FLAWS

Question 1

Irrelevant Evidence

Answer 1

When an author misuses information to such a degree that they fail to provide any information to support their conclusion or provide information that is irrelevant to their conclusion.

For example:

The sky is blue. Therefore, we should go eat at McDonalds.

Note:

This example is extreme, but the principle is that the conclusion does not follow at all from the support.

Question 2

Internal Contradiction

Answer 2

Either the conclusion contradicts one of the premises or two of the premises contradict each other.

For example:

We should not do anything illegal. Driving over the speed limit, though against the law, is convenient and enables one to get to where he or she is going faster than would otherwise be possible. It carries some risks, but those risks are usually outweighed by the benefits. Therefore, we should drive over the speed limit.

Question 3

Hasty Generalization

Answer 3

A conclusion that generalizes from an unrepresentative sample, usually from one or a few to “all” or “most.”

Question 4

Unconnected Terms

Answer 4

The author illicitly assumes that the first time is equivalent to the second term, or that the first time implies the second term.

For example:

Working alone cannot lead to synergistic creations. Therefore, artists who eschew collaboration cannot create great works of art.

Note:

this is especially common when a new term is introduced in the conclusion. However, it can also be two terms in the premises that are not connected but must be connected if the conclusion is to follow.

Question 5

Appeal to Ignorance

Answer 5

An argument in which the argument concludes that something doesn’t exist or isn’t true, on the basis that no evidence against it has been found.

For example:

We have yet to find any evidence of the existence of aliens on other planets. Therefore, aliens don’t exist.

Question 6

Appeal to Ignorance - True

Answer 6

An argument in which the argument concludes that something does exist or is true, on the basis that no evidence against it has been found against it.

For example:

No one has been able to prove that aliens do not exist. Therefore, aliens do exist.

Question 7

Weakening Disproves (Conclusion)

Answer 7

An argument in which the author weakens the argument for a given conclusion and then concludes that the conclusion for that argument is false.

For example:

Jack Smith claims that the Native Americans are descendants from an East Asian nomadic tribe that came over on a land bridge. However, the source he relied on for his history was later shown to be fabricated. Therefore, his claim is false.

Question 8

Strengthening Proves (Conclusion)

Answer 8

An argument in which the author strengthens the argument for a given conclusion and then concludes that the conclusion for that argument is true.

For example:

Jack Smith claims that the Native Americans are descendants from an East Asian nomadic tribe that came over on a land bridge. Recently, archaeologists discovered a kind of boat in modern day Alaska that previously has only been discovered in East Asia. This shows that his claim was true.

Question 9

Source

Answer 9

An author attacks the person or group of people making the argument (the argument’s source) to conclude that their conclusion/claim is false and should be dismissed.

Question 10

Circular Reasoning

Answer 10

An argument in which the conclusion is identical with one of the premises.

For example:

Chocolate Green Tea Forest is the best Baskin Robins ice cream flavor, because it is better than all the rest.

Question 11

Mistaken Reversal

Answer 11

“A –> B
B
Therefore, A.

An author concludes that the sufficient condition is true, because the necessary condition is true.”

For example:

All tables have four legs. This cat has four legs. Therefore, this cat is a table.

Question 12

Mistaken Negation

Answer 12

“A –> B
/A
Therefore, /B.

An author concludes that the necessary condition is false, because the sufficient condition is false.”

For example:

All tables have four legs. This cat is not a table. Therefore, this cat does not have four legs.

Question 13

Correlation = Causation

Answer 13

The author concludes that A causes B on the basis that A and B have been observed to be correlated.

For example:

99% of people who are involved in a car accident are wearing shoes at the time of the accident. This shows that wearing shoes increases the likelihood of being in a car accident.

Question 14

Alternate Cause

Answer 14

The author argues A causes B, when there is an possible (usually obvious) alternative cause/explanation.

For example:

People who shop at Whole Foods tend to have fewer health problems and live longer than people who shop at Walmart. This shows that the food at Whole Foods promotes longevity.

Question 15

Reversed Cause

Answer 15

The author argues A causes B, when it is just as likely that the causal pattern is reversed.

For example:

A study found that those who used social media the most were also the most likely to have depression and suicidal ideation. Therefore, social media is ruining the mental health of those who use it.

Question 16

Post hoc ergo propter hoc

Answer 16

The author assumes that A causes B, just because B happened after A happened.

For example:

James drank a Fresca and then he had a heart attack. Therefore, drinking Fresca was the cause of his heart attack.

Question 17

Sole Cause

Answer 17

The author assumes that A is the only that causes B, when it’s possible that other things could also cause the same effect.

For example:

Smoking cigarettes causes lung cancer. Therefore, if we can convince all members of society to quit smoking, we can prevent all lung cancer.

Question 18

Straw Man

Answer 18

The author attacks a weaker version of the real argument to make it easier to refute.

For example:

“Center Left Politician: I think that it is reasonable to moderately increase taxes on the top income brackets to ensure that the poorest people in our country can have access to healthcare.

Angry Right Politician: So what you’re saying is that you don’t respect people’s right of private property, because you think that the government should be able to take as much of our money as it wants to give to the needy.”

Question 19

Appeal to Authority

Answer 19

The author uses an authority as the sole support of the conclusion’s truth, usually an authority from an unrelated field (thus, illegitimate authority).

For example:

It has been proposed that we should mandate measles vaccination for all school children. However, the majority of NBA players have expressed strong opposition to this measure. Therefore, it should not be adopted.

Question 20

Appeal to Popular Opinion

Answer 20

A conclusion is claimed to be true because many people believe it.

For example:

Most people think fast food is healthy. Therefore, it can’t be true that eating fast food is unhealthy.

Question 21

Appeal to Emotion

Answer 21

The author appeals to emotion (usually pity, like the etymology of the fallacy – ad misericordiam, appeal to pity) to justify the conclusion without any other support.

For example:

Attorney: Your honor, though it may appear that my client is guilty of the charges brought against her today, she should not be convicted. After all, she was brought up by a meth addicted mother in a single-wide trailer with flat tires, in which she was beaten every day with a tire iron and told she was fat and worthless.

Question 22

Survey - Biased Sample

Answer 22

An author draws a conclusion about a given population from an unrepresentative subset of the population.

For example:

Sociologist: Desiring to ascertain rates of youth video game playing in Springfield, we stationed ourselves at the local internet cafe for a full day and asked all of the recipients that visited the cafe how many hours per day they played on average. To our surprise, the average given was 14 hours per day. Based on this, we concluded that there is a serious video game addiction problem among the youth in Springfield.

Question 23

Survey - Faulty Questions

Answer 23

The survey uses bad questions (whether deliberately or not) that bias the answers. They then draw their conclusion from these biased answers.

For example:

Sociologists set up a table at the Occupy Wallstreet Movement in New York City. They put up a sign, asking for volunteers to answer a survey. One of the questions asked, “Which economic system do you prefer, capitalism or slavery?” To their surprise, every person answered “capitalism.” This shows that, contrary to expectation, the Occupiers are all capitalists.

Question 24

Survey - Lying Answers

Answer 24

The survey asks about something and then concludes something based upon the answers, but without considering that the people responding could be lying.

For example:

North Koreans were polled on the street by the government news organization as to who the greatest world leader in history was. They all answered Kim Il-Sung. This shows that North Koreans think that Kim Il-Sung is the greatest leader in history.

Question 25

Fallacy of Composition (part to whole)

Answer 25

The author conludes that something is true of the whole on the basis of what is true about the part or parts.

For example:

This car has high quality wheels. Therefore, it is a high quality car.

Question 26

Fallacy of Division (whole to part)

Answer 26

The author concludes that something is true of the parts on the basis of what is true about the whole

For example:

The LA Lakers are one of the best basketball teams. Ron Artest is a member of the LA Lakers. Therefore, Ron Artest is one of the best basketball players.

Question 27

Equivocation/Ambiguous use of a Term

Answer 27

The author uses the same term in a different way in the premises and conclusion. Alternately, the author uses the term in a way that can be wrongly understood

For example:

Lewis Lapham argues that our democracy has ceased to exist, because there has been a loss of faith. However, he is clearly mistaken, because a recently conducted survey shows that 90% of Americans subscribe to some kind of faith.

Note:

This is common as an incorrect answer choice, but rare as a correct answer choice. If it does show up, the first one is more common.

Question 28

False Analogy

Answer 28

The author compares two things that are similar in one or more respects, but are different in an important respect that weakens the argument if it is pointed out.

For example:

The Blitzkrieg was one of the most effective military maneuvers of all time. It consisted in abruptly defeating one’s opponent with a rapid and overwhelming show of force before they could react. Since sales is like war, the best tactic is to surprise one’s customers with a rapid and overwhelming sales pitch that forces them to buy.

Question 29

False Dilemma

Answer 29

The author makes a “disjunctive syllogism” without the premise that establishes the options. He eliminates one or more options and then concludes that a new option is the only option.

For example:

Jane wants to go Harvard, but that has been shown to not be an option. Therefore, she must go to Yale.

Question 30

Time Shift

Answer 30

The author assumes that conditions have remained or will remain the same over time. This can be some time period in the past, from some point in the past to the present, or from now to some time in the future.

For example:

We have been receiving heavy rain for the past several years. Therefore, we can expect to experience heavy rain this upcoming year as well.

Question 31

Relativity Flaw

Answer 31

The author draws a “positive” conclusion from “relative” premises or vice versa. Note: it can be comparative or superlative (the most/best, etc.)

For example:

Jake is the smartest kid in his high school. Therefore, he is smart.

Question 32

Numbers and Percentages

Answer 32

Normally, the author will draw a conclusion about percentages from premises about absolute numbers, or vice versa. Sometimes though, they can draw a conclusion about one kind of percent from another kind of percent, but the conclusion has an alternate explanation.

For example:

“LG sold 1,000,000 more units this year than last year. Therefore, their market share certainly saw a big increase.

Philip Morris’ market share declined by 20%. Therefore, the rate of smoking has decreased in America by 20%.”

Question 33

Is-Ought // Ought-Is

Answer 33

The author concludes from what “is” what “should” be, or vice versa.

For example:

“In nature, it is clear that the strongest animal in any kingdom rules over its fellows. Likewise, we observe in the world of men that it is the most powerful that attains unto the reins of government. Therefore, it is manifest that the strongest ought to rule.

People should eat healthy and to avoid junk food, alcohol, and cigarettes. Therefore, people do eat healthy and avoid these things.”

Note:

You cannot go from “is” premises to a “should” conclusion, or vice versa. Look up “David Hume Is-Ought Problem.”

Question 34

Appeal to Tradition

Answer 34

The author appeals to what has been done “traditionally” or “historically” to make an argument about what should be done today. This argument form is common in politics and every day speech.

For example:

Bloodletting was used for thousands of years to cure illnesses. Therefore, we should return to this older and purer form of medicine to treat diseases today.

Note:

There were many “traditions” that are clearly indefensible (e.g., human sacrifice in some cultures).

Question 35

Appeal to Consequences

Answer 35

“There are two variations.
Positive: the author concludes that something MUST be true, because if it is, then desirable consequences follow.
Negative: the author concludes that something CANNOT be true, because if it is true, then undesirable consequences follow. “

For example:

“If the six men win, it will mean that the police are guilty of perjury, that they are guilty of violence and threats, that the confessions were invented and improperly admitted in evidence and the convictions were erroneous… This is such an appalling vista that every sensible person in the land would say that it cannot be right that these actions should go any further.” (Lord Denning in his judgment on the Birmingham Six)

NOTE:

Even if bad consequences will result, a claim can still be true; even if good consequences will result, a claim can still be false.

Question 36

Slippery Slope

Answer 36

The speaker assumes that the undesirable consequences will definitely follow, but that may not be true. There may also be ways to avoid them.

For example:

Congressman: “Today, women want the vote. Tomorrow, they’ll want to be doctors and lawyers, and then combat soldiers. Before long, they will have completely enslaved all the men and reduced us to chattel slavery. Clearly then, we ought not to extend suffrage to women.” (Imagined anti-women’s suffrage argument from 1919)

NOTE:

This is an extreme example, but it shows the idea. Again, there is no way of knowing that those consquences will follow.

Question 37

Implication of Belief

Answer 37

The author assumes a person or group of people believe the implication of one of their stated beliefs. Someone believes A. A implies B. Therefore, he/she must also believe B.

FOR EXAMPLE:

John follows the Paleo diet, because he thinks it is the healthiest diet to follow. But the Paleo diet is based upon the belief that humans were originally hunter-gatherers. Therefore, John must believe that we all used to be hunter-gatherers.

NOTE:

John may not know the intellectual foundations and assumptions of the diet he follows and, thus, may not hold the belief that his other belief implies.

Question 38

Undistributed Middle

Answer 38

“The author makes an invalid inference.

A → B
C → B
∴ A → C”

FOR EXAMPLE:

“All bad people are dog owners. Jane is a dog owner. Therefore, Jane is a bad person.

NOTE:

“It’s an invalid inference. We only know that B ←s→ A and B ←s→ C, which does not allow us to conclude anything about the relationship between A and C.
“

Question 39

Red Herring

Answer 39

The speaker/writer using this tactic purposely draws attention away from the main issue by bringing up another seemingly related issue.

FOR EXAMPLE:

“Student: Students’ opinions are ignored when the university determines curricular changes and social programs. We should have a much greater voice in campus governance, because we are the chief stakeholders in this institution.

Professor: It is the faculty who should have a greater voice. Professors have no job security or control over who is hired or tenured. Additionally, they have no say in the budget. Why do you not care about the injustice we faculty are experiencing?”