GMAT strengthen and weaken questions
You are asked which option most strengthens or most weakens the argument. Both act on the same place — the gap between evidence and conclusion — and the common error is the same in both: going after the evidence instead.
The evidence is given
The facts stated in the stimulus are true. An option disputing them is out of bounds. What can be attacked or supported is the inference — whether those facts license that conclusion.
- Weaken — show the gap is real: an alternative cause, a missing group, a reason the evidence would not generalise.
- Strengthen — close the gap: rule out an alternative cause, confirm the sample was representative.
- Neither — anything that leaves the conclusion exactly as well supported as before.
The reliable shapes
| If the argument | Weaken by | Strengthen by |
|---|---|---|
| Infers cause from correlation | Offering another cause | Ruling other causes out |
| Generalises from a sample | Showing the sample was unusual | Showing it was representative |
| Predicts from a trend | Showing conditions changed | Showing they held |
| Recommends a plan | Showing a side effect defeats it | Showing the mechanism works |
An option can be true, relevant and still not change the argument. The test is not whether it is interesting but whether the conclusion is more or less likely with it than without it.
Strengthen & weaken — FAQs
2 questions
No. The stimulus facts are taken as true; the inference is what is open to challenge.
Not necessarily. The test is the effect on the conclusion, not the force of the wording.
More verbal question types
Sources
Written from the test board's own published material and checked on 1 October 2026.