fallacies 2

Fallacies 2

IS THE EVIDENCE RELIABLE?

Appeal to Probability

Just because something is possible does not mean it is true.

Sample Student Homework

“‘Ancient Aliens’ is misleading because on the show they claim that alien technology was needed to move the stones for the pyramids. But people could have moved the stones in some other way.”

Appeal to Probability

1. The show says there was only one way to move the stones: aliens.

2. Maybe there were other ways to do it.3. Therefore, there were other ways to do it.4. Therefore, the show is misleading: there is

not only one way to move the stones.

Give Me Another Explanation!

You cannot prove that the show is misleading by saying maybe it is saying something false.

You have to show that it is saying something false.

Argument from Ignorance

“Absence of evidence is not evidence of absence.” – Carl Sagan

Just because there is no evidence that something is true, does not mean that it is false.

Just because there is no evidence that something is false, does not mean that it is true.

Argument from Ignorance

The argument from ignorance goes like this:

“You can’t prove that God doesn’t exist. Therefore God exists.”

It assumes that because there is no argument against a position, that that position must be correct.

Shifting the Burden of Proof

A similar fallacy is “shifting the burden of proof”. It goes:

“God exists. If you think otherwise, prove that he doesn’t!”

Here, you make a claim (“God exists”) but instead of giving evidence for it, you require that your opponent give evidence for the opposite.

“Just Asking Questions”

Frequently, conspiracy theorists will use a subtle form of the argument from ignorance:

Is X true? I don’t know. I’m just asking questions.[No arguments are presented for thinking X is not true][Audience invited to conclude that X is true.]

“Just Asking Questions”

Some people think that George W. Bush was responsible for the 9/11 terrorist attack in the US. Was he responsible? Was the US Government trying to invent a reason to attack Israel’s enemies? I don’t know. I’m just asking questions.

Argument from Incredulity

Similar to the argument from ignorance is the argument from incredulity.

This happens on “Ancient Aliens” all the time: • I can’t believe that X is true.• Therefore, X is false.

Cousins?

Ad Hominem

You cannot show that someone’s claim is false by showing that they are a bad person or that they are not an expert.

You can show that we have no reason to believe them. But to show that their claims are false we need to have evidence that their claims are false.

Erich von Däniken

• Author of Chariots of the Gods in 1968.

• One of the first to argue for ancient astronauts/ ancient aliens.

• Inspired many of the people on the show.

Erich von Däniken

• Left school at 19.• Does not have a college

degree.• Does not have a PhD.• Has never received

honors, recognition, or rewards from experts.

• Has been convicted of fraud twice.

Appeal to Motive

A version of the ad hominem fallacy is the appeal to motive. You cannot show that a claim is false by showing that the person making the claim has a strong reason to believe it or a strong reason to make you believe it.

Sample Homework

“‘Ancient Aliens’ is misleading because in the show, they present Erich von Däniken arguing for the claim that aliens visited the Earth long ago. But von Däniken wants you to believe that so you will buy his books and make him rich.”

Another Example: AGW Conspiracy

Global warming “is a multibillion-dollar worldwide industry, created by fanatically anti-industrial environmentalists, supported by scientists peddling scare stories to chase funding, and propped up by compliant politicians and the media.”

Distribution Fallacy

The distribution fallacy is committed when we assume that individuals have the properties of groups they belong to.

Lingnan has an excellent philosophy department.I am a philosopher at Lingnan._________Therefore, I am an excellent philosopher.

Distribution Fallacy

Kooks and quacks will often try to make their theories sound better “by association”:• Having a PhD.• Making one’s work sound “science-y”.• Debating serious scholars.• Associating oneself with respectable

institutions (Stanford, Smithsonian, etc.)

Genetic Fallacy

The genetic fallacy seeks to evaluate a claim on the basis of its origin.

So, for example, someone might say, “Eugenics is wrong, because the Nazis began it and did horrible things for its sake.”

Eugenics may be wrong, but the fact that the Nazis began it is irrelevant to this claim.

False Balance

False Balance

Often newspapers will present two sides of an issue equally to provide “balance.”

Objectivity is good and biased reporting is bad. But it is the responsibility of the news media to present things in a way that accurately reflects what we know to be true.

False Balance

False balance happens when:• An issue is presented as having two sides when

no knowledgeable experts disagree.• Two sides to an issue are presented equally

when one side has much more evidence than the other.

• One side is allowed to present fallacious arguments designed to mislead without the reporter(s) indicating this.

“Teach the Controversy”

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”

Tu Quoque

“Tu quoque” is Latin for “you too”. It’s a defense of an invalid argument that goes:

“You’ve made a similar argument. So you cannot criticize the flaws in this argument.”

Just because other people are doing it doesn’t make it right!

DOES THE EVIDENCE SUPPORT THE CONCLUSION?

Appeal to Popularity

“Millions of people around the world believe that we have been visited in the past by extraterrestrial beings.” – Narrator from “Ancient Aliens”


“What I am saying is that there is doubt. Millions of people believe in God in the US, so to teach to kids (again under the age of 18) only one side of something that ‘could be’ something else is misleading.” – comment from the internet


“Indian astrology is famous in the entire world. From ancient time astrology has been improving in this country. Millions of people believe in astrology with which the way of life can be smooth. Proper guidance can make a person able to combat against the problematic situations and unexpected happenings. A good astrologer can really give this guidance.” – article about astrologers in Delhi

Appeal to Tradition

“[India] is also home to some of the oldest records of ancient technologies. Ancient Sanskrit texts, dating back as far as 6,000 BC describe in varied, but vivid detail, flying machines called ‘vimanas’” – Narrator from “Ancient Aliens”

Appeal to Tradition

“With a history of more than 2000 years, Traditional Chinese Medicine (TCM) has formed a unique system to diagnose and cure illness.” – eastday.com

Red Herring

What Does It Have To Do with Aliens?

• The wings are not shaped like normal bird wings.

• The tail is vertical rather than horizontal. That’s not how bird tails look.

• The wings curve down as they move outward from the bird. This would help something fly.

• The wings are thicker in the middle and thinner at the edges. This would help something fly.

Appeal to Nature: Meat Eating

“Your statement that "we were born to eat meat" is nonsense. In using comparative anatomy to determine what man was "meant" to eat, we should look at the species most similar to man, namely the anthropoid apes — chimpanzees, gibbons, gorillas, and orangutans. Of all animals, man's digestive organs and teeth most closely resemble these apes. In captivity, some of these animals will eat meat if forced to rather than starve to death. But in the wild, all eat a vegetarian diet.”

Eating a Slow Loris

Appeal to Nature: Medicine

Taiwan has the highest per-capita incidence of UUC (upper urinary tract cancer) of anywhere in the world.Plants of the genera Ephedra and Asarum produce the toxic chemical aristolochic acid which causes UUC.TCM herbal remedies contain lots of these plants, and tests have shown they contain aristolochic acid as well.

Appeal to Nature: Homosexuality

“Because of this, God gave them over to shameful lusts. Even their women exchanged natural sexual relations for unnatural ones. In the same way the men also abandoned natural relations with women and were inflamed with lust for one another.” Romans 1:26-27

“Born This Way”

Don't hide yourself in regret,Just love yourself and you're setI'm on the right track, babyI was born this wayOoh, there ain't no other way, baby, I was born this wayBaby, I was born this way

Homosexuality in Nature

Homosexual behavior has been observed in as many as 1,500 animal species.

For example, about 1/3 of albatross couples (pairs that bond for life) are made up of two female albatrosses.

Appeal to Nature: Evolution

According to the theory of evolution, the strong survive and the weak die.Greed and aggression are traits that humans have because they have helped us in the past to succeed against people who share and are nice.So, according to the theory of evolution, greed and aggression are natural and good.But they are not good! So evolution is false.

False Equivocation

Equivocation (or “false equivocation”) is when one word is used with two meanings in the same argument, rendering it invalid.

Silly Example

God is love.Love is blind.Ray Charles is blind.So, Ray Charles is God.

False Equivocation

If evolution is true, then we should expect that creatures act selfishly.If evolution is true, then creatures ought to act selfishly.But we know that it’s morally wrong to act selfishly.Creatures ought not to act selfishly.So evolution is false.

Post Hoc Ergo Propter Hoc

https://www.youtube.com/watch?v=-_0_suZntks




THE MOST IMPORTANT LOGICAL FALLACY

The Fallacy Fallacy

This is a bad argument:

1. You have presented argument A for your claim C.

2. A is a fallacious argument.3. Therefore, C is false.

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?

What CT Can Do

• Critical thinking can show that there is no evidence.

• Critical thinking can show that the evidence is unreliable or untrustworthy.

• Critical thinking can show that the evidence does not support the claim in question.

• Critical thinking can (sometimes) reveal the other evidence you should consider.

What CT Cannot Do

Critical thinking cannot (by itself) show that a claim is false.

It checks arguments and makes sure they are not fallacious.

Only hard work and real-world investigation can show that claims are true or false.

What I Did

• Demonstrated that some arguments for Ancient Alien Theory are fallacious.

• Demonstrated that some arguments against global warming are fallacious.

• Demonstrated that some arguments against the theory of evolution are fallacious.

• Demonstrated that some arguments for/ against homosexuality are fallacious.

What I Have Not Done

• Show that Ancient Aliens Theory is false.• Show that Anthropogenic Global Warming is

true.• Show that the Theory of Evolution is true.• Show that homosexuality is good/ is bad.

ECOLOGICAL FALLACY

Ecological Fallacy

Here’s an “ecological inference”.

Countries where, on average, people consume more fat have higher rates of breast cancer.

Therefore, consuming more fat leads to a higher risk of breast cancer.

There’s a potential problem here with “confounding variables”.

Maybe countries that consume more fat, on average, are also countries that have more pollution, on average (perhaps because pollution and fat consumption both correlate with poverty). So maybe it’s the pollution and not the fat that causes breast cancer.

Ecological Fallacy

But let’s assume we know there aren’t any confounding variables. Does the premise support the conclusion:

Premise: Countries that on average consume more fat on average have higher rates of breast cancer.Conclusion: Consuming fat leads to a higher risk for breast cancer.

Ecological Fallacy

But the conclusion doesn’t follow.

Suppose that in Country A (10 people):5 people eat 4 pounds of fat a day.5 people eat 0 pounds of fat a day.

Average fat consumption: 2 pounds/ day.

Ecological Fallacy

In Country B (also 10 people):

5 people eat 2 pounds of fat/ day5 people eat 1 pound of fat/ day

Average fat consumption 1.5 pounds fat/ day.Country B on average consumes less fat.

Ecological Fallacy

Now assume that in Country A, all 5 people who consume no fat get breast cancer. And in Country B, no one gets breast cancer.

So on average, Country B consumes less fat and has a lower rate of breast cancer. Country B consumes more fat and has a higher rate of breast cancer.

Ecological Fallacy

But still, this doesn’t mean people who consume more fat are more likely to get breast cancer.

It’s the people who consume no fat that get cancer!

Ecological Fallacy

A famous (purported) instance of the ecological fallacy was Durkheim’s argument that since suicide rates in Catholic countries were lower than in Protestant countries, Catholics were less likely to commit suicide than Protestants.

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