LSAT Logical Reasoning flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Conclusion

The claim the argument is trying to establish. It is the statement the author wants the reader to accept, and it is usually supported by the other statements in the stimulus.

Premise

A stated reason offered in support of the conclusion. Premises are taken as given for the purposes of the question and are not themselves being argued for.

Background information

Contextual statements in a stimulus that explain the situation but provide no support for the conclusion. They are neither premises nor conclusions and are often distractors.

Intermediate conclusion

A claim that is supported by other premises and that itself supports the main conclusion. It functions as both a conclusion and a premise within the same argument.

Necessary assumption

A statement that must be true for the argument to have any chance of working. Negating it destroys the reasoning, which is the standard test for identifying it.

Sufficient assumption

A statement that, if added to the stated premises, guarantees the conclusion. It may be stronger than what the author actually needed or believed.

Negation test

A technique for assumption questions: deny the answer choice and check whether the argument still holds. If the argument collapses, the choice is a necessary assumption.

Strengthen question

A question asking which answer choice makes the conclusion more likely to be true. The correct answer supports the reasoning without needing to prove the conclusion.

Weaken question

A question asking which answer choice makes the conclusion less likely. The credited response typically exposes an unstated gap, an alternative cause, or a flawed sample.

Flaw question

A question asking you to identify the reasoning error in the argument. The correct answer describes the specific logical mistake rather than merely disagreeing with the conclusion.

Correlation versus causation

A common flaw in which two things occurring together is treated as proof that one causes the other, ignoring coincidence, reverse causation, or a shared third cause.

Alternative explanation

A rival account of the same evidence that does not support the author's conclusion. Its existence weakens an argument that treats its own explanation as the only one.

Unrepresentative sample

A group studied that differs systematically from the population the conclusion describes. Generalizing from such a sample is a frequent flaw in survey and study stimuli.

Equivocation

Shifting the meaning of a word or phrase between premises and conclusion. The argument appears valid only because one term is used in two different senses.

Circular reasoning

An argument in which the conclusion is restated, directly or in disguised form, as one of its own premises, so no independent support is actually provided.

Ad hominem

Attacking the person making a claim rather than addressing the claim itself. Personal characteristics are irrelevant to whether the conclusion is true.

Straw man

Distorting or exaggerating an opposing position and then refuting the distorted version. The real position is left unaddressed, so the refutation does not succeed.

False dilemma

Presenting only two options when others exist. The argument assumes that because one alternative is unacceptable, the other must be true.

Sufficient condition

A condition whose presence guarantees the outcome. In "if A then B," A is sufficient for B; A's occurrence is enough, though not required, for B.

Necessary condition

A condition that must hold for the outcome to occur. In "if A then B," B is necessary for A; without B, A cannot happen.

Contrapositive

The valid inference from "if A then B" to "if not B then not A." Reversing the terms or negating only one part produces an invalid inference.

Quantifier some

Means at least one, possibly all. "Some A are B" guarantees only overlap and supports no conclusion about most, all, or none.

Quantifier most

Means more than half. "Most A are B" permits inferences about some A being B but does not establish that most B are A.

Must be true question

A question asking which answer choice follows necessarily from the stimulus. Only entailed statements qualify; merely plausible or consistent statements are incorrect.

Most strongly supported

A question asking for the answer best supported by the stimulus. The correct choice needs strong evidential backing, though it need not be logically guaranteed.

Parallel reasoning

A question asking for the answer with the same logical structure as the stimulus. Match the pattern of premises and conclusion, not the subject matter.

Method of reasoning

A question asking how the argument proceeds, such as by offering a counterexample, distinguishing two cases, or appealing to an authority. Describe structure, not content.

Point at issue

A question asking what two speakers disagree about. The correct answer is a statement one speaker affirms and the other denies, not merely a topic both discuss.

Role of a statement

A question asking the function a specific sentence plays, such as premise, conclusion, counterexample, or concession. Identify what it supports or what supports it.

Resolve the paradox

A question presenting conflicting facts that both must remain true. The correct answer explains how both can hold, often by revealing a hidden distinction.

Evaluate the argument

A question asking which answer choice's truth value would most help determine whether the conclusion is valid. The answer is a question whose two answers cut opposite ways.

Scope shift

A flaw in which the conclusion introduces a term, group, or time frame not established by the premises. The argument quietly broadens or changes its subject.

Survivorship bias

Drawing conclusions from only the cases that remained visible while ignoring those that dropped out. The missing cases can reverse the apparent pattern.