Therefore,
since the government will not impose import restrictions, the price of cars will not rise
 If G, then P
Not G
Therefore, not P.
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
G – Abraham Lincoln committed suicide.
P – Abraham Lincoln is dead
 Substitution instance:
If Abraham Lincoln committed suicide, then Abraham Lincoln is dead
Abraham Lincoln did not commit suicide
Therefore Abraham Lincoln is not dead.
T
T
F
Advice
 Conditional statement in the premise – must be true – select some statements with a
necessary connection : suicide – death, water – wet…
 Conditional statement in the conclusion – must be false – antecedent must be true and
consequent false: If Klaus is the President, then Klaus is the Interior Minister.
Lecture 6 / II. Extended arguments
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Arguments in newspapers, magazines and ordinary speech may be very complex –
arguments, sub arguments, multiple conclusions, conclusions serving as premises, etc.
For the sake of clarity, the form of extended arguments must be analyzed
Types of argument structure
 Vertical pattern
 Horizontal pattern
 Conjoint premises
 Multiple conclusions
Vertical pattern
 The conclusion of a prior argument becomes a premise of another argument
 (1) The selling of human organs should be banned.
(2)Allowing human organs to be sold will lead to a situation in which only the rich
will be able to afford transplants. This is so because
(3) whenever something scarce is bought and sold as a commodity, the price always
goes up.
(4)The law of supply and demand requires it.
(4)
↓
(3)
↓
(2)
↓
(1)
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Horizontal pattern
 Conclusion supported by more independent premises
 (1)The selling of human organs should be banned.
(2) If it is allowed, people in financial need will start selling their organs.
Also, (3) criminals will start killing healthy young people and sell their organs on
black market.
(2)
(3)
(1)
Conjoint premises
 Two or more premises, which independently give little or no support to conclusion,
but together give substantial support.
 (1) Whenever it is raining, it is wet.
(2) It is raining.
Therefore, (3) it is wet.
(1)
(2)
(3)
Multiple conclusion
 Strictly speaking each argument has only conclusion. This is a simplification.
 (1) Dropping out of school and bearing children outside of marriage are two of the
primary causes of poverty in this country.
(2) Therefore, to eliminate poverty we must offer incentives for people to get high
school diplomas.
(3) Also, we must find some way to encourage people to get married before they start
having children.
(1)
(3)
(2)
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Cognitive and emotive meaning
 Ordinary language serves a lot of functions
o Ask questions
o Tell stories
o Tell lies
o Tell jokes
o Flirt
o Command
o Persuade
o Greet
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Two functions crucial for argumentation:
o To convey information
o To evoke feelings

The death penalty, which is legal in thirty-six states of USA, has been carried out most
often in Georgia. However, since 1977 Texas holds the record for the greatest number
of executions.
The death penalty is a cruel and inhuman form of punishment in which hapless
prisoners are dragged from their cells and slaughtered only to satiate the bloodlust of
a vengeful public.
Cognitive meaning – words are used to convey information (death penalty, legal,
carry out, execution). Neutral, provided by dictionary definitions.
Emotive meaning – words are used to evoke feelings (cruel, hapless, dragged,
slaughtered, satiate the bloodlust)
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Bureaucrat – government official – public servant
Censorship – editorial review – screening, filtering
Ghetto – economically deprived area – economic development area
Primitive countries – third world countries – developing countries

Emotively charged statements and expressions have both cognitive and emotive
meaning.
These two must be distinguished – logic only deals with cognitive meaning.
Part of the cognitive meaning of emotively charged statements is a VALUE CLAIM.
o The statement about the death penalty in fact implicitly asserts that death
penalty is immoral or wrong.
We must find the value claim and make it explicit
o it may be vital for the argument.
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
Why do people hide value claims in emotive language instead of stating them
explicitly?
o Value claims require evidence. Emotive language may be a trick to obscure the
fact that a value claim is being made. It may thus be swallowed by readers
without evidence.
o It may show the inability of the speaker to provide any rational arguments.
o It may purposefully appeal to the emotions of readers, avoiding their rational
judgment and thus manipulate readers.
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Example
Footbinding in China was first banned in 1912. But some continued binding their feet in
secret. Some of the last survivors of this barbaric practice are living in Liuyicun, a
village in Southern China's Yunnan province.
The speaker is giving 2 different kinds of information. What are they?
1. Footbinding was banned in China in 1912. Some continued the practice in secret. Some
survivors still live in Southern China
2. Footbinding is wrong (implied by the expression „barbaric practice“)
Watch out! The speaker may be trying to pass off a controversial value judgment without
an argument.
Emotive meaning as a source of manipulation
 Advertisement
o Texaco is the star of the American Road
o Farm insurance is like a good neighbor.
o Orion – vaše čokoládová hvězda
o Calibrum – síla mocného kalibru
o Dobrá voda – příroda regeneruje
 What are the emotions associated with „star“, „good neighbor“, „kalibr“,
„regenerace“?

Manipulation by using euphemisms
 Euphemism – an expressions with a milder meaning used instead of an expression
with the appropriate meaning.
 Military
o Human targets – soft targets
o Napalm – soft ordnance
o Dropping bombs – servicing a site
o Saturation bombing – terrain alteration
o Concentration camp – pacification center
o Torture – enhanced interrogation
o War – police action, conflict
Emotive terminology in arguments
 If you find emotive expressions in an argument, you must interpret their meaning and
put them in the form of an explicit value judgment, i.e. state it clearly as a premise of
the argument in an emotionally neutral way.

Would it be so terrible if there were no slaughterhouses filled with stinking bloody
carcasses? Would our lives be poorer if no animals writhed in steel-jaw leg hold traps?
Would we fare so badly by wearing natural fabrics instead of furs and leathers? How
bad could it be for our children if they did not witness the pithing of frogs in their
classrooms? How dearly would we miss watching a bull´s chest being pierced and its
ears cut off? Who could object to a medical science that advanced prevention and
healthy lifestyles instead of vivisecting living animals?
P1: The condition under which animals are converted into distasteful.
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P2: We would be no worse off if we did not depend on animals for food
P3: The fur industry traps animals in the wild.
P4: The traps cause great pain to animals.
P5: It would be better if our children did not witness the pithing of frogs in the
classroom.
P6: Bullfights cause great pain to the bull.
P7: The entertainment provided by bullfights is not really important to us.
P8: Medical science can get along without experimenting on animals
C: Our use of animals for food, clothing, entertainment and medical experimentation
is wrong.
Verbal and factual disputes
 When two people disagree about the facts – FACTUAL DISPUTE.
 A: The accident happened because the red car did not yield.
B: No way! It happened because the blue car was driving too fast!

When people disagree about the cognitive meaning of a word (i.e. its proper
definition) – VERBAL DISPUTE
 A: Tomorrow I am going to Offspring concert. Their music is fabulous.
B: You call that music? It´s just noise, incredibly loud noise!
Lecture 8 / Basic inductive arguments and their evaluation
Basic inductive arguments
 Appeal to authority
 Argument ad hominem (against the person)
 Argument from analogy
Appeal to authority
 An argument in which the conclusion is justified by the fact that it is endorsed by a
supposed authority, expert, knowledgeable person or a group of people.

P1
X claims that P
C
P

Such high investments in armament will inevitably lead to an economic disaster.
Einstein claims that enormous armament investments are a sigh of political instability
and can postpone the end of recession.
 A: The kid is gifted, so he will do music.
B: Well, but it also requires some determination. I’ve recently read Koukolik and he
claims that talent contributes only five percent to the success of the carrier.
 I think it is necessary to eat a lot of vegetables and avoid meat. My neighbor, who
worked in health care for twenty years, claims that after the age of thirty you don’t
need meat at all and moreover it is bad for you.
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Evaluation of appeal to authority
 1. Is the person appealed to an expert in the given field?
 An expert can in a given situation be e.g.:
o Someone with sufficient knowledge
o Someone with access to information
o A witness
o A sick person
o A child
o An unbiased person


2. Does the person’s statement correspond to his or her beliefs? Is there a
suspicion that the person has been bribed, manipulated, put pressure on,
emotional?
„No-one is a good judge in his own cause“

3. What are other experts’ opinions?

4. Has the statement been understood, interpreted, cited, etc. correctly?
Expert: An extract from marihuana can be used to treat some gallbladder diseases.
Ordinary person: Experts have proved that marihuana is good for you.

Is it sufficiently clear whose words are being cited?
„The best dentists recommend….“
„It is generally accepted…“
Examples
 Give an example of a situation in which:
o the expert can be a small child.
o it is not sufficient to be unbiased to be an expert.
o it is not sufficient to be a witness to be an expert.
 What characteristics does a person have to have to be considered an expert in: nuclear
physics, driving, women fashion, gender equality, manipulation with people, adding
one-digit numbers, setting up a football team, the existence of God, telling apart
experts and non-experts.




Give an example of a field in which there are no reliable experts.
Give an example from history in which the consensus of experts was mistaken.
Are there examples of fields in which the experts differ in opinions? What can cause
such disagreement?
How to create an impression that I am an expert when I am, in fact, not?
Argument ad hominem
 Argument in which one disputes a person’s statement by attacking the characteristics
of the person, e.g. behavior, world view, origin, sex, etc.). One does not, thus, argue
directly against the statement, but against the person making the statement and only
indirectly against the statement or the whole argumentation of the person.
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Examples
 The chairman Laker claims that the government policies will destroy agriculture. But
Laker is a fool who has no idea about economy.
 Do you think that love is sufficient for happines? I thought so as well, when I was
your age.
 You say smoking is bad for you and still you smoke.
Kinds of ad hominem - Type 1
 A reference to the insufficiency in objectivity, competence, etc. of the person.
Sachs claims that Free Masons secretly controlled all major events of the 19th and
20th centuries, but he is not able to give the dates of the Franco-Prussian war, knows
nothing about the Sarajevo Assassination and has never heard of the Great Crisis of
the thirties.
 Evaluation
o this is the converse of the appeal to authority argument. One can use the same
criteria
- expert?
- accordance with belief?
- other experts?
o we examine if the attacked characteristics are relevant to the reliability of the
criticized statement:
o Mr. X claims that Sommertur is an insurance company that offers the best
insurance conditions. However, Mr. X is firstly not an economist, but an actor,
and therefore does not probably understand insurance business very much.
Moreover, I have read in the papers that he has been given over a hundred
thousand for the advertisement campaign.
o …sures are wrong and meanwhile Mr. X’s mother’s cousin’s wife is in prison
for fraud.
Exercises
 Give an example of a justified ad hominem argument attacking the :
o opponent’s low income,
o opponent’s age,
o place of residence,
o job
o sex
o ugliness
Kinds of ad hominem - type 2
 Contradiction between the opponent’s opinions and acts
o MP Kadera demands a halt to the construction of hypermarkets in towns. But
the papers say that last weekend Kadera was seen doing his shopping in Tesco.
o You claim that telling lies is always wrong and nevertheless you lied yourself,
when…
 Evaluation – deciding if there really is a contradiction between the person’s claims and
their acts.
o Is there really a contradiction between rejecting the construction of
hypermarkets and shopping in Tesco?
o Is there really a contradiction between saying that every lie is bad and lying?
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Argument from analogy
 Argumentation is based on the similarity of two objects, situations, acts, etc.
o Since we call bin Laden a terrorist for the reason that his organization has
killed many innocent people in their attacks, it would be fair to call president
Bush a terrorist, too. When he ordered the attack of Afghanistan, he caused the
death of thousands of innocent victims.
o If the vaccine worked with rats, whose immune system is similar to human’s, it
will also work with people.

General structure:
Object A has characteristics P, Q, R…. and Z
Object B has characteristics P, Q, R
Therefore, object B also has the characteristic Z


Claim: It is wrong to kill animals, since it is wrong to kill people.
Object A – man – characteristics: living organism, perception of pain, experience
pleasure, killing deprives them of potential pleasures, therefore, it is wrong to kill a
man.
Object B – animal – characteristics: living organism, perception of pain, experience
pleasure, killing deprives them of potential pleasures.
Therefore, it is also wrong to kill an animal.


Evaluation of the argument from analogy
 Consists in evaluating the similarity between the compared objects. The similarity
must be based on substantial characteristics and there must not be any substantial
differences.
Example
 Car A is white, has upholstered steering wheel and two airbags. It also has low fuel
consumption.
 Car B is also white, has upholstered steering wheel and two airbags. It is therefore
probable that it also has low fuel consumption.
 The compared characteristics of the cars are not substantial characteristics, since
their possession does not lead with a high degree of probability to ty to the possession
of the questioned



Car A has a small volume engine, aerodynamic design and correctly inflated tires. It
also has low fuel consumption.
Car B also has a small volume engine, aerodynamic design and correctly inflated tires.
Therefore, car B probably has low fuel consumption, too.
The cited characteristics are substantial with respect to the consumption of fuel. The
argument is strong, provided there is not a hidden substantial difference, e.g. the
weight of the car.
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Analysis consists in the following steps:
A. analyze the structure:
1. What are the compared objects?
2. What are the undisputed characteristics of object A?
3. What are the undisputed characteristics of object B?
4. What are the disputed characteristics of object B?
B. decide if the undisputed characteristics are substantial for the possession of the
disputed characteristics
C. decide if there is a substantial difference between the two objects.
Exercises
Evaluate these arguments:
 1. Imagine that one day you are kidnapped by the Music Lovers Club and learn that
you must donate blood to an exceptional violinist, whole kidneys have failed.
Moreover, you will have to provide you service for nine months. It would be kind and
generous of you to accept that, but you are not obliged by a moral obligation.
Pregnancy is no different from such a situation. The right of the woman for her own
body is more important than the right to exist of xist of the fetus.
 2. Imagine you are traveling in the desert and you find a watch in the sand. You
examine it carefully and see the ingenious character of the mechanism. Its parts are
made precisely and assembled to co-operate in a unified system with a particular goal.
Even if you had never seen a watch in your life and did not know their purpose, you
would have to conclude on the basis of such an examination that it is a purposely
designed device. When we observe even more ingenious constructions of the Nature,
the conclusion about their purposeful design should be even more apparent.
 3. Many more people get killed in traffic accidents than in drug overdose. If we do not
ban driving, why should we ban drug consumption?
 Since we call bin Laden a terrorist for the reason that his organization has killed many
innocent people in their attacks, it would be fair to call president Bush a terrorist, too.
When he ordered the attack of Afghanistan, he caused the death of thousands of
innocent victims
 Since the government should educate the citizens, it cannot be democratically elected.
Students do not choose their instructors, either.
26
Lecture 9 / Argument from analogy
Further factors influencing strength
Analogy:
Object A (primary analogate)
Object B (secondary analogate)
Properties:
Properties:
-p
-p
-q
-q
-r
-r
-z
- z???















Jane wants a new car. She wants a car with low fuel consumption. Jack has a Chevy. It
has low fuel consumption. Jane argues:
- Both cars are white, have electronically controlled windows and 300 liter boot.
Therefore, since Jack’s has low consumption, mine will have, too.
Is the analogy strong or weak?
SUBSTANTIALITY OF SIMILARITIES, i.e. the compared properties must be
relevant to the required property.
Jane also notes she uses air conditioning a lot, while Jack does not. She drives in city,
while Jack drives long distances on interstate highways. She likes rapid starts and
screeching stops, while Jack drives smoothly.
Is the analogy stronger or weaker?
Existence of SUBSTANTIAL DIFFERENCES weakens analogies.
Jane also finds 5 other similarities:same- size engine, weight, aerodynamic body, gear
ration, and tires.
Is the analogy stronger or weaker?
The higher the NUMBER OF SIMILARITIES, the stronger the analogy
Jane finds that three other friends have the same model of car and they also have low
consumption of fuel.
Is the argument stronger or weaker?
The NUMBER OF PRIMARY ANALOGATES strengthens the argument.
Jane finds another friend who has the same model, but has a very high consumption.
COUNTERANALOGY weakens analogy.
All of Jane’s friends buy gas at the same station, use the same mechanic, use the same
additives in the oil, inflate the tires to the same pressure.
ment stronger now?
ITY BETWEEN PRIMARY ANALOGATES weakens the analogy. DISSIMILARITY
ITY BETWEEN PRIMARY ANALOGATES he analogy, because it eliminates the
possibility that the questioned property – fuel consumption – is caused by other factors
that are not essential to to the model of the car.
model of the car.
…..vadny pdf subor s prednaskami 
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



Jane changes her mind: instead of LOW consumption, she now wants AT LEAST
AS LOW consumption as Jack.
Is the argument stronger?
Increased SPECIFICITY of the conclusion weakens the argument.
If Jane wanted THE SAME consumption as Jack’s, the argument would be further
weakened. The more specific the conclusion is, the weaker the analogy becomes.
Conclusion
 The strength of an analogy is influenced by:
substantiality of similarities ↑
number of similarities ↑
existence of substantial differences ↓
number of primary analogates ↑
similarity of primary analogates
specificity of conclusion ↓
Example
 Rebecca wants to buy a new TV set. She notices that her friend Anastasia’s new Sony
gets the best picture she has ever seen. She reasons: if I buy the same model as
Anastasia, I will get the same quality picture.
 Does the following information strengthen her argument, or weaken?
1. The model Rebecca is planning to buy has the same-color cabinet, same-size
loudspeakers, the same remote control, and the same stand as Anastasia’s model.
2. The model Rebecca is planning to buy has the same picture tube and the same
electronic circuitry as Anastasia’s.
3. Rebecca plans to use the rabbit-ear antenna that comes with the set. She lives in a
fourth-floor apartment in Manhattan, while Anastasia lives in a seventieth-floor
apartment.
4. Anastasia’s transmission is supplied by a cable company.
5. Rebecca changes her mind and decides to hook up with the same cable company
as Anastasia.
6. Rebecca knows of five other people who own the same Sony model as Anastasia
and who get approximately the same picture quality..
7. These five people live in the same building.
8. Rebecca discovers four different people who live in various parts of Manhattan,
have the same model of Sony and get approximately the same quality picture as
Anastasia.
9. Rebecca changes her conclusion to state that she will get at least as good a picture
as Anastasia.
10. Rebecca changes her conclusion to the state that she will get exactly the same
picture as Anastasia.
Revision

Define the following expressions:

argument, statement, premise, conclusion, conclusion indicator, premise indicator,
inference, truth value

conditional statement, antecedent, consequent, explanation, explanandum,
explanans
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




True or false?
Any passage that contains an argument must contain a claim that something is
supported by evidence or reasons.
Such claim is always explicit.
Passages that contain indicators thus, since, because are always arguments.
In an explanation, the explanandum usually describes an accepted fact.

Define:
deductive argument, inductive argument, argument based on mathematics,
argument from definition, categorical syllogism, hypothetical syllogism,
disjunctive syllogism, inductive generalization, argument from analogy,
prediction, argument from authority, argument based on signs, causal inference


True or false?
In an inductive argument, it is intended that the conclusion contain information not
contained in the premises.
The nature of the link between premises and conclusion may allow one to determine if
an argument is inductive or deductive.
Most arguments based on statistical reasoning are deductive
An argument that draws a conclusion about a thing based on that thing’s similarity
something else is a deductive argument.
If an argument contains the phrase “it definitely follows that”, we can conclude that it
is deductive.
If a deductive argument has true premises and false conclusion, it is necessarily
invalid.
A valid argument may have false premises and false conclusion.
A sound argument may have a false conclusion.
A cogent argument must be inductively strong.
If an argument has true premises and false conclusion, we know it is a perfectly good
argument.










Define
- argument form, substitution instance, counterexample, cognitive meaning, emotive
meaning, value statement
- What should you do, if you find an emotive expression in an argument?
- How do you evaluate arguments from authority?
- How do you evaluate arguments ad hominem?
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Lecture 10 / Logical fallacies
FORMAL FALLACIES
 Brown would have signed such a risky contract, if he had trusted our company. As you
know, he eventually signed the contract, so he trusted our company.
 What is the form?
 Find a counterexample

If p, then q
q
Therefore, p
 Counterexample
If I like apples, then I like fruits.
I like fruits.
Therefore, I like apples
 AFFIRMING THE CONSEQUENT



If the new employee is a “party animal”, she will definitely join us tonight. But I’ve
heard she is rather reserved. So she will not join us tonight.
What is the form?
Find a counterexample

If p, then q
Not p
Therefore, not q
 Counterexample
If Alex is a man, he is human.
Alex is not a man
Therefore, Alex is not human.
 DENYING THE ANTECEDENT

If I like apples, I like some fruits.
I like apples
Therefore, I like some fruits
 What is the form?
 Is it a valid form?
 HYPOTHETICAL SYLLOGISM – MODUS PONENS




If Peter is a Civic Democrat, he is in favor of free market economy.
Peter is not in favor of free market economy.
Therefore, Peter is not a Civic Democrat.
What is the form?
Is it a valid form?
HYPOTHETICAL SYLLOGISM – MODUS TOLLENS
30



VALID FORMS
modus ponens:
if p, then q
p
therefore, q
modus tollens
if p, then q
not q
therefore, not p


INVALID FORMS
affirming the consequent
if p, then q
q
therefore, p
denying the antecedent
if p, then q
not p
therefore, not q
INFORMAL FALLACIES / Fallacies of relevance
Fallacies of relevance: premises are logically irrelevant to the conclusion. However, they
frequently are relevant psychologically, therefore the argument may appear convincing or
persuasive.
Appeal to force
 Instead of offering legitimate premises for a conclusion, the arguer threatens to use a force
if the recipient does not accept the conclusion
 Secretary: I deserve a raise in salary for the coming year. After all, you know how friendly
I am with your wife, and I am sure you would not want her to find out what has been
going on between you and that sexpot client of yours.
Appeal to pity
 Arguer poses a conclusion and then attempts to evoke pity from the listener.
 Taxpayer to judge: Your Honor, I admit that I declared thirteen children as dependents
on my tax return, even thought I have only two. But if you find me guilty of tax
evasion, my reputation will be ruined. I will probably lose my job, my poor wife will
not be able to have the operation that she desperately needs, and my kids will starve.
Appeal to people
 Direct approach: the arguer tries to excite emotions and enthusiasm of the crowd to
win acceptance of their conclusion. Used by propagandists and demagogues.
 Indirect approach: focuses not on the crowd, but on an individual and his or her
relationship to the crowd. Often used in advertising industry:
 Bandwagon argument –
o Of course you want to buy the new Colgate toothpaste. Why, 90 percent of
America brushes with Colgate.
o You will be left behind if you do to use the product
 Appeal to vanity – associates product with a celebrity who is admired and pursued.
The idea is if you use the product, you will also be admired and pursued.
 Appeal to snobbery
o Rolls Royce is not for everyone. If you qualify as one of the select few, this
distinguished classic may be seen and driven at British Motor Cars, Ltd. (By
appointment only, please)
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Argument ad hominem (proti osobě)
 See previous lecture. Ad hominem arguments are mostly fallacious, but when the
premises are relevant to the conclusion, they can be strong.
Accident (náhoda)
 When a general rule is applied to a specific case which it is not meant to cover, but
which accidentally shares some characteristics with the cases the rule covers.
 Freedom of speech is a constitutionally guaranteed right. Therefore, John Q. Barrows
should not be arrested for his speech inciting terrorist attacks.
 Property should be returned to its rightful owner. That drunken sailor who is starting a
fight with his proponents at the pool table lent you his .45 caliber pistol, and now he
wants it back. Therefore, you should return it to him.
Straw Man (strašák)
 A person instead of arguing against the opponent’s argument distorts it and knocks
down the distorted version.
 Mr. Goldberg has argued against prayer in the public schools (argument). Obviously
Mr. Goldberg advocates atheism (distortion). But atheism is what they used to have in
Russia. It leads to the suppression of all religions and the replacement of god by an
omnipotent state (knock-down of distorted argument). Clearly Mr. Goldberg’s
argument is nonsense.
Red Herring (falešná stopa)
 The arguer diverts the attention of the reader or listener by changing the subject to
some totally different issue.
 Your friend Margie says that Taster’s Choice coffee tastes better than Folgers.
Apparently she is ignoring the fact that Tasters Choice is made by Nestle, and Nestle
is the company that manufactured that terrible baby formula for third world countries.
Thousands of babies died when the dry milk formula was mixed with contaminated
water. Obviously your friend is mistaken.
Straw Man vs. Red Herring
 In Straw Man the arguer misinterprets the opponent’s argument, i.e. builds another
argument, usually one that is more extreme and easier to refute, and then knocks it
down.
 In Red Herring no other argument is built and knocked down. The arguer simply starts
talking about a different topic to make the opponent forget about the previous problem
and start arguing about the new problem. The arguer simply changes the subject.
Missing the point (nepochopení pointy)
 When an arguer draws a different conclusion than the one that logically follows from
the premises.
 Crimes of theft and robbery have been increasing at an alarming rate lately. The
conclusion is obvious: we must reinstate the death penalty.
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Lecture 11 / Informal fallacies II - Fallacies of weak
induction
fallacy of weak induction
 fallacy of relevance – when premises are irrelevant to the conclusion
 fallacy of weak induction – when premises do not give sufficient support to the
conclusion
1. Appeal to unqualified authority
 Appeal to authority – the conclusion is accepted because an authority accepts it.
 P1: X accepts that P
C: Therefore, P
 For the argument to be successful, the cited authority must be an expert in the field.
 When the authority is not trustworthy, the argument is fallacious
Untrustworthiness
 person lacks expertise in the field
 person is biased
 person has a motive to misinform
 the person does not have the requisite abilities to perceive or recall information
2. Appeal to ignorance
 The premises state that nothing has been proved one way or the other about
something, and the conclusion makes a definite assertion about that thing. The issue
usually involves something that has not yet been proved or is incapable of being
proved.


People have been trying for centuries to provide conclusive evidence for the claims of
astrology, and no one has ever succeeded. Therefore, we must conclude that astrology
is a lot of nonsense.
People have been trying for centuries to disprove the claims of astrology, and no one
has ever succeeded. Therefore, we must conclude that the claims of astrology are true.
Exceptions
 if qualified researchers investigate a certain phenomenon within their range of
expertise and fail to turn up any evidence that the phenomenon exists, the fruitless
search constitutes strong evidence that the phenomenon does not exist.
 courtroom procedure – if nothing is proved beyond reasonable doubt, the person is
not guilty (“not guilty” is legally defined that guilt has not been proved beyond
reasonable point, not that the person did not commit the crime)
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3. Hasty generalization
 Converse accident
 Happens with inductive generalization
 When the sample group is not representative or is too small
 After only one year the alternator went out in Mr. Grady’s new Chevy. Mrs. Dodson’s
Oldsmobile developed a transmission problem after six months. The conclusion is
obvious that cars made by GM are just a pile of junk these days.
Exception
 Some generalizations based on a small sample may be strong:
 Ten milligrams of substance Z was fed to four mice, and within two minutes all four went
into shock and died. Probably substance Z, in this amount, is fatal to the average mouse.
 In this case there is no reason to think that the sample is atypical of the group. If that is so,
such argument may be strong.
4. False cause
 The link between the premises and the conclusion depends on some imagined causal
connection that probably does not exist
Varieties
a) coincidental occurence
o During the past two months every time that the cheerleaders have worn blue
ribbons the team has been defeated. Therefore, to prevent defeats in the future the
cheerleaders should not wear blue ribbons
- Here the fact that the defeat occurs after the cheerleaders wear the ribbon
is mistaken for the fact that the ribbons cause the defeat.
o Successful business executives are paid salaries in excess of $ 50,000. Therefore,
the best way to ensure that Ferguson will become a successful executive is to raise
his salary to at least $ 50,000.
- Here the result is mistaken for the cause
o There are more laws in the books today than ever before, and more crimes are
being committed than ever before. Therefore, to reduce crime we must eliminate
the laws
- Here the coincidence is taken to be a causal relationship
b) oversimplified cause
o When what is taken to be the sole cause of an event is in fact only part of the
cause.
o The quality of education in our high schools has been declining for years. Clearly,
our teachers just are not doing their job these days.
- Here the cause of the decline in the quality of education is definitely more
complex than just the incompetence of teachers.
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5. Slippery slope
 The conclusion depends on an alleged chain reaction that is unlikely to occur.
 Immediate steps should be taken to outlaw pornography once and for all. The continued
manufacture and sale of pornographic material will almost certainly lead to an increase in
sex-related crimes such as rape and incest. This in turn will gradually erode the moral
fabric of society and result in an increase in crimes of all sorts. Eventually a complete
disintegration of law and order will occur. leading in the end to the total collapse of
civilization.
 The argument is that the first step will with a high degree of probability lead to the last
step via a chain of highly probable causes. It is disputable, if the whole chain is highly
probable, though.
 Consider one common argument against the legalization of marihuana – it is the first step
to hard drugs.
6. Weak analogy
 Analogy is weak when:
- the compared properties of analogates are irrelevant
- there are few similar properties between analogates
- there are substantial differences between analogates
Lecture 12 / Other fallacies
Begging the Question
 Ford Motor Company clearly produces the finest cars in the US. We know they produce
the finest cars because they have the best design engineers. The reason why they have the
best design engineers is because they can afford to pay them more than other
manufacturers. Obviously, they can afford to pay them more because they make the finest
cars in the us.
 Identify the conclusion and draw the argumentation scheme.
 In Begging the Question the arguer
- assumes in the premises what is supposed to be proved (may be using slightly
different vocabulary)
- assumes in the premises a statement that is at least as problematic as the
conclusion
- ignores a questionably true premise.
 God exists because Jesus was resurrected.
 Murder is morally wrong. Therefore, abortion is morally wrong.
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Complex question
 Have you stopped beating your wife?
 Where did you hide the cookies you stole?
o What happens, if you answer yes? What happens, if you answer no?
o Some questions presuppose certain facts. If the facts do not hold, the question
loses sense. Here you presuppose that the person has been beating his wife and that
they have stolen the cookies.
o In fact, complex questions include two questions:
- Have you been beating your wife?
- Have you stopped doing it?
- Did you steal the cookies?
- Where did you hide them?
False Dichotomy
 Either you use Ultra Guard deodorant or you risk the chance of perspiration odor. Surely,
you don’t want to risk the chance of perspiration odor. Therefore, you will want to use
Ultra Guard deodorant.
 Either I continue smoking, or I will get fat and you will hate to be seen with me.
 The first premise is a disjunctive statement – either/or
 The second premise is one disjunct is undesirable
 The conclusion is we must necessarily accept the other disjunct.
 The fallacy is that the disjunctive premise pretends there are only two alternatives when,
in fact, there are more.
Suppressed Evidence
 Most dogs are friendly and pose no threat to people who pet them. Therefore, it would be
safe to pet the little dog that is approaching us now.
 Used car salesman to buyer: Mrs. Webb, I have just the car you need. this 1988 Cevy was
recently traded by a little old lady who kept it in the garage most of the time. the odometer
read low mileage, and the engine has recently been tuned up. If you buy this car, it will
give you trouble-free service for years
 The arguments are strong only if they do not ignore some important piece of evidence:
- the dog is excited and foaming at mouth (rabies)
- the lady drove the car cross-country, odometer had rolled around twice, engine has
two cracked pistons and burned valve.
 If such important evidence is suppressed, the arguer commits a fallacy and the argument is
weak.
For more information on logical fallacies see e.g.
http://cs.wikipedia.org/wiki/Logický_klam
http://www.nizkor.org/features/fallacies/
http://www.unc.edu/depts/wcweb/handouts/ fallacies.html
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Lecture 13 / Debate
Debate
 an exchange of opinions based on argumentation
 the aim is to formulate, analyze and defend one’s opinion and rebut your opponents
opinion.
 necessary skills – critical thinking, listening to your opponent
Principles of debating
1. respecting your opponent
- no ad hominem arguments
- no showing of disrespect
- no verbal pressure
- compare: “How could anybody think such nonsense” x “I can see your view but I think it
is dissatisfactory”
- the point of the debate is to get as many perspectives as possible – not to win your
position if it is unjustified.
2. listening carefully to what the opponent says.
- what is my opponents opinion?
- what kind of arguments does my opponent use?
- what is my opponent’s best argument?
- what kind of argument is it? deductive? inductive? valid? sound? strong? cogent?
- is my opponent using logical fallacies to win a point?
- are my opponent’s answers relevant?
3. reacting to my opponent’s arguments
- make sure you interpret opponent’s position correctly
- for that matter rephrase your opponent’s argument in your own language
- think about how you can attack their arguments –by showing it contains a fallacy?
irrelevance? showing it is inductively weak?
- when you answer your opponent’s argument, present yours
Presenting your argument
 choose a few strong arguments rather than a lot of weak ones.
 use them the following way:
1. very strong argument
2. weak arguments
3. the strongest argument
 avoid making fallacies – if you do not discover them in your argumentation, your
opponent will
 use signaling phrases:
- to defend my position
- let us look at the problem from a different perspective
- I would like to focus your attention to another problem
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Presentation
 never interrupt your opponent
 stand up when speaking
 look straight in the eyes
 use gestures and useful body language
 use your voice – intonation
 if you can, be funny
Seminar debate
 get in two groups
 put together your arguments
 choose the best ones
 select the speaker who will open the debate by defining the thesis and their position
 opponent will repeat the position, anwer the argument and present their position
 speakers from the opposing sides take turns
Lecture 14 / Summary of the subject matter
- opakovanie…
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