Transcript Logic Slides 3 - Mount St. Mary's University

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Logic Slides 3
Fallacies
PHIL 211
Cosmos to Citizen
Dr. Mike Miller
Mount St. Mary’s College
List of Fallacies
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Any argument that makes a mistake in reasoning is fallacious (that is, commits a
fallacy). There are many fallacies. We have already looked at a number of
fallacies, including the fallacies of:
Ad hominium Confusing the worth of an argument with the person making the
argument.
Equivocation When two clear but different meanings exist in the same sentence.
False Cause Either looking too hard for a cause, overlooking a common cause,
or reversing cause and effect.
Hasty Generalization Either too small a sample, a non-representative sample, or
a biased survey.
Loaded Language Including euphemisms, dysphemisms, up-players, downplayers and weasel words.
The following slides provide just some of the more popular fallacies. Many are
covered in Weston, Chapter X. Others presented here are not in Weston.
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An argument commits the Appeal to Ignorance (ad ignorantiam) when it argues
that a proposition should be believed until it proven false. For example, . . .
No one has ever proven that the Loch Ness
Monster does not exist. Therefore, we must
conclude that Nessie exists.
No, all that can be concluded from nothing is
nothing. Don’t conclude more than you can.
Both of the following arguments are equally bad. Do you understand why?
Atheist: God can’t exist
because there is no evidence
to prove he does.
Believer: God must exist
because no one has ever
proven that he doesn’t.
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Someone commits the Appeal to Emotion fallacy when they use emotion alone
to ‘prove’ their point, and not reason. Don’t get me wrong – emotion has a
place in our deliberations. But the use of emotion without argumentation is
wrong because emotion alone is a lousy reason for believing any claim.
It is important to note that the use of emotion in an argument is wrong only if:
• The appeal to emotion is the only claim supporting the conclusion
• The appeal to emotion isn’t enough to justify the conclusion
Any emotion can be used in this fallacy. Here are a couple of common
variations of the appeal to emotion fallacy . . .
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An argument is called an Appeal to Pity if it says, roughly:
You should believe or do _____ if you feel sorry for _____.
You should give me an A because I really need to
have a high GPA so I can get into a good law
school. If I don’t, I think my mother will die.
An argument is called an Appeal to Fear if it says, roughly:
You should believe or do _____ if you are afraid of _____.
Vote for Anthony for class president. Oh, by the way, did you
know his older brother – the 2 time state boxing champ – is very
interested in the outcome of the election? Think about it.
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An argument is called an Appeal to Spite if it says, roughly:
You should believe or do ____ if you are mad about what ____ has done or believes.
Co-worker: You can’t agree to take over Billy’s
responsibilities when he goes on vacation next
week! Don’t forget, he told everyone that he
didn’t like your haircut.
Appeals to emotion are fallacies. But don’t forget, not every argument that
includes a reference to an emotion is a bad argument. Can you think of an
example of an argument that includes emotion, but is not an appeal to emotion?
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An argument is an Ad Populum fallacy when it argues that since everyone else
does something (or believes something), then it is OK to do it (or believe it).
It is never a good idea to just follow the crowd without a good reason. Be a
leader, or if you follow – do so for a reason. What do you think of the
following?
Well, since everyone at
school is sniffing glue, I’m
going to do it too!
Don’t be an idiot! If
everyone was jumping
of the Brooklyn
Bridge . . .
Since just about every great thinker in the past thought that
women were not as valuable as men, men must be better.
Don’t believe it. Everyone (even great thinkers) can be wrong!
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Do you remember the deductive forms of modus ponens and modus tollens?
Both of these forms are valid (that is, the premises really do support the
conclusion, assuming the premises are true). However, some arguments that
have a similar form (that is, rely on a sentence with the form ‘if P, then Q’ or ‘if
antecedent, then consequent’) are invalid. One such fallacious argument is
called Affirming the Consequent. It looks like this:
If P (antecedent), then Q (consequent) If it is raining, the street gets wet.
Q (affirming the consequent)
The street is wet.
Therefore, P
Therefore, it is raining.
This argument form is always invalid (the premises don’t support the conclusion,
even if they are true). Why? Well look at the example above. It doesn’t mean
that it is raining just because the street is wet. A fire hydrant may have been left
on. Some kids may have had a massive water balloon fight. Or, the dam could
have sprung a leak. Any number of things other than a rain storm could account
for why the street is wet so the conclusion doesn’t have to be true.
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A similar fallacy is called Denying the Antecedent. Here is the form and an
example:
If P, then Q
If George hits a home run, then we will win the game.
Not-P
George didn’t hit a home run.
Therefore, not Q Therefore, we didn’t win the game.
Fine. Let’s imagine the two premises are true. The conclusion, however, does not
necessarily follow because it is possible that we can win the game in other ways
than George hitting a home run. Maybe he strikes out, but another hitter scores the
game winning run. Since the premises of this argument could be true, but the
conclusion false we know that the argument is invalid – as is every argument that
commits the fallacy of Denying the Antecedent.
Can you identify the fallacies committed in the following arguments?
If I am not happy, then it is Monday. It
is Monday. Therefore, I am not happy.
If I am not hungry, then it is late. I
am hungry. Therefore, it is not late.
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Begging the Question (or circular reasoning) occurs when someone implicitly
uses their conclusion as a premise. In doing so the conclusion has no support.
Just as it is impossible to pull yourself up by your bootstraps, so too you can’t
successfully prove a conclusion by assuming the conclusion is true. This
fallacy is called ‘begging the question’ because the answer to the question
being asked is given before any reasoning is offered.
For example . . .
Frankie is telling the truth because he never lies.
Sleeping pills makes you sleepy because they put you to sleep.
I believe in God. Why? Because the Bible says God exists.
Do you understand why each of these arguments is ‘begging the question’?
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A Complex Question is a question that conceals a dubious claim that should
be argued for rather than assumed. Complex questions try to trap the
respondent into admitting something they might not want to admit, or to agree
with a conclusion that is not supported by any evidence. For example, . . .
When did you stop beating your wife?
When are you going to do something worthwhile
with your life?
Where did you hide the cookies you stole?
The best way to “escape” a loaded question is to directly address the
concealed claim, rather than answer the question as it is asked.
How would you ‘escape’ the complex questions above?
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A False Dilemma is an argument that uses an “or” claim that appears to be true
but isn’t, because another possibility exists that is purposely left hidden. Similar
to a complex question, the person who uses a false dilemma is trying to trap
someone else. But this time, he or she is trying to trap you into a particular
action or belief.
Husband to wife: Either you will buy me Hummer or
you hate my guts. Since you don’t hate me, you must
buy me a Hummer.
False dilemmas try to force you into a corner. To “get out” of a false dilemma,
simply point out that other possibilities exist.
Dad: You are either going to go to college or be a bum for the rest of
your life.
Son: I will not go to college.
Dad: Then you will be a bum for the rest of your life.
What is the way out?
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You can’t prove anything without giving an argument, even if you claim that
you have done so. If you attempt to do so, you have committed a Proof
Substitute. A proof substitute is a word or a phrase that suggests there is proof,
but no proof is actually offered.
That is, you don’t prove anything when you try to browbeat others into
accepting your argument by using phrases such as “it is obvious that . . .”,
“clearly . . .” or “surely, anyone of intelligence will agree that . . ..” You
win arguments by giving reasons, not by making it appear as if you have
reasons. For example, . . .
It is certain that dogs are better pets than cats.
Without a doubt Michael Jordan is the best basketball player ever.
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A person commits the Red Herring fallacy when they try to divert the attention
away from the topic being discussed to a different –and often controversial – topic.
It is hoped that the new topic will be so interesting that the first topic will never be
taken up again. For instance, in the following argument notice how Senator Smith
tries to steer the conversation away from the issue the reporter wants to discuss. . .
Reporter: Senator, why did you accept a $20,000 dollar donation to your
campaign from John Jones, a convicted felon?
Senator Smith: Well, John Jones is a citizen of Arizona, who is deeply
troubled by those in his state that want to make Spanish an official state
language. I love all Americans, including those hard-working people
who came to America from Mexico. But I believe all immigrants must
become true Americans. That means they must learn to speak English.
We must provide education for all people, so that everyone – rich or poor
– have the ability to speak and read English, so as to become productive
members of society.
The Senator is hoping that the reporter (and others who are listening) will forget the
scandalous issue and focus instead on his controversial comments about immigration.
If they do, he’s pulled off a red herring.
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Ridicule is bad because it doesn’t give a reason why an argument is wrong. It
instead tries to belittle the creator of the argument. Although it may end the
argument, it makes a lot of enemies.
What? You think that it follows that men
should wear dresses from what you said.
The only thing that follows from what you
said is that you are an idiot! Ha! Ha!
Note: Since Ridicule (which is illegitimate) and reducing to the absurd (which is
legitimate) are somewhat similar, if one does not make it clear that they are
reducing an argument to the absurd it is best to consider the refutation to be ridicule.
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Although hypothetical syllogisms are a valid deductive form, when one of the
conditionals is false (or even dubious) the hypothetical syllogism may end up
committing the Slippery Slope fallacy. For instance . . .
If you drop philosophy you won’t have enough credits to
graduate. If you don’t graduate, you will never get a good job.
And without a good job your life will be miserable. Therefore,
you will end up living on the street, drunk and lonely.
What’s wrong with this example? It’s valid, right? It is a fallacious argument
because at least one of its conditionals is dubious. That is, what about summer
school? Is it really true that if you don’t graduate from college you will never get
a good job? Or that without a good job your life will be miserable? Or that
misery leads to being a drunk?
The danger with a slippery slope argument is that if you fail to reject the dubious or
false premise, you might end up ‘sliding’ all the way to a faulty conclusion.
Can you make an argument that commits the slippery slope fallacy?
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When one person makes a claim and a second person does not address that claim
directly but attacks a misrepresentation of what the first person said (or even
what the first person did not say at all), and suggests that they have defeated the
claim made by the first person, they have given a Straw Man fallacy. Consider
this following exchange in a debate . . .
Candidate Jones: I think we should use any surplus tax revenue
to pay down the national debt.
Candidate Smith: Obviously my opponent doesn’t care about
protecting Social Security and all of our nation’s senior citizens.
These people deserve our protection. To abandon them to
poverty as she suggests is wrong. Obviously, any surplus tax
revenue should not be used to pay down the national debt.
Did you notice how Smith ‘twisted’ Jones’ statement into something else, ‘defeated’ the
new statement, and then claimed victory over Jones’ initial statement? This fallacy is
very successful if the listening audience is not paying attention . . .. So stay awake!
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Although red herring and straw man fallacies are somewhat similar (both use
misdirection) they should not be confused. Those committing a red herring
fallacy want to pull their listening audience to a new topic – and never return to
it! They hope you don’t notice the switch, so they don’t have to discuss the
initial point.
However, those committing the straw man fallacy do return to the initial topic,
but only after they have ‘defeated’ a different (and often weaker) version of
what someone said. They hope you don’t notice the switch and will think that
they did indeed defeat the first claim.
By the way, why do you think these two fallacies have the names that they do?
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Please contact me with any questions about the
information in these slides or the related assigned reading:
• Weston, Chapter X
• Logic Handout, p. 6-14.