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Fallacies 1.

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Presentation on theme: "Fallacies 1."— Presentation transcript:

1 Fallacies 1

2 arguments

3 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?

4 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’.”

5 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.

6 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.

7 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.

8 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.

9 fallacies

10 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.

11 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.)

12 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?

13 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.

14 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!

15 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.

16 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.

17 Yes, There Is Evidence Presented
Is the evidence reliable and trustworthy? No  Unreliable and untrustworthy evidence can be misleading. Yes  Keep critically thinking!

18 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.

19 Lies From “Ancient Aliens”:

20 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.”

21 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.


23 Mere Opinions Sometimes the premise strongly supports the conclusion, but the premise is just someone’s opinion.


25 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.

26 Expert #1: Dr. Algund Eenboom
Dr. Algund Eenboom is a doctor. A doctor of dentistry. He is not a scientist or a historian.

27 Google Search Dr. Algund Eeenboom (Leer, Deutschland) geb 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.

28 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.

29 Misinterpretation

30 Misinterpretation

31 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!

32 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.

33 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.

34 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.


36 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.”

37 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.

38 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.

39 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.

40 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.”

41 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.

42 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.

43 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.


45 Straw Man Fallacy

46 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.

47 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.

48 Example: Evolution


50 Our Common Ancestor

51 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?”

52 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

53 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.”

54 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.

55 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.

56 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.”

57 Other Possibilities!

58 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.”

59 Straw Man Fallacy Many in Hong Kong think that President Benigno Aquino of the Philippines should apologize for the Manila bus crisis.

60 Straw Man Aquino argues:
No one should apologize for something that they did not do. 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. Therefore, the government/ people of the Philippines should not apologize.

61 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.

62 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.

63 Fallacy of the Mean The fallacy of the mean is the assumption that a “middle point” between two views is the right one.

64 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.


66 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”

67 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.

68 Martin Gregorie’s Tests

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