Strengthen Questions on the LSAT: How to Close the Gap

A strengthen question asks which answer, if true, most supports or most helps the argument. You are not proving the conclusion beyond doubt; you are making it more likely. The stem reads: which one of the following, if true, most strengthens the argument.

The key insight is that strengthening is about the link between the evidence and the conclusion, not about adding random favorable facts. You strengthen by protecting the argument's weakest assumption.

Every strengthen argument has a gap: the conclusion claims more than the premises strictly establish. Find that jump. Maybe the argument assumes that a correlation is causal, that a sample is representative, or that there is no alternative explanation.

Once you can name the gap, you know what a strong answer does: it makes that jump safer. Predict the kind of fact that would reinforce the link before you read the choices.

For causal arguments, strong answers rule out an alternative cause, show the cause and effect appear together, or show that removing the cause removes the effect. For arguments from a sample, strong answers confirm the sample is representative.

For arguments that depend on an unstated assumption, the answer that states or supports that assumption strengthens the argument. Affirming a necessary assumption always helps, even a little.

Watch for answers that restate a premise without adding support, answers that are favorable but irrelevant to the specific gap, and answers that actually weaken the argument. Also beware answers about a different conclusion than the one drawn.

Test each survivor by asking: if this were true, is the conclusion now more likely to hold. If the answer does nothing to the gap, it is not the strengthener, however positive it sounds.

Identify the conclusion and the premises. Locate the logical gap between them. Predict a fact that would defend that gap. Choose the answer that most directly protects the weak link, and discard restatements, irrelevancies, and weakeners.