LSAT Logical Reasoning: Building, Analyzing, and Attacking Arguments

Argument

A set of statements where some statements (premises) support another statement (conclusion).

Premise

Evidence, fact, or a statement that supports the conclusion in an argument.

Conclusion

The main point the author is trying to establish based on the premises.

Support

The relationship between premises and the conclusion, where premises justify or explain the conclusion.

Conclusion Indicators

Words or phrases that signal the conclusion, such as 'therefore' or 'thus'.

Premise Indicators

Words or phrases that signal premises, such as 'because' or 'since'.

Intermediate Conclusion

A conclusion that serves as a premise for a further conclusion.

Assumptions

Unstated ideas that the argument relies on to connect premises to the conclusion.

Contrast

The difference in roles between premises (support) and conclusions (main point).

Validity

An argument is valid if the conclusion must be true when premises are assumed true.

Soundness

An argument is sound if it is valid and has true premises.

Conditional Reasoning

Statements in the form 'If A, then B', where A is a sufficient condition and B is a necessary condition.

Contrapositive

The logically equivalent form of a conditional statement where terms are negated and swapped.

Quantifiers

Words like 'all', 'some', 'most', and 'none' that define the scope of claims.

Causal Claim

A statement suggesting one event causes another.

Correlation vs. Causation

The LSAT tests the ability to distinguish between mere associations and actual causative links.

Necessary Assumption

An unstated idea that must be true for the argument to hold.

Sufficient Assumption

An assumption that, if added, guarantees the conclusion.

Flaw

A common pattern of bad reasoning in an argument.

Strengthen Question

A question type that asks for evidence that makes the conclusion more likely.

Weaken Question

A question type that asks for evidence that makes the conclusion less likely.

Evaluate Question

A question type asking what information would help assess the argument's strength.

Inference Question

A question type that requires identifying what can be logically drawn from premises.

Method of Reasoning

A question type asking how the author structures their argument.

Role of a Statement

A question type asking what function a specific statement serves in an argument.

Point at Issue

A question type involving two speakers wherein the respondent must identify their disagreement.

Parallel Reasoning

Finding a new argument that matches the logical structure of the original.

Resolve the Paradox

A question type that asks for an explanation of seemingly contradictory facts.

Prephrasing

A technique that involves predicting the answer before looking at answer choices.

Scope Control

Ensuring that answer choices relate directly to the argument's premises and conclusion.

Logical Force

The degree of certainty implied by language, such as 'must' vs. 'may'.

Argument Chain

A sequence of arguments where one serves as a premise for the next.

Equivocation

Using a key term in two different senses within the same argument.

Composition Flaw

Assuming what is true of the parts is also true of the whole.

Division Flaw

Assuming what is true of the whole is true of each part.

False Dilemma

Presenting only two options when more exist.

Circular Reasoning

When the conclusion is simply a restatement of a premise.

Negation Test

A method to determine if an assumption is necessary by negating it and assessing impact.

Background Information

Statements that provide context but do not support the conclusion.

Premise-Well Supported

In LR, evaluating whether a conclusion is well-supported by provided premises.

Weakening Causal Claims

Providing counter-explanations to reduce the certainty of a causal claim.

Sampling Flaws

Drawing conclusions based on non-representative or small samples.

Common Cause Flaw

Failing to recognize that a third factor causes both the suspected cause and effect.

Method Flaw Question

A question type asking for the specific logical error in the argument.

Critical Thinking

Evaluating the structure of arguments based on logical reasoning, not factual correctness.

Test-Taking Strategy

Using consistent mental moves in predictive reasoning when tackling LSAT questions.