Strengthening and Weakening Arguments

Some of the most challenging LNAT questions ask you to identify what would strengthen or weaken an argument. These questions test your ability to understand the logical structure of an argument and to evaluate how additional evidence would affect the relationship between premises and conclusion.

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The Underlying Principle

Most arguments in LNAT passages are inductive — the premises make the conclusion probable, but do not guarantee it. This means there is always a gap between what the premises establish and what the conclusion claims. Strengthening and weakening questions ask you to identify information that would make this gap smaller (strengthening) or larger (weakening).

Key Insight: You are not being asked whether the additional information is true. You are being asked what effect it would have on the argument if it were true.

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What Strengthens an Argument?

An argument is strengthened by additional evidence or information that: