How do LSAT Evaluate the Argument questions work?

LSAT Evaluate the Argument questions: the question worth asking

Last updated August 13, 2026

An Evaluate question asks which piece of information would be most useful in judging an argument. Stems read "which one of the following would be most useful to know in evaluating the argument" or ask what it would be most helpful to determine. The answers are usually questions rather than statements.

This type is Strengthen and Weaken folded into one. The credited answer is a question whose two possible answers push the argument in opposite directions — one makes it better, the other makes it worse. That is exactly what makes it worth asking.

The variable test

Take the answer, give it the most extreme YES, then the most extreme NO, and watch what happens to the argument. If the two ends land in different places, that answer is doing real work. If the argument is unmoved either way, it is out — no matter how relevant it sounds.

Try one. A town claims its new streetlights cut night-time collisions, citing a drop after installation. Candidate: "Whether traffic volume at night changed over the same period." Yes, volume fell by half — then fewer collisions is unsurprising and the lights get no credit. No, volume was steady — the lights look much better. Two ends, two verdicts. That is the answer.

Now a decoy: "Whether the streetlights use LED bulbs." Yes or no, the collision claim is untouched. On topic, entirely inert, and it will still attract picks because it is about streetlights.

How the wrong answers are built

Inert. Both answers leave the argument where it was. The most common wrong answer, and it always sounds relevant.
One-directional. Only one answer to the question matters; the other end changes nothing. A genuine Evaluate answer cuts both ways.
Already settled by the passage. If the stimulus told you, asking is not useful.
About the conclusion's desirability. Whether the outcome is good is a different question from whether the reasoning holds.
Too broad to resolve anything. A question so general that neither answer bears on this specific argument.

Because Evaluate is Strengthen and Weaken at once, the fastest route is often to find the argument's assumption first, then ask which answer probes it. The answer that interrogates the gap is nearly always the one.

Try one

A real Evaluate question, from the bank subscribers practice on

Marine biologists observed that coral reefs situated near the mouths of large rivers suffered considerably more bleaching last summer than did reefs located far from any river. Their survey covered several dozen reefs; at each site divers photographed marked sections of reef, and two members of the team then estimated from the photographs what fraction of the coral in each section had bleached. They concluded that the runoff carried downstream by those rivers is the cause of the additional bleaching, and on that basis they recommended reducing agricultural runoff in the surrounding watersheds in order to protect the reefs from further damage.

It would be most useful to determine which one of the following in evaluating the argument?

AWhether agricultural runoff contains chemicals already known to be harmful to coralBWhether reducing agricultural runoff would impose significant costs on nearby farmsCWhether the reefs near river mouths bleached more last summer than they had in previous summersDWhether the reefs near river mouths recovered from last summer's bleaching more slowly than did the reefs located far from any riverEWhether the water at reefs near river mouths reached higher temperatures last summer than the water at reefs far from rivers

Pick one to see the explanation. No account, nothing to dismiss.

Sources

LSAC — Types of LSAT Questions

Counsel is not affiliated with or endorsed by the Law School Admission Council. LSAC publishes the authoritative description of the LSAT; where this page and LSAC disagree, LSAC is right.