Common Arg Flaws

Do NOT attack the author, their past acts or args, their motivations, where the arg comes

• Ad Hominem: irrelevant personal attacks used to discredit

• To attack the argument, you can only attack the support P gives C

The author uses a term (with more than one meaning) inconsistently.

• Equivocation: Ambiguous language used to hide the truth

• Ex: Public interest is what’s in best interest for public or what is popular

Two things being analogized lose their relevant similarities and are no longer an analogy

When the subject matter is outside the expertise of the authority

• Dentist’s opinion on car maintenance is not authoritative

Correlation does not imply causation

• When the LSAT implies A causes B, its 99.9% of the time wrong

3 explanations of correlation

1. B caused A

2. C caused both A and B

3. A and B are coincidences and C caused B

The P used to support C is just a restatement of C

• Ex: Girls love flowers. It’s true bc I’m a girl and I love flowers

A

A → B

________

B [VALID]

B

B → A

_________

A [INVALID]

When the author incorrectly assumes there are only two groups/choices when there are more than two

• Ex: You can either be a student or a teacher. Not true bc you would be both, or neither. Not just one or the other. Student or non student would be correct.

Could be ≠ Must be

• Even if something is 99% likely, its still not a “must”

“Is” = Descriptive “Ought” = Prescriptive

• Descriptive describes how the world is

• Prescriptive reveals values and what you care about

Common flaw is Descriptive P → Prescriptive C

• Ex: The house is on fire, we should all leave

• We need a bridge premise to take it from Descriptive → Prescriptive

• Ex: Houses on fire ought to have everyone leave. C: We all should leave.

% don’t tell us quantity and vice versa

• Ex: A wants 10% raise, B wants 50%. We don’t know who will have more money after raises bc we dont know where they started

Surveys and samplings have to be random and non-bias.

Asking students who they will vote for only tells us students, no one else.

Cant make a generalization based on small sample size or 1-2 instances

Similar to sampling error except the C will be very broad

Experiments for general C must have a control group. And a baseline of what is measured before experiment begins

Just bc the other arg is wrong, doesnt mean the opposite is true.

A = False. B ≠ True.

A is faster than B. Therefore, A is fast.

Not valid bc we don’t know how “fast” either are in absolute terms. They could still both be super slow but A is just relatively faster.

There are many ways to solve things. Just BC one solves the problem, doesn’t mean it is the sole or best solution.

Alt: Just BC one solution is inadequate, doesn’t mean the problem cannot be solved

When the argument doesn’t address the relevant issue

It addresses something in tangent or has nothing to do with issue at all

Just BC something is old / done a certain way for a long time, doesnt mean it’s right or better.

Just BC something is new, doesn’t mean its better either or that the older thing is worse.

Change for sake of change is not an argument. Has to be something that shows change is better.

There are properties that transfer vs properties that don’t

Some transfer from part → whole or from whole → part, case by case basis

Ex: Each singer could be good individually. But together, they could all be terrible. OR The group of singers could be good, but alone they are bad

When author conflates facts about world with people’s beliefs or knowledge about those facts

Ex: iPhone has Face ID. My sister knows I have an iPhone. So she knows that I have a phone with Face ID.

Flaw: Assuming that Sister knows you have phone w/ Face ID just bc you have iPhone and it is a fact that iPhones have Face ID. Maybe Sister doesn’t know bc she is not tech saavy and lives under a rock.