LR Argument Types (LSAT)

Ad Hominem

Structure: Attacking the person instead of the claim
Gap: A person’s flaws are irrelevant to whether the claim is true
NA: The person’s character/behavior is relevant to the truth of the claim.

Ex: Lopez’s proposal to inc. teacher again after her term ends as senator

Ambiguous term Search

Uses the same word in two different ways.

Gap: using same word two different senses/equivocation hides a leap in meaning.

NA: The term/phrase means the same thing both times used.

EX: The law is a rule. Physics is a law. Therefore, physics is a rule

Whole v. Part

Assuming what is true of the part, is true of the whole

Gap: What’s true of the p is not always true of the w

NA: The characteristic of the p/w transfers properly.

EX: Each player on the team is a superstar, so the whole team must be unbeatable

False Dilema

Presents two options as if they’re the only ones.

Gap: Ignores other possibilities

NA: only the 2 stated options are possible and available

EX: Either we ban all cars from the city center, or pollution will keep rising

Irrelevant Evidence

Premises true but irrelevant to conclusion

Gap: conclusion isn’t supported by prem/arg. relies on out-of-scope premises.

NA: the evidence is actually relevant to the conclusion

EX: The mayor has lived here he whole life so the budget prop. must be sound

Appeal to authority

Claim relies on someone’s expertise where they may not be an expert

Gap: Authority might not be credible/relevant

NA: A famous actor said new medical pill is effective, so must be safe (bad)

EX: Egyptologist said mummies haunt pyramids(good)

Relative V. Absolute

Treats better/worse as good/bad

Gap: Being relatively better does not equal objectively good about absolute quality

NA: relative comp. implies something meaningful about absolute quality.

EX: My LSAT score went up points and I’m doing better. So, my score will get me into UF.

EX: This year’s sales are higher than last, so we are profitable

Temporal Fallacy

Assumes the future will be like the past

Gap: Past performance does not equal future guarantee

N/A: The future will resemble the past (No relevant changes)

EX: Dodge stock has risen every year, so it will continue to do so next year

Appeal to popularity

Argues something is true because many believe it

Gap: majority does not equal truth

NA: If most people believe it, the belief is accurate

EX: Many people believe that astrology, so it must be accurate

Equivocation on should/will/can

Confuses what should happen with what will or can.

Gap: The meaning of should/will/can shifts mid argument

NA: The meaning of should/will/can stays consistent and appropriately used.

EX: Citizens should vote, so they will vote.

Correlation → Causation

2 things occur together → therefore one cause the other

Gap: Maybe it’s coincidence/reverse causation/or a third factor

NA: No alt. cause/no reversal/no coincidence

EX: People that eat fish live longer → eating fish causes longevity

Sampling/survey/study generalization

Small biased, or limited sample → big conclusion

Gap: sample may not represent the pop; Most people in this town MUST like jazz, because concertgoers I asked said they did

NA: Sample is representative of pop and survey was conducted properly (Objective,etc.)

Plan/proposal → outcome

x policy/plan will work because of reason y

Gap: ignores factors that could block/undermine the plan.

N/A nothing prevents plan from working as intended and no unintended consequences cancels expected benefit out.

EX: The new tax law will inc. revenue because taxes will be higher (Ignores tax avoidance)

Statistical/percent v whole numbers

assumes percentage equal absolute number V.V

Gap: ignores base rates/totals

N/A: Base rates/totals don’t cancel conclusion/composition groups are of similar size or relevantly comparable

EX: a higher percentage of women pass the test so more women than men passed (not if many more men took it)

Absence of evidence = evidence of absence

Nobody proved X false → X is true

Gap: lack of evidence does not equal proof

N/A If there was evidence it would have been pound/no relevant evidence exists but is merely undiscovered

EX: no scientist has disproved UFOs, so they exist.

Necessary V Sufficient

Mistaking a condition that must be N for one that guarantee the results and V.V.

Gap: confuses must for enough

N/A Author isn’t mistaking N and S

EX: If you’re admitted to Harvard you must have high grades therefore if you have high grades you’ll be admitted

Analogy

Because things are alike in one way/ they are in another.

Gap: Similarities may not justify claim.

N/A: The 2 things comp. are sufficiently similar where relevant and no critical dif. to undermine analogy.

EX: The new software is like the old one. Since it was secure, this one must be too

Conditional claims

If A, then B. If B, then C. Therefore, if A then C

Gap: breaks chain/confuses direction/assumes if not B then not A

N/A: chain holds as stated/no missing link/author doesn’t treat contra. as orig.

EX: if someone is senator, they’re a politician. If politician, corrupt therefore senators are corrupt

Comparison args

This is better than that, so it’s good/bad

Gap: relies on irrelevant or incomplete basis of comparison

N/A The things being comp. are measured or a relevant dimension/ no overlooked alt. comp. changes the conclusion

EX: Co. A is more profitable than B, so A is good

Circular reasoning

Conclusion just restates premise

Gap: ^^

NA: Premise is valid for conclusion, but it isn’t

EX: The policy is fair because it is just