LSAT key terms

A statement offered as evidence or support for a conclusion. In an LSAT argument the premises are the stated reasons, and you treat them as true for the sake of evaluating the reasoning.

The claim an argument is trying to establish. It is what the premises are meant to support, and it is often flagged by words such as therefore, thus, or hence.

An unstated belief the argument must rely on for its conclusion to follow from its premises. Locating it is often the key to strengthening, weakening, or evaluating the reasoning.

A conclusion drawn from given information rather than stated outright. On this exam it must be fully supported by the text, not merely plausible or consistent.

A property of deductive arguments in which, if the premises are true, the conclusion must be true. Validity concerns logical structure only, not whether the premises are actually true.

A property of deductive arguments that are both valid and have all true premises. A sound argument guarantees a true conclusion, so soundness is stronger than validity alone.

Something that must hold for a claim to be true, though it may not be enough on its own. It is commonly signaled by phrases like only if or requires.

Something that, if present, guarantees a result. It is enough by itself, even though other routes to the same result may also exist.

A statement of the if-then form, linking a sufficient condition to a necessary condition. Diagramming these accurately is essential for spotting mistaken reversals and negations.

The logically equivalent version of a conditional statement, formed by reversing and negating both parts. If A then B becomes if not B then not A.

The mistaken reversal of a conditional statement. If A then B does not imply if B then A, and treating it as though it does is a common tested flaw.

An assertion that one thing produces or brings about another. Supporting one requires ruling out reverse causation, coincidence, and other explanations for the same evidence.

A pattern in which two things occur together or vary together. Correlation alone does not establish that one causes the other, a distinction the exam tests repeatedly.

A different reason that could account for the same evidence the argument cites. If a plausible one exists, an argument's causal or explanatory conclusion is seriously weakened.

A question type asking you to add information that makes the conclusion more likely to follow from the premises. The correct answer supports the reasoning without needing to prove it.

A question type asking you to add information that makes the conclusion less likely to follow. Correct answers usually attack a hidden assumption or supply a rival explanation.

A defect in reasoning in which the conclusion does not follow from the premises. Flaw questions ask you to describe in general terms what is wrong with the argument's structure.

A flaw in which the conclusion is smuggled into the premises, so the argument assumes what it set out to prove. It provides no independent support for the claim.

A fallacy that attacks the person making a claim rather than the claim itself. The character or motives of a speaker are irrelevant to whether the reasoning is sound.

A fallacy of distorting or exaggerating someone's position so it can be easily attacked. The refutation then misses the actual claim that was made.

A flaw of drawing a broad conclusion from a sample that is too small or unrepresentative. The evidence gathered is insufficient to support the sweeping claim being made.

A flaw in which one word is used with two different meanings inside a single argument, making the reasoning appear valid when it is not.

A specific case showing that a general claim or rule is false. It is one of the most direct ways to weaken a universal statement or a proposed principle.

A general rule or value that justifies a particular judgment or decision. Principle questions ask which rule, if accepted, would support or undermine the reasoning given.

A situation in which two facts seem unable to be true at the same time. Resolve questions ask you to explain how both can hold simultaneously.

A comparison used to carry reasoning from one situation over to another. Such arguments depend on the two cases being similar in the respects that actually matter.

The range of subject matter or degree that an argument or answer choice covers. Choices that reach beyond the argument's scope are typically incorrect.

A word such as all, some, most, or none that specifies how many members of a group have a property. Reading these words precisely is essential to drawing valid inferences.

Reasoning that moves from general rules to a guaranteed specific conclusion. If the premises are true and the form is valid, the conclusion cannot be false.

Reasoning that generalizes from specific observations to a probable conclusion. The conclusion is likely rather than guaranteed, so it can be strengthened or weakened by new evidence.

The central claim the passage is written to convey. It is broader than any supporting detail and should capture the author's overall message rather than a single example.

The author's overall aim in writing the passage, such as explaining a phenomenon, evaluating a theory, or arguing for a position. It is usually expressed as a verb phrase.

The author's stance toward the subject, ranging from strong approval to sharp criticism. Word choice and tone in the passage reveal it even when no opinion is stated directly.

The way a passage is organized, such as problem then solution, old view versus new view, or claim followed by evidence. Recognizing the pattern helps you locate information quickly.

The role a particular sentence or detail plays in the passage, such as supplying evidence, introducing a counterargument, or qualifying a claim already made.

Two short passages presented together, often on the same topic but reflecting different viewpoints. Questions frequently ask how each author would respond to the other.

A word that limits the strength of a claim, such as usually, often, or in most cases. Qualifiers make a statement easier to defend and should never be ignored when judging answers.

A point where the author acknowledges an opposing view or admits a limitation before restating the main position. It signals nuance rather than agreement with the opposing side.

The specific claim or interpretation the passage sets out to establish. It is more precise than a general topic and is usually supported by the rest of the text.

A question asking about a fact explicitly stated in the passage. The correct answer must be directly supported by the text rather than inferred or supplied from outside knowledge.

Working out what a word means from the way it is used in the passage, which may differ from its most familiar dictionary definition. Surrounding sentences supply the needed clues.