Transcript Fallacies 1 - Michael Johnson's Homepage

Fallacies 1
ARGUMENTS
One of our main critical thinking questions was:
Does the evidence support the conclusion?
How do we evaluate whether specific evidence
supports a specific conclusion? How do we
answer this question?
Arguments
The word ‘argument’ as it is
used normally in English,
means something like this:
“An exchange of diverging or
opposite views, typically a
heated or angry one: ‘I've
had an argument with my
father’.”
Arguments
In philosophy, we use the word ‘argument’
differently. A philosophical argument:
• Is not an exchange of views
• Doesn’t need to present opposing or contrary
views
• Is not typically heated or angry.
Arguments
Instead, a philosophical argument consists of
two parts: the premises and the conclusion.
The premises are statements of the evidence
that are given in support of the conclusion.
The conclusion is the claim that the premises
are supposed to support.
Example
Premise 1: Either the butler is the murderer, or
the gardener is the murderer.
Premise 2: The butler is not the murderer.
Therefore,
Conclusion: The gardener is the murderer.
Relevance
There is no requirement that the premises of an
argument have anything to do with the
consequent. For example, this is an argument:
Premise: There are exactly 117 hairs on my
hand.
Conclusion: It’s half past three o’clock.
FALLACIES
Misleading Arguments
An argument is misleading when the person
making it:
• Knowingly presents unreliable evidence; or
• Knowingly presents irrelevant evidence
designed to trick you; or
• Knowingly hides relevant evidence that goes
against their claim.
Misleading Arguments
(The person making a misleading argument
doesn’t always have to do bad things knowingly.
Sometimes it is enough that they should have
known not to do those things.)
Critical Thinking
Is there any evidence to support the claim?
Is the evidence reliable and trustworthy? How
reliable is it? Should you accept it?
Does the evidence actually support the claim?
Is there other evidence you should consider?
Critical Thinking
Critical thinking involves asking these questions
at the right times, knowing how to answer
them, and knowing how to use those answers to
accept or reject a claim.
Determining If Something Is
Misleading
Is there any evidence to support the claim?
No  The claim is unsupported, but not
misleading.
Yes  Go investigate the evidence!
No (Unsupported)
Many of our beliefs are opinions that are not
supported by any evidence.
These beliefs might be wrong and we might
disagree. But as long as the person presenting
them is clear that they have no evidence and are
simply stating an opinion, this is not misleading
anyone.
No (Unsupported)
Be careful! Sometimes people’s opinions are
stated in a way that suggests there is evidence
when there really is not.
“Dr.” suggests the opinion of an expert.
“Author of [book on the subject]” suggests the
opinion of an expert.
Yes, There Is Evidence Presented
Is the evidence reliable and trustworthy?
No  Unreliable and untrustworthy evidence
can be misleading.
Yes  Keep critically thinking!
No, The Evidence Is Not Reliable
Reasons evidence might not be reliable:
•
•
•
•
It’s made up (lies).
It’s just an opinion.
It’s based on false authority.
It’s misinterpreted.
Lies
From “Ancient Aliens”:
http://www.youtube.com/watch?v=lIkbvNcl58U
Lying for What You Think Is Good
“What harm would it do, if
a man told a good strong
lie for the sake of the
good and for the Christian
church ... a lie out of
necessity, a useful lie, a
helpful lie, such lies would
not be against God, he
would accept them.”
Lying for Profit
In 1998, Dr. Andrew Wakefield published a
paper linking vaccines to a new bowel disease
which caused autism.
Later it was discovered that Wakefield faked the
results of his experiments.
He thought that if he could show a connection,
he could get $43 million USD ($333 million HKD)
from selling tests for the made-up disease.
Mere Opinions
Sometimes the premise strongly supports the
conclusion, but the premise is just someone’s
opinion.
Appeal to Authority
It’s OK to find out what to believe from experts
in many cases. However, this is not true when:
• The expert is not an expert about what you
want to know.
• Experts in general disagree about the
question.
• The expert has a history of lying or misleading
about the question.
Expert #1: Dr. Algund Eenboom
Dr. Algund Eenboom is a
doctor. A doctor of
dentistry. He is not a
scientist or a historian.
Google Search
http://www-user.rhrk.unikl.de/~aws/seta/Eenboom.h
tm
Dr. Algund Eeenboom (Leer,
Deutschland) geb. 1946 in
Leer (Deutschland) studierte
Zahnmedizin an der
Universitat Munster und
promovierte in diesem Fach
an der Universitat Tubingen.
Als Zahnarzt ist er seit 1979
in eigner Praxis tatig.
Google Translate: German to English
Dr. Lagundo Eeenboom
(Leer, Germany) born
1946 in Leer (Germany)
studied dentistry at the
University Munster and a
PhD in the subject at the
University Tubingen. As a
dentist he is TTIG since
1979 in his own practice.
Misinterpretation
Misinterpretation
Yes, Let’s Keep Thinking Critically
Does the evidence (supposing that it’s true)
actually support the claim?
No  Irrelevant evidence usually is misleading.
Yes  Keep critically thinking!
Irrelevant Evidence
There are many ways that evidence can seem to
support a conclusion, without actually doing so:
•
•
•
•
No connection with the claim.
Circular reasoning.
Better alternative explanations.
Special circumstances.
No Connection with the Claim
• Clustering illusion: it looked like there was a
pattern there, but there wasn’t.
• Regression fallacy: going back to normal
seemed to be for a reason, when it wasn’t.
• Base rate neglect fallacy: a reliable test said
the claim was true, but since the base rate of
the condition is very low, it is still unlikely that
the claim is true.
Circular Reasoning
Circular reasoning involves trying to show that a
claim is true by assuming that it is true in the
premises. It has the form:
X is true. Why? Because X.
Example:
“It says in the Bible that God exists. Since the
Bible is God's word, and God never speaks
falsely, then everything in the Bible must be
true. So, God must exist.”
Example
Premise 1: The bible is God’s word.
Premise 2: God never speaks falsely.
Conclusion: Everything in the bible is true.
Premise 1: Everything in the bible is true.
Premise 2: The bible says that it is God’s word.
Conclusion: The bible is God’s word.
Experiment
• Researchers created a list of facts that about
50% of people knew.
• Subjects in this experiment read the list of
facts and had to say which ones they knew.
• They then had to judge what percentage of
other people would know those facts.
Example
• Hong Kong has twice as many skyscrapers
(> 14 stories) as New York.
• More tourists from China come to Hong Kong
than tourists from all other countries
combined.
• Hong Kong has the highest average IQ, 107.
• Sarah Lee Wai Sze won a bronze medal at the
London summer olympics.
The Curse of Knowledge
Researchers found that the subjects responded
differently about other people’s knowledge of a
fact when the subjects themselves knew that
fact.
If the subjects did know a fact, they said that an
inaccurately large percentage of others would
know it, too. The researchers call this finding
“the curse of knowledge.”
Circular Reasoning
The researchers claim that this “curse” happens
because subjects make more mistakes when
they have to judge the knowledge of others.
People are much better at judging what they
themselves know.
Good Reasoning
The researchers claim that this “curse” happens
because subjects have trouble switching their
point of view to consider what someone else
might know, mistakenly projecting their own
knowledge onto others.
Circular Reasoning + Brains
Brain scans indicate that this “curse” happens
because of the frontal lobe brain circuitry
known to be involved in self-knowledge.
Subjects make more mistakes when they have
to judge the knowledge of others. People are
much better at judging what they themselves
know.
Straw Man Fallacy
Straw Man Fallacy
The Straw Man Fallacy (sometimes in the UK
called “Aunt Sally Fallacy”) is when you
misrepresent your opponent, and argue against
the misrepresentation, rather than against your
opponents claim.
Example: Evolution
According to the theory of evolution, any two
living things have a common ancestor.
You and I are related. We are family.
We are also related to monkeys, and rats, and
pandas.
We are also related to bugs, and bananas, and
bacteria.
Example: Evolution
http://www.youtube.com/watch?v=xO
n7DInBWK4&feature=related
Our Common Ancestor
Straw Man in Ancient Aliens
“In the Book of Ezekiel, the prophet describes a
flying chariot containing wheels within wheels
and powered by angels. Although Bible
historians suggest Ezekiel was speaking
symbolically about the terrifying enemies facing
Israel, could this be another example of an alien
visitation and proof that pre-historic aircraft
existed?”
Ezekiel’s Vision
“it expressly says in the
book that the vision is of
the glory of God on his
throne. I have read dozens
of commentaries by bible
scholars on Ezekiel and
have never found one that
said this was referring to
the enemies of Israel.” –
Chris White, Ancient
Aliens Debunked
Student Example
Straw Man: “So you’re saying there’s no possible
benefit to moral and national education in Hong
Kong?”
Real Argument: “No, I’m saying that national
education must present an accurate view of the
positives and negatives of our current situation.”
False Dilemma
An argument commits the false dilemma fallacy
when it presents two options as the only
options, even though there are actually more
options.
False Dilemma
Premise 1: We can either raise taxes on
everyone, or cut social programs.
Premise 2: Raising taxes on the poor would be
terrible, they can’t afford it.
Conclusion: We should cut social programs.
False Dichotomy in “Ancient Aliens”
“There is not a single
insect in the world which
has got its wings at the
bottom. Now, when you
exclude the possibility
that it’s an insect, one of
the things which remain is
that this thing is actually
what it looks like – yes, a
plane.”
Other Possibilities!
Puma Punku
“What nobody talks about is
the irrefutable fact that we
are at an altitude of 12,800
feet which means we are
above the natural tree line.
No trees ever grew in that
area, meaning that no trees
were cut down in order to
use wooden rollers. The
wooden roller theory falls by
the wayside.”
Straw Man Fallacy
Many in Hong Kong think
that President Benigno
Aquino of the Philippines
should apologize for the
Manila bus crisis.
Straw Man
Aquino argues:
1. No one should apologize for something that
they did not do.
2. Rolando Mendoza acted alone in taking
hostages and in killing hostages. The
Philippine government didn’t do it and the
Philippine people didn’t do it.
3. Therefore, the government/ people of the
Philippines should not apologize.
Straw Man Fallacy
A straw man argument is where you
mischaracterize your opponent’s claims or
reasons for those claims. You show that the
mischaracterization is false or misleading, and
then claim that your opponent believes false
claims or has bad reasons for her claims.
Straw Man Fallacy
Aquino is suggesting that people want him to
apologize for Mendoza’s actions.
BUT that is not what people want. They want
him to apologize for the Philippine government’s
actions: specifically, the way the crisis was
mishandled by the police.
Fallacy of the Mean
The fallacy of the mean is the assumption that a
“middle point” between two views is the right
one.
Fallacy of the Mean
Candidate 1: “We should raise taxes on
everyone”
Candidate 2: “We should cut social programs”
Therefore,
Compromise: We should raise taxes on everyone
a little and cut social programs a little.
The Fallacy of the Mean
“Lol, debunked. Not exactly. There are always
two sides to a coin and the truth usually lies in
the middle. Of course not everything on Ancient
Aliens is totally true. Of course, not everything
on this video is unbiased either.” – internet
commenter Darkeus regarding Chris White’s film
“Ancient Aliens Debunked”
Keep Thinking Critically
Is there other evidence we should consider?
This is what we talked about in the first week:
context. But it’s not always true that when we
should consider more evidence, something has
been taken out of context.
Martin Gregorie’s Tests