LSAT Flaws

Irrelevant Evidence

Uses evidence that does not support the conclusion; “cites irrelevant data” / “draws a conclusion not warranted by the evidence”; Example: “Society has always been polarized, so scientific progress has not increased polarization.”

Internal Contradiction

The argument contradicts itself; “bases a conclusion on inconsistent claims”; Example: “Everyone should join our exclusive club.”

Overgeneralization

Uses too few examples to support a broad conclusion; “generalizes from exceptional cases”; Example: “Two friends were overcharged there, so everyone gets overcharged there.”

Lack of Evidence = False

Assumes a claim is false because it has not been proven true; “treats failure to prove a claim as denial of that claim”; Example: “No evidence of aliens exists, therefore aliens do not exist.”

Lack of Evidence Against = True

Assumes a claim is true because nobody disproved it; “treats failure to disprove as proof”; Example: “No one proved ghosts are fake, so ghosts are real.”

Weakening Evidence = Disproof

Treats evidence against a claim as complete disproof; “confuses weakening with disproving”; Example: “One rainy day occurred, so there was no drought.”

Some Support = Proven True

Treats partial evidence as absolute proof; “treats plausibility as certainty”; Example: “The suspect was nearby, so he committed the crime.”

Ad Hominem / Source Attack

Attacks the person instead of the argument; “attacks the source rather than the claim”; Example: “The senator smokes, so his anti-smoking argument is invalid.”

Circular Reasoning

Assumes the conclusion within the premises; “presupposes what it sets out to prove”; Example: “I’m trustworthy because I always tell the truth.”

Conditional Reasoning Error

Confuses necessary and sufficient conditions; “confuses a sufficient condition with a necessary one”; Example: “Studying is required to pass, so studying guarantees passing.”

False Cause and Effect

Assumes causation from correlation or sequence; “mistakes correlation for causation”; Example: “Ice cream sales rose when crime rose, so ice cream causes crime.”

Straw Man

Distorts an opponent’s argument into a weaker version; “distorts the opposing position”; Example: “You want slightly higher taxes, so you want everyone heavily taxed.”

Appeal to Authority

Relies on authority instead of proper evidence; “improperly appeals to authority”; Example: “A famous actor says this medicine works, so it must work.”

Appeal to Popular Opinion

Assumes something is true because many people believe it; “appeals to public opinion”; Example: “Most people think the movie is great, so it is objectively great.”

Appeal to Emotion

Uses emotion instead of logic; “appeals to emotion rather than reason”; Example: “Please pass me because I’ve had a hard semester.”

Survey Error

Uses flawed polls or misleading survey methods; “uses an unrepresentative sample”; Example: “An online poll of gamers proves all Americans support the policy.”

Composition Error

Assumes what is true of parts is true of the whole; “assumes what is true of the parts is true of the whole”; Example: “Every ingredient tastes good, so the dish must taste good.”

Division Error

Assumes what is true of the whole is true of each part; “assumes what is true of the whole is true of each part”; Example: “America is wealthy, so every American is wealthy.”

Equivocation / Ambiguous Term

Uses a key term in different meanings; “uses a key term ambiguously”; Example: “Humans value morals; corporations value profits; therefore corporations are moral.”

False Analogy

Compares things that differ in important ways; “treats two different cases as similar”; Example: “Relationships should work like volcanoes: hold feelings in, then explode.”

False Dilemma

Assumes there are only two choices; “fails to consider alternative possibilities”; Example: “Either the government fixes it or nobody will.”

Time Shift Error

Assumes past patterns guarantee future outcomes; “infers future results from past conditions”; Example: “The company always reimbursed me before, so it definitely will again.”

Relativity Flaw

Confuses relative and absolute claims; “confuses relative and absolute properties”; Example: “She is the tallest in class, so she is tall overall.”

Numbers vs. Percentages Error

Confuses percentages with actual amounts; “confuses percentage increase with numerical increase”; Example: “Market share increased, so total profits increased.”