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Concept
Analysis
Breaking down an idea, concept, theory, etc. into its
most basic parts in order to get a better understanding
of its structure.
• This is necessary to evaluate the merits of the claim
properly (is it a fact, probably true, possibly true,
impossible?).
Concept
Analysis
We begin with identifying the basic components of any
argument:
•argument indicators
• premises
• conclusions
• assumptions
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1. All men are mortal
2. Socrates is a man
Therefore, Socrates is mortal
Anatomy of an Argument
Proposition: A statement or
sentence that declares
something to be true. (It
is snowing outside,
killing people is wrong,
there is an invisible
dragon in my garage).
Premise: Any proposition
used as evidence to
support another
proposition.
1. All men are mortal
2. Socrates is a man
Therefore, Socrates is mortal
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Anatomy of an Argument
Inference: An inference is
the move one makes from
reasons to a conclusion.
• When we conclude that
something is true in the
light of some set of
reasons we have made an
inference. Inferences can
either be justified (valid)
or unjustified (invalid)
depending on what
support the reasons give
to the conclusion.
1. All men are mortal
2. Socrates is a man
Therefore, Socrates is mortal
Premise
1. All men are mortal
2. Socrates is a man
*inference*
Therefore, Socrates is mortal
Conclusion
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Concept
Analysis: Argument indicators
Argument indicators: language that commonly indicates
the presence of reasons or conclusions.
1. conclusion indicators: words that point to a
conclusion that has been reached.
Examples: “Therefore…”
•So
•Hence
•Consequently
•Which Proves…
•Which Establishes…
•Justifies the view that…
•In conclusion
•From which we can infer…
•It follow that…
•Demonstrates that…
Concept
Analysis: Argument indicators
Argument indicators: language that commonly indicates
the presence of reasons or conclusions.
2. reason indicators: words that point to a reason
that has been offered in support of a conclusion.
Examples: “because…”
•Since
•For
•Follows form the fact that
•The reasons are
•First, second, etc.
•If…then
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Concept
Analysis: Checking for assumptions
Check for assumptions. In your analysis could you find any
assumptions…
a) That seem likely in the context
b) Which must be added to the argument to make sense
of what is said
c) Which seem necessary to make the reasoning as strong
as possible.
Concept
Analysis: Argument Key
<Reasons/Premise>
[Conclusions]
Argument indicators
Assumptions:
<I want you to be strong, confident
Independent thinkers> so [I’m teaching
You how to analyze arguments]
Assumption:
•analyzing arguments will make
Someone a strong, etc. thinker (stated)
• That you are not already actively doing
these things (unstated)
Will be written out
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Concept
Analysis: diagramming arguments
Arguments can get very long and complicated. When this happens it is useful to
construct a diagram of the argument to illustrate how the premises support the
conclusion.
Argument Patterns:
1. Vertical Pattern
or chain.
The premise directly supports a conclusion
which can become the premise for another
conclusion further down the chain. Each link
in the chain depends on the others.
Concept
Analysis: diagramming arguments
Arguments can get very long and complicated. When this happens it is useful to
construct a diagram of the argument to illustrate how the premises support the
conclusion.
Argument Patterns:
2. Horizontal Pattern
In a horizontal pattern each premise
supports the conclusion independently
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Concept
Analysis: diagramming arguments
Arguments can get very long and complicated. When this happens it is useful to
construct a diagram of the argument to illustrate how the premises support the
conclusion.
Argument Patterns:
3. Conjoint Premises
When two or more premises support a
Conclusion conjointly. On it’s own, neither
Premise would lend any support to the conclusion.
But together they can lend support.
*this relationship can be reversed where one
Or more Premises support multiple conclusions
Concept
Evaluation: Deductive vs Inductive Arguments
All arguments fall into one of two categories: deductive
arguments and inductive arguments.
Deductive arguments: where the conclusion follows
with certainty.
In a good deductive argument it is impossible for the
conclusion to be false supposing the premises are true
(whether they are actually true in reality is irrelevant to
validity).
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Concept
Evaluation: Deductive vs Inductive Arguments
All arguments fall into one of two categories: deductive
arguments and inductive arguments.
Inductive arguments: Arguments where the conclusion
probably follows from the premises. In a good inductive
argument it is improbable that the conclusion is false, if
the premises are true.
Inductive arguments are judged by the probability of
their conclusions being true (supposing their premises
are true).
Concept
Evaluation: Deductive
Arguments
Once we’ve determined the structure of an argument & whether
it is intended to be a deductive or inductive argument we can
start to determine if the argument is any good. Here are the
terms we will be using for evaluation of deductive arguments:
Valid – the premises support the conclusion
Invalid—the premises do not support the conclusion
Sound—valid, with true premises
Unsound—either invalid or valid, with false premises
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Valid vs. Sound Arguments
All men are mortal
Socrates is a man
Therefore, Socrates is mortal
1. All S are P.
2. All M are S
Therefore: All M are P.
Standard Form Categorical Syllogism
1. All persons who are men (S) are persons who are mortal (p)
2. All persons identical to Socrates (m) are persons who are men (S)
Therfore, All persons identical to Socrates are persons who are mortal
(When arguments are translated into the standard form for a categorical
syllogism they sometimes look a little awkward)
Concept
Evaluation: Valid vs. Sound Arguments
Arguments can still be valid even if the
reasons are not actually true.
• An argument’s validity depends only on the
support the reasons give to the conclusion.
This means you do not even need to know
if the reasons are true or false to refute
some arguments.
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Sound
Valid
Deductive
Arguments
Unsound
Invalid
(all are unsound)
Concept
Evaluation: refuting bad arguments
Refutation: The act of showing some claim or
argument to be false.
Can be accomplished either by…
1. Attacking the inference
•
Show the that the reasons, even if true do not
support accepting the conclusion (i.e. Invalid)
2. Attack the premises
•
Show one or more of the premises to be false,
misleading or inaccurate (i.e. Unsound).
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Concept
Evaluation: refuting bad arguments
Attacking the Inference:
Two “simple” methods of proving Invalidity
1. The Counter-Example method
2. Identify fallacies
Concept
Evaluation: refuting bad arguments
The Counter Example Method:
1. Isolate the arguments form by substituting letters
for the terms contained in the premises.
2. While keeping the form of the argument intact
substitute new terms for the old ones– (this is
called a “substitution instance”)
3. See if you can construct a substitution instance
with true premises but a false conclusion. If you
can, the form of the argument is invalid.
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Example #1
If I get the flu then I will experience cough, fever
and chills
I am experiencing cough, fever and chills
Therefore I have the flu
Example #1
If [I get the flu] then [I will experience cough,
fever and chills]
[I am experiencing cough, fever and chills]
Therefore [I have the flu]
If p then q.
q.
Therefore, p
p = Its Monday
q = The Banks are Open
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Example #1
If it’s Monday then the banks will be open
The Banks are open
Therefore it’s Monday
If p then q.
q.
Therefore, p
p = Its Monday
q = The Banks are Open
Mistake: “Affirming the Consequent”
Valid Form
(Affirming the Antecedent)
If I get the flu then I will
experience cough, fever and
chills
I am experiencing cough, fever
and chills
Therefore I have the flu
If p then q.
q.
Therefore, p.
If I get the flu then I will
experience cough, fever and
chills
I have the flu
Therefore I am experiencing
cough fever and chills
If p then q.
p.
Therefore, q.
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Example #2
If acupuncture was a dangerous procedure then
it would be foolish to try it
Acupuncture is not a dangerous procedure
Therefore it is not foolish to try it
Example #2
If [acupuncture was a dangerous procedure]
then [it would be foolish to try it]
[Acupuncture] is not [a dangerous procedure]
Therefore [it is not foolish to try it]
If p then q.
Not-p.
Therefore, not -q
p = It’s a cat
q = It’s furry
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Example #2
If It’s a cat then its furry
It is not a cat
Therefore it is not furry
If p then q.
Not-p.
Therefore, not -q
p = It’s a cat
q = It’s furry
Mistake: “Denying the Antecedent”
Valid Form
(Denying the consequent)
If acupuncture was a
dangerous procedure then
it would be foolish to try it
Acupuncture is not a
dangerous procedure
Therefore it is not foolish to try
it
If p then q.
Not-p.
Therefore, not -q
If acupuncture was a
dangerous procedure then
it would be foolish to try it
It is not foolish to try it
Therefore acupuncture is not a
dangerous procedure.
If p then q.
Not-q.
Therefore, not-p.
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Concept
Evaluation: refuting bad arguments
Attacking the Inference:
Two “simple” methods of proving Invalidity
1. The Counter-Example method
2. Identify fallacies
Fallacies are common errors in reasoning. These invalid
arguments are easy to spot with some training but often
appear valid to the casual observer.
Formal vs Informal Fallacies
• All the examples we just reviewed are Formal
Fallacies- the mistake can be detected just by
looking at its form
• With Informal Fallacies we must look beyond
the form to the actual content of the
argument in order to detect the mistake in
reasoning.
• The following are all cases of informal
fallacies…
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Post Hoc Fallacy
• Post hoc ergo propter hoc
– “after this, therefore
because of this”
•
Example: “More and more young
people are attending high schools
and colleges today than ever
before. Yet there is more juvenile
delinquency and more alienation
among the young. This makes it
clear that these young people are
being corrupted by their
education.”
• When we assume that
because event Y followed
after event X, event X was
the cause of event Y .
• “Correlation does not
(necessarily) equal
causation”
Appeal To Ignorance
• An appeal to ignorance is
an argument for or
against a proposition on
the basis of a lack of
evidence against or for it.
If there is positive
evidence for the
conclusion, then of
course we have other
reasons for accepting it,
but a lack of evidence by
itself is no evidence
• There is no evidence
against p. Therefore, p.
• There is no evidence for
p. Therefore, not-p.
• “Absence of evidence is
not evidence of
Absence…”
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Examples Appeal To Ignorance
Atheist
• “A god cannot possibly
exist—there is simply no
evidence to suggest such a
being is or ever has been
active in the world”
Theist
• “Atheists have strived in
vein to kill god, but Science
cant disprove God…God is
real”
Begging The Question
• Any form of argument in which the conclusion
occurs as one of the premises, or a chain of
arguments in which the final conclusion is a
premises of one of the earlier propositions in
the chain.
– More generally, an argument begs the question
when it assumes any controversial point not
conceded by the other side.
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Begging the Question = Circular Reasoning
“Chocolate Ice cream is my
favorite because I think it’s the
best!”
“The Governor must be innocent,
because he would never do such
a thing.”
“Society has an obligation to
support the needy because those
who cannot provide for
themselves have a right to the
resources of the community”
Because it
is the word
of God
God exists
Why
should we
trust the
Bible?
How do
you know?
The Bible
Says He
does
Straw Man
• The Straw Man fallacy is
committed when a
person simply ignores a
person's actual position
and substitutes a
distorted, exaggerated
or misrepresented
version of that position.
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Straw Man Examples
• “Environmentalists care more for snail darters
and spotted owls than they do for people”
• “So called Pro-life people are really anti-woman.
They don’t think women should have rights, after
all they are just be baby-making factories.”
• “My opponent prefers raising taxes to cutting
unnecessary spending”
• “Those people that want to teach our kids about
sex and condoms in schools think its just fine if
our children are promiscuous”
Complex Question
• Two or more questions
are asked in the guise of
a single question
expecting a single
answer given to both of
them. The person
questioned is led or
trapped into affirming a
false conclusion simply
by answering the
question.
Have you stopped
plagiarizing your papers?
Is President Bush lying
about 9/11 again?
Why is Barack Obama
afraid of people seeing his
birth certificate?
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Complex Question
Leading Question
“Tell us, on the night of April
9th did you see the defendant
shoot the deceased?”
Straightforward Question
“What did you see on the night
of April 9th?”
Red Herring
• Arguer diverts the
attention of the audience
away from the subject to
a different (sometimes
related) subject. They
either finish by drawing a
conclusion from this
different issue or by
merely pretending the
original conclusion has
been established.
“Environmentalists complain
about the dangers of
nuclear power but
unfortunately electricity is
dangerous no matter where
it comes from. Every year
hundreds of people are
electrocuted by accident.”
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False Dichotomy/Dilemma Fallacy
• The fallacy of false dichotomy is committed when the
arguer claims that his conclusion is one of only two
options, when in fact there are other possibilities. The
arguer then goes on to show that the 'only other
option' is clearly outrageous, and so his preferred
conclusion must be embraced (FF).
• Example: “Either I keep smoking, or I'll get fat. I don't
want to get fat, so I better keep smoking.”(FF)
• Example: “Either your with us or your with the
terrorists”
False Compromise Fallacy
• An argument that assumes that with any debatable
topic the truth must lie somewhere in the middle—
regardless of the quality of reasoning presented for the
arguments.
• Example: “I guess the truth is somewhere in the
middle…”
• Example: “On the one side anti-tobacco crusaders
make strong claims about how dangerous tobacco is.
And the tobacco companies don’t admit that its
dangerous at all…I think the truth is probably
somewhere in between these two extremes.
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Hasty Generalization Fallacy
• To make a hasty
generalization is to
make a judgment about
a group of things on the
basis of evidence
concerning only a few
members of that group.
• Example: "I know one of
those insurance
salesmen. You can't
trust any of them."
Hasty Generalization Fallacy
• Statisticians refer to this error as the failure to
consider sample size. Accurate judgments
about a group can be made on the basis of a
sample only if the sample is sufficiently large
and every member of the group has an equal
chance to be part of the sample (Schick 140).
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Slippery Slope
• A claim that some event
must inevitably follow
from another, usually as
a chain reaction, when
there is not sufficient
reason to think that the
chain reaction will
actually take place.
“If we allow a ban on
‘partial birth’ abortion,
then soon all abortions
will become illegal.”
“If we allow a ban on
assault weapons soon
they will try to take away
our hand guns as well”
Subjective Fallacies
• Subjectivist fallacies in one way or another
dispense with objectivity and introduce bias
or prejudice.
• Subjectivist fallacies introduce bad premises
which cannot support an objective conclusion.
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Appeal to Emotion
• An appeal to emotion is a
type of argument which
attempts to arouse the
emotions of its audience in
order to gain acceptance of
its conclusion. Appeals to
emotion are always
fallacious when intended to
influence our beliefs, but
they are sometimes
reasonable when they aim
to motivate us to act (FF).
• “My opponent likes to use
every chance he gets to
drag our country’s name in
the Dirt...I question his
patriotism. I on the other
hand believe America is the
greatest country on earth.”
• “Marijuana is so dangerous,
scientists don’t even know
some of the ways in which it
might be harmful.”
Appeal to Majority/Bandwagon Fallacy
• Bandwagon arguments attempt to persuade
by appealing to a popular sentiment, such as
patriotism, loyalty, tradition, custom, etc. But
whether the group thinks something is not a
reason why something is correct.
• A proposition must be judged by evidence,
not by consensus.
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Fallacies of Credibility
• We all need to trust the word of authorities to
some degree. But in order for an authority to be
credible, they must fulfill at lest 2 conditions
1. They should have relevant expertise on the
subject in question.
2. They are reporting on what they know
objectively through reason and evidence,
without distortion or prejudice
Fallacies of credibility use authorities in a way
that violate these standards.
Ad Hominem or “against the man”
• A debater commits the Ad
Hominem Fallacy when
he introduces irrelevant
personal premises about
his opponent. Such red
herrings may successfully
distract the opponent or
the audience from the
topic of the debate.
• “Pay no attention to what
he says, he’s just a loud
mouth conservative
lunatic…”
• “You sir are a disgrace,
you should be ashamed
of yourself, I don’t know
how you sleep at night…”
• “Why should I trust what
you say about abortion,
you are a Priest, you need
to believe it’s a sin.”
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Appeal to Authority
• The fact that some
authority says
something is taken as
proof of its
truthfulness; this is to
be distinguished from
the word of an
authority lending
credibility to some
claim.
•
•
“President Richard Nixon should be
re-elected because he has a secret
plan to end the war in Southeast
Asia”
“my parents taught me that spanking
is the most effective means of
control”
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
Either we require forced
sterilization of the third world
peoples or the world
population will explode and
all of us will die. We certainly
don’t want to die, so we must
require forced sterilization.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
Either we require forced
sterilization of the third world
peoples or the world
population will explode and
all of us will die. We certainly
don’t want to die, so we must
require forced sterilization.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
The position open in the
accounting department
should be given to Frank
Thompson. Frank has six
hungry children to feed, and
his wife desperately needs an
operation to save her
eyesight.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
The position open in the
accounting department
should be given to Frank
Thompson. Frank has six
hungry children to feed, and
his wife desperately needs an
operation to save her
eyesight.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
Some of the parents in our school
district have asked that we provide
bilingual education in Spanish. This
request will have to be denied. If we did
provide this service soon people would
ask for bilingual education in Greek.
Then it will be German, French, and
Hungarian they are asking for. Soon
after we might be asked to provide
teaching in Polish, Russian, Chinese,
Korean. We simply cannot
accommodate all of them.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
Some of the parents in our school
district have asked that we provide
bilingual education in Spanish. This
request will have to be denied. If we did
provide this service soon people would
ask for bilingual education in Greek.
Then it will be German, French, and
Hungarian they are asking for. Soon
after we might be asked to provide
teaching in Polish, Russian, Chinese,
Korean. We simply cannot
accommodate all of them.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
People who lack humility have no
sense of beauty because everyone
who possess a sense of beauty is
humble.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
People who lack humility have no
sense of beauty because everyone
who possess a sense of beauty is
humble.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
Sylvia, I saw you shopping for
wine the other day.
Incidentally, are you still
drinking excessively?
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
Sylvia, I saw you shopping for
wine the other day.
Incidentally, are you still
drinking excessively?
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
We’re all familiar with the complaint
that over 40 million Americans are
without health insurance. But Americas
doctors, nurses, and hospitals are
among the best in the world.
Thousands of people come from abroad
every year to be treaded here. Clearly
there is nothing wrong with our health
care system.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
We’re all familiar with the complaint
that over 40 million Americans are
without health insurance. But Americas
doctors, nurses, and hospitals are
among the best in the world.
Thousands of people come from abroad
every year to be treaded here. Clearly
there is nothing wrong with our health
care system.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
On Friday I took Virginia out to dinner.
She told me that if I wasn’t interested in
a serious relationship, I should forget
about dating her. On Saturday I took
Margie to a film. When we discussed it
afterward over a drink, she couldn’t
understand why I wasn’t interested in
babies. Women are all alike. All they
want is a secure marriage.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
On Friday I took Virginia out to dinner.
She told me that if I wasn’t interested in
a serious relationship, I should forget
about dating her. On Saturday I took
Margie to a film. When we discussed it
afterward over a drink, she couldn’t
understand why I wasn’t interested in
babies. Women are all alike. All they
want is a secure marriage.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
After reading “Homosexuals in the
Churches” I’d like to point out that I
don’t know any serious, capable
exegetes who stumble over Saint Paul’s
denunciation of homosexuality. Only a
fool can fail to understand the plain
words of Romans 1 that homosexuals
become that way because of their own
lusts.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
After reading “Homosexuals in the
Churches” I’d like to point out that I
don’t know any serious, capable
exegetes who stumble over Saint Paul’s
denunciation of homosexuality. Only a
fool can fail to understand the plain
words of Romans 1 that homosexuals
become that way because of their own
lusts.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
The death penalty is the punishment
for murder. Just as we have long jail
terms for armed robbery, assault and
battery, fraud, etc. and fines for
speeding or traffic violations, so we
must have a punishment for murder.
Yes the death penalty will not deter
murders any more than a speeding
ticket will deter violating speed laws,
but it is the punishment for such
violation!
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
The death penalty is the punishment
for murder. Just as we have long jail
terms for armed robbery, assault and
battery, fraud, etc. and fines for
speeding or traffic violations, so we
must have a punishment for murder.
Yes the death penalty will not deter
murders any more than a speeding
ticket will deter violating speed laws,
but it is the punishment for such
violation!
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
If the advocates of prayers in public
schools win on this issue, just where will
it end? Perhaps next they will ask for
prayers on public transportation?
Prayers by government workers before
they start their job each day? Or maybe
mandatory prayers in public restaurants
before starting each mean might be a
good deal.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
If the advocates of prayers in public
schools win on this issue, just where will
it end? Perhaps next they will ask for
prayers on public transportation?
Prayers by government workers before
they start their job each day? Or maybe
mandatory prayers in public restaurants
before starting each mean might be a
good deal.
Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
As corporate farms continue to gobble
up smaller family farms, they control a
larger percentage of the grain and
produce raised in the US. Some have
already reached a point in size where, if
they should decide to withhold their
grain and produce from the
marketplace, spot shortages could
occur and higher prices would result.
The choice is to pay us family farmers
now or pay the corporations later.
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Name The Fallacy
Appeal to Authority
Ad Hominem
Appeal to ignorance
Begging the Question
Straw Man
Post Hoc Fallacy
Hasty Generalization
False Dichotomy
Slippery Slope
Appeal to Emotion
Bandwagon
Red Herring
Complex Question
As corporate farms continue to gobble
up smaller family farms, they control a
larger percentage of the grain and
produce raised in the US. Some have
already reached a point in size where, if
they should decide to withhold their
grain and produce from the
marketplace, spot shortages could
occur and higher prices would result.
The choice is to pay us family farmers
now or pay the corporations later.
Concept
Evaluation: Inductive Arguments
But what if we cant prove our conclusion is 100% certain, based
on our premises?
Is our argument, necessarily a bad one?
Arguments that provide us less-than-certain conclusions are
called inductive arguments.
Inductive arguments are judged by the probability of their
conclusions being true (supposing their premises are true).
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Concept
Evaluation: Inductive Arguments
Here are the terms we will be using for evaluation of Inductive
arguments:
Strong – the premises make the conclusion more likely to be true
Weak—the premises do not make the conclusion more likely true
Cogent—strong, with true premises
Uncogent—either strong or weak, with false premises
Cogent
Strong
Inductive
Arguments
Uncogent
Weak
(all are uncogent)
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Does the strength of the inference increase or
decrease?
Increase
Decrease
No impact
Strong
Weak
Cogent
Uncogent
Jessica has long admired
Rachel’s near-perfect body,
and she notes that Rachel
works out on a Roboflex
exercise machine. Jessica
concludes that if she buys a
Roboflex for herself she will
be able to duplicate Rachel’s
results.
Does the strength of the inference increase or
decrease?
Increase
Decrease
No impact
Strong
Weak
Cogent
Uncogent
Jessica has long admired
Rachel’s near-perfect body,
and she notes that Rachel
works out on a Roboflex
exercise machine. Jessica
concludes that if she buys a
Roboflex for herself she will
be able to duplicate Rachel’s
results.
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Bayes Theorem
Bayes Theorem
The probability
our idea is true
How typical our
explanation is
X
{ TheRepeat
above }
+
How likely the evidence
is if our idea is true
=
How atypical our
explanation is
X
How likely the evidence
if our idea is not true
}
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Concept
Evaluation: Inductive Arguments
There are many different kinds of Inductive arguments, here are
a few:
Prediction- an argument that proceeds from our knowledge of the past to a
claim about the future
Argument from analogy – an analogy is drawn between a well known or
uncontroversial case (X) and a lesser known case or controversial case (Y). If
the two cases are similar enough, then a feature that is true of X may also be
true of y.
Generalization – proceeds from knowledge of a selected sample to a general
claim about the whole group.
Causal Inference – an argument that proceeds from the knowledge of a cause
to a claim about an effect or vice versa.
What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
Paying off terrorists in
exchange for hostages is not
a wise policy, since such
action will only lead them to
take more hostages in the
future.
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What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
Paying off terrorists in
exchange for hostages is not
a wise policy, since such
action will only lead them to
take more hostages in the
future.
What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
Eddie has lost at the craps
table for the last ten throws
of the dice. Therefore, it is
extremely likely that he will
win on the next throw.
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What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
Eddie has lost at the craps
table for the last ten throws
of the dice. Therefore, it is
extremely likely that he will
win on the next throw.
What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
Airline passages must go through
a metal detector and/or pat down
to make sure they do not bring
any dangerous weapons on
board. Similarly concert venues
should use the same procedures
to prevent alcohol and drugs from
being carried into rock concerts.
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What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
Airline passages must go through
a metal detector and/or pat down
to make sure they do not bring
any dangerous weapons on
board. Similarly concert venues
should use the same procedures
to prevent alcohol and drugs from
being carried into rock concerts.
What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
So far every cat that has been
tested for self-knowledge in the
laboratory has failed to recognize
itself (as itself) in the mirror. It is
likely that no cats have the ability
for self-knowledge.
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What kind of Inductive Argument is this?
Prediction
Analogy
Generalization
Causal Inference
Strong
Weak
Cogent
Uncogent
So far every cat that has been
tested for self-knowledge in the
laboratory has failed to recognize
itself (as itself) in the mirror. It is
likely that no cats have the ability
for self-knowledge.
Concept
3 Quick Standards for Judging Validity/Cogency
Bulletproof:
Deductive Validity: Can you think of any way the reason(s) could be true and the
conclusion false (however unlikely)?
Very Strong:
Proved Beyond a Reasonable Doubt: If the reasons are true (or otherwise
acceptable) would a rational person have any real doubt about whether the
conclusion is true (or otherwise acceptable?)”
Acceptable:
Shown to be more likely than not On the Balance of Evidence: If the reasons
are true, is the probability of the conclusion being true more likely than it not
being true (given all available evidence)?
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