Flaw Types Flashcards
Different kinds of flaws contained within LSAT Flaw questions. (16 cards)
“The car wouldn’t start this morning, so the battery must be dead.”
Failure to Consider Alternative Possibilities/Overlooked Explanations
(Fails to consider: The issue might be the starter, fuel, or ignition.)
“People who eat more vegetables tend to live longer, so vegetables must cause longevity.”
Correlation vs. Causation
(Correlation ≠ causation — maybe healthier people in general eat more vegetables.)
“Without a college degree, one cannot become a doctor. So, anyone with a college degree is a doctor.”
Necessity vs. Sufficiency
(Confuses a necessary condition with a sufficient one.)
“All students at this university value education. Therefore, education in this country is highly valued.”
Scope Shift - general mismatched concepts between evidence and conclusion
(Shifts scope from a group (students at this university) to a broader population (the country).)
“A survey of 20 people at a yoga retreat found that 90% believe in holistic medicine, so most Americans must believe in it too.”
Representativeness - the study/survey does not involve a large enough quantity or variety of subjects/respondents
(Non-representative sample — doesn’t reflect broader population.)
“Only man is rational. No woman is a man. So no woman is rational.”
Equivocation - a term is used inconsistently
(Uses “man” in two different senses — as a species vs. as a gendered term.)
“Each member of the choir sings beautifully, so the choir must sound beautiful together.”
Part vs. Whole
(Assumes the whole has the same properties as each part.)
“Lying is immoral because it’s wrong to lie.”
Circular Reasoning - the conclusion relies on the evidence and vice versa
(The conclusion just restates the premise in different words.)
“The majority of data suggest the new drug is ineffective. Therefore, we should prescribe it widely.”
Evidence Contradicts Conclusion
(Conclusion contradicts the provided evidence.)
“This year, more people died from heart disease than from cancer. So heart disease is deadlier than cancer.”
Number vs. Percent
(Confuses raw numbers with relative risk or rate.)
“Most employees believe the CEO is unethical. Therefore, the CEO must be unethical.”
Belief/Opinion vs. Fact
(Belief is not the same as objective evidence.)
“Senator Garcia argues for education reform, but she failed math in high school. So we shouldn’t trust her argument.”
Ad Hominem Attack - the author attacks the argument-maker rather than the argument
(Attacks the person, not the reasoning.)
“There’s no proof aliens exist, so they definitely don’t exist.”
Absence of Evidence is Evidence of Absence
(Lack of evidence is not proof of nonexistence.)
“A celebrity chef says this investment strategy works, so we should all follow it.”
Inappropriate Reliance on Authority
(The authority cited lacks relevant expertise.)
“The defendant might have committed the crime. Therefore, he is guilty.”
Possibility vs. Certainty
(Confuses possibility with certainty.)
“The debate team is nationally ranked, so every member must be an expert debater.”
Group vs. Member
(Assumes what’s true of the group applies to each individual.)
