Strengthen vs. Weaken
Same argument. Opposite job. Learn both at once.
Strengthen and weaken questions start from the same place: an argument with a gap between evidence and conclusion. The only difference is the direction you push.
Strengthen: add a fact that closes the gap. Weaken: add a fact that breaks the link. Learn the two jobs together and each one gets easier.
Two tools go with this guide: the miss-pattern analyzer and the blind review worksheet.
Examples on this page are original. They are not real LSAT questions.
The two jobs
To strengthen
- Bridge the gap between evidence and conclusion.
- Rule out an alternate explanation.
- Show the sample is representative.
- Confirm the mechanism works as claimed.
To weaken
- Break the link between evidence and conclusion.
- Offer an alternate cause for the evidence.
- Show the sample is skewed or tiny.
- Show the evidence is unreliable.
Side-by-side on one argument
Argument: "People who meditate daily report lower stress. Meditation must reduce stress."
A strengthener
Answer: a control group with similar lives who did not meditate reported no drop in stress.
Why it helps: this rules out the worry that the meditators’ lives simply got easier. The comparison isolates meditation as the likely cause.
A weakener
Answer: the meditators also started exercising daily at the same time they began meditating.
Why it hurts: exercise is an alternate cause for the lower stress. The evidence no longer points cleanly at meditation.
Read the stem twice
One word decides the job. "Strengthens" and "weakens" ask for opposite answers, and the test writers know you are moving fast.
Watch the "except" variant: "Each of the following strengthens the argument EXCEPT" means four choices strengthen and one does not. The odd one out is usually a weakener or an irrelevant fact.
Traps both types share
- A choice that addresses a different conclusion than the one the argument makes.
- A choice that repeats a premise in new words. Restating evidence adds nothing either way.
- A choice that is true but irrelevant to the gap.
- On weaken questions, a choice the argument can live with. If it fits alongside the reasoning, it weakens nothing.
Write your own before you read the choices
The strongest drill for these two types uses one argument twice. Read the stimulus, cover the choices, and write one sentence that would strengthen the argument. Then write one sentence that would weaken it. Do this for ten arguments. You will start to see the gap before the choices tell you where it is.
Most students skip this because it feels slow. It is slow, and that is the point. On test day you will not write anything down. But the habit of generating the move yourself, built during slow practice, is what makes the right choice obvious at speed. Recognition follows generation.
Next steps
Drill strengthen and weaken in the same session. For each argument, try to write one strengthener and one weakener yourself before looking at the choices.
Put it into practice
The free diagnostic scores every question type and shows exactly where you are losing points.