Classic Flaws

Bad Conditional Reasoning

Occurs when the author reads the conditionals supplied in the premises incorrectly

Play by play

1. There are conditional premises

2. Author concludes something by reading the conditional premises backwards without negating

Or

1. There are conditional premises

2. Author concludes something by negating the conditional premises and reading it forwards

Bad Casual Reasoning

Play by play

1. Author sees two things that are correlated

2. Author concludes that one of those things causes the other

(Remember omitted options)

Part to whole and whole to part

Parts do not equal whole

Play by play

1. Person says a member of a category has a property

2. Person concludes that the category itself also has that property

Or

1. Person says a category has a property

2. Person concludes that a member of that category also has that property

Overgenralization

Parts do not equal all parts

Takes something small and turns it big

Play by play

1. Person talks about something having a property

2. Person concludes that a bunch of other things also have that property

Survey problems

Play by play

1. There is a survey

2. Person concludes something based on that survey

3. There are all kinds of silent things wrong about the survey

Always assume surveys are done with the greatest possible incompetence

Loopholes to these questions includes: biased sample, biased questions, small sample size, other contradictory surveys, people who lie on surveys

False Starts

Researchers here always assume that the two groups are the same in all respects except the ones called out as part of the study, except there is always a possibility of the two groups being different in other ways

• deployed on almost every stimulus that has two groups and a comparison between them

Play by play

1. There is a study of the two groups

2. Researcher assumes the two groups are the same in all respects except those pointed out as part of the study

3. Researcher concludes that the differences in the study results are due to one key difference the study is focusing on

Possibility does not equal Certainty

It’s fine to say that if someone hasn’t proven their conclusion, then it’s not necessarily true. But stopped there. Because it does not mean it can’t be true

• facts are not affected by the failure of an argument

• Lack of evidence does not equal evidence of lacking

  • Wrong: it’s not necessarily true, so it can’t be true

• Proof of evidence does not equal evidence of proof

  • Wrong: It could be true, so it must be true

Implication

Tells people what they believe

Opinion and facts do not go together

Play by play

1. Someone has a belief

2. Someone else mentions a factual implication of that belief

3. Someone else claims the first person believes the implication of the belief

False Dichotomy

Pretends there are only two options when there really could be more

Play by play

1. Person outlines two possible options

2. Person eliminates one of the options

3. Person concludes the second option must be the case

Two ways this could go wrong

1. Limiting a spectrum

   1. Three options: You can go up, down, or stay the same

   2. Two tricks to see through every limited spectrum:

      1. Not more does not equal less

      2. Not less does not equal more

2. Limiting options

   1. Pretends that there are only two options when there could be more

Straw Man

These arguments “respond” to an opponent by “mishearing” what was said to them

Play by play

1. Person 1 makes a claim

2. Person 2 responds to en entirely different claim, but pretends they responded to person 1

Key phrases include: “so what you’re really saying is” or “so what you mean is”

Ad Hominem

Play by play

1. Person makes a claim

2. Person 2 talks about how person 1 is somehow awful

3. Person 2 concludes that the first person’s claim is false

A proponent biased 4/against a position does not affect the truth or false of that position

Circular Reasoning

Assumes the conclusion is true before doing the work of proving it so

• Often the argument will rule out objections to the conclusion simply because the objections are incompatible with the conclusion

Play by play

1. Person concludes something

2. Person supplies premises that assume the conclusion is already true

When you repetition between the premises and conclusion, it is this flaw

Equivocation

Happens when the author changes the meaning of a word throughout the argument

Play by play

1. Someone uses a word or idea, intending one of its possible meanings

2. Someone concludes something using the other possible meaning of the word or idea

Appeal Falacies

About turning someone’s opinion into fact

Play by play

1. Person says that a person or group believes something

2. Person concludes that thing must be true

Happened in either two ways: Invalid appeal to authority or Invalid appeal to public opinion

• invalid appeal to authority happens when the author uses a non-expert opinion to support their conclusion

• Invalid appeal to public opinion is invalid because people are unreliable

  • A high percentage of random people believing anything has very little bearing on whether something is actually true

Irrelevant

Occurs when premises are entirely unrelated to the conclusion

Play by play

1. Author supplies a few premises

2. Author concludes something that is unrelated to those premises

Percentage ≠ Numbers

Premises about numbers almost never lead to conclusions about percentages and vice versa

Play by play

1. Person says a percentage went up

2. Person concludes that the associated real number went up

Or

1. Person says a real number went up

2. Person concludes that the associated percentage also went up

They purposefully don’t mention group size and assume it remains the same