November Week 4
Course Week 12: “Appeal to Ignorance”
(Suggested use: November 26-November 30)
Monday
Please turn to a fresh page in your Logic notebook and copy the following statements:
1.
“You should buy me lunch. I can’t find a bit of evidence that says you shouldn’t.”
2.
“This curriculum is the best. Nothing has been proven to be better.”
3.
“He isn’t qualified! You haven’t proven that he is.”
Each of these examples uses the same type of bad reasoning. Based on your experience and
background knowledge, try to find the faulty logic in each example. What do you notice about the
evidence or justification (or the lack of evidence or justification) presented in each example? What
just doesn’t sound right to you?
Jot down a few notes about the bad reasoning you think these examples have in common. Don’t
worry if you’re not sure! Just study each example and look for reasoning that doesn’t make sense to
you. It’s a great idea to talk this over with others if you’d like. We’ll discuss the faulty reasoning
used in each of these statements in the next session.
Tuesday
• Read the explanation below of the informal fallacy used in yesterday’s examples.
In each example above, the speaker fails to back up the statement or claim with supporting reasons or
evidence. Instead, the speaker just says that the statement is true because it hasn’t been proven false,
or that it’s false because it hasn’t been proven true. Nonsense! This is bad reasoning at its worst. Lack
of evidence against your point doesn’t make your point true. In order to make a logically sound
argument, a statement or claim must be backed up by evidence that supports it.
The statements above, with their lack of evidence, are examples of the Appeal to Ignorance fallacy.
The Latin term for Appeal to Ignorance is Argumentum ad Ignorantiam. That has a certain ring to it,
don’t you think? In this case, ignorance means “lack of evidence to the contrary.” We’ve been talking
all this semester about supporting a statement with evidence; the Appeal to Ignorance fallacy is
another type of bad reasoning where the evidence is missing in action.
•
At the top of the notebook page on which you wrote the examples on Monday, please
write the title Appeal to Ignorance.
•
Under the examples you copied yesterday, write the definition of Appeal to Ignorance
in your own words.
•
Read the following examples. Jot down the letter of each example that you believe
contains the informal fallacy Appeal to Ignorance.
a. “Elect Mr. Boss. There’s no reason not to.”
b.
“Homeschooling is bad for children. It hasn’t been proven to be good.”
c.
“Exercise is important to health. The Millionaires Association says so.”
d.
“Joje track shoes are best! Nothing has been shown to be better!”
•
Double-check your conclusions with the answers below. Then copy those examples
that contain the week’s fallacy into your notebook.
Answers for Tuesday
Tuesday’s examples that contain the informal fallacy Appeal to Ignorance: a, b, and d. Note that
example b is untrue as well as an Appeal to Ignorance. Example c is an Appeal to Faulty Authority.
Exercise is important to health, but the Millionaires Association is not recognized as an authority on
either health or exercise.
Wednesday
It’s time to find your own examples of this week’s informal fallacy, Appeal to Ignorance, and record
them in your notebook.
Thursday
It’s quiz day! Some of the examples below contain the informal fallacy Appeal to Ignorance. Others
may be examples of other informal fallacies we’ve covered, or may not include an informal fallacy.
Please read each example and note which, if any, of the informal fallacies we’ve covered is contained
in each. Then check your responses with the answers that appear below the quiz.
1.
“You should definitely buy this certificate giving you part ownership of
the Brooklyn Bridge. All of your neighbors have bought them today!”
2.
“You can’t make us pay rent! Terrible things will happen if you do!”
3.
“SuperDuper Shakes are not healthy! No studies have been done to
prove that they are.”
4.
“Can I please go to the game, Dad? Mr. Brilliant lets his kids go. He says
it’s good for kids to go to the game. The Brilliants won the Spelling Bee, the
Geography Bee, and National Family Choral Competition the last five years in
a row. They’re the best at everything! Since Mr. Brilliant lets his kids go, you’ll
let me go, right Dad?
5.
“Wipety Wipes are the best on the market! No wipe has ever proven to
be better!”
6.
Wife: I’m really not sure you should purchase another antique fire
engine, darling. We have forty-three already, and we’re beginning to run out of
garage space!
Husband: You don’t understand how important it is to have hobbies and
interests!
7.
“I would never buy anything from his store. His children begged him for
a swimming pool and he refused to put one in! He’s a terrible father!”
8.
“You’re telling me not to eat fast food? I saw you pulling out of the Big
Ol’ Burgers drive-through yesterday!”
9.
“We can’t support the school nutrition bill he’s proposed! It’s a bad bill.
It’s never been shown to be any good.”
10.
“Why should you vote in favor of the school nutrition bill? I’ll tell you
why. My neighbors haven’t been to a decent restaurant in six months! They
always go to the same sandwich shop, and they think that’s a nice dinner. I take
my wife and kids to The Fancy Family every week and let them get whatever
they want. It’s good, it’s cheap, and everyone likes it. It’s much better than that
little Measly Muffins on the corner. We never go there.”
Answers to Logic Quiz – Week 12
The following examples employ the informal fallacy Appeal to Ignorance: 3, 5, 9. Instead of giving
evidence, reasons, or facts to support the claims in these statements, the writer or speaker tells us that
there isn’t evidence against his statement or claim.
Example 1 demonstrates the Appeal to the People fallacy. According to this bad reasoning, everybody
(or practically everybody) else is doing it, so shouldn’t you?
Example 2 is the informal fallacy Appeal to Fear. Yikes! Terrible things will happen if you don’t!
Number 4 is an example of the Appeal to Faulty Authority fallacy. Mr. Brilliant may be the expert on
raising his own kids, but that doesn’t mean he is an authority on raising this dad’s kid.
Number 6 is a Straw Man fallacy. Husband sets up his wife’s argument as a position against all
hobbies and interests, which is not what she was saying. Having no hobbies or interests is a position
that’s easy to argue against, which husband then does. He should, instead, deal with the issue his wife
actually raised—the fact that they already have forty-three fire engines and are beginning to run out
of garage space.
In example 7, instead of giving any legitimate reasons why the speaker won’t shop at this store, we’re
just told that the owner is a bad father. Clearly, this is an attack against the person, a classic Ad
Hominem fallacy.
Statement 8 is an example of the Tu Quoque fallacy. The fact that someone else may have purchased
and consumed fast food really has no bearing on whether it is a good idea for another person to
indulge.
In number 10, the story about eating out has absolutely nothing to do with whether the school
nutrition bill is worthy of our support. It just distracts us from the point we should be considering, and
is a classic Red Herring.