Common Argument Flaws

Credit to aobonyo on Quizlet

Ad Hominem

Attacking the author, their actions, credentials, or motivations.

Example: The Congressman voted to change the law because he had significant investments in the industry, so the bill should not be passed.

Equivocation

Shifting the meaning; the author uses a term with more than one meaning inconsistently.

Example:
"Public interest" is used to describe what is in the best interest of the public (i.e. schools, economy, roads, etc.)

VS.

when it is used to describe what the public is interested in (i.e. sports, political scandal, venues, etc.)

Weak Analogy

The two things being analogized are neither relevant nor similar, so the analogy cannot continue.

Example: Attacking LSAT questions is like attacking enemy starships.

Irrelevant Appeal to Authority

Appealing to authority where the subject matter is outside the expertise of the authority.

Example: Appealing to a dentist's opinions on an automotive maintenance is not authoritative.

Causation vs. Correlation

Concluding that because A is correlated with B, A CAUSED B. But, this often not the case on the LSAT

Correlation does not = causation
Causation = correlation

The other possible explanations:

1) B caused A
2) A and B are caused by C
3) A and B are correlated only and X caused B

Example: "A new speed limit sign was put up and accident rates dropped dramatically afterwards. The only plausible explanation was that the signage dropped that accident rate."

This COULD be the case, however without further explanation, this statement is flawed. Reasons such as a decreased number of cars on the road

Circular Reasoning

the author is assuming what they're trying to prove. This is indicated by the fact that the conclusion restates the premise(s) .

Premise and conclusion are the same.

Example: "Everything I say is true because, if I say it, it is ultimately truthful."

Confusing Necessary and Sufficient

Saying that X is necessary for Y when, in reality, X is sufficient for Y and Y is necessary for X

X --> Y (correct)

Y --> X (incorrect)

False Dichotomy

Pretends to divide the universe into two binary halves, when really this divide is not a true contradiction

Example: Cats and Dogs

Probability vs. Certainty

"Could be" does NOT = "must be"

Even if something is 99% likely it is not certain/guaranteed/valid.

"Is" vs. "Ought"

This involves confusing the descriptive ("is") for the prescriptive "ought").

Descriptive describes how things are. Prescriptive relays values.

*The LSAT will often lump the two together using a descriptive premise that leads into a prescriptive premise. However, we need a bridge premise that like the descriptive with the prescriptive.

% vs. Quantity

Percentages don't necessarily reveal quantity and vice versa.

You have to account for proportions.

Generalization from Survey/Sampling

Surveys and samples must be random/non-biased.

You cannot make a generalization based on small sample size or based on one or two incidents.

Be wary of questions that make broad generalizations based on limited Samples, narrow samples, or sample errors

Generalizations from Experiment Errors

Generalizations from experiments are flawed if the experiments:

1) Do not have a control group (not being experimented on for sake of comparison).

2) Do not establish the baseline of what is being measured.

Failing Argument /= Validating Contradiction

If someone's argument is wrecked, that doesn't mean that the opposite of their conclusion is true.

There could be other reasons that support their argument that have to first be addressed. Also, one has to validate the contradiction before it can be accepted.

Relative vs. Absolute

Concluding that something is absolute from a relative comparison is flawed.

Example: "A is greater than B. Therefore, A is great."

It is only greater relative to B; A is not great absolutely (unless proven otherwise).

One Solution /= The Only Solution

Just because one solution solves a problem doesn't mean that particular solution is he only solution nor does it mean it is the best solution.

There are many ways to solve a problem.

Red Herring

The argument doesn't address the relevant issue; rather, it address some tangent that otherwise captures the readers attention.

Traditional Fallacy

The fact that something is old or has been done a certain way for a long time doesn't mean that it is right or better.

Example: Slavery

Novelty Fallacy

The fact that something is new doesn't mean:

-That it is the best course of action
-That is is better than the old version
-That the old thing is irrelevant or ineffective

Part vs. Whole

Must think of this flaw in terms of properties that do transfer and properties that don't.

-Transferable properties can transfer from whole-to-part and from part-to-whole

-Untransferable properties cannot transfer from whole to part and from part to whole

Beliefs vs. Facts

The assumption that because of X, Y is common knowledge, so anyone who knows X knows Y.

This assumption is merely a belief, not a fact, unless stated otherwise.

(i.e. a person is told about Y and so their knowledge is a fact, not an assumption)

Lack of Evidence = False Claim

The absence of positive evidence for a conclusion is used to undermine the conclusion's validity.

Example: X is false because you cannot prove that X is true.