GMAT Focus Edition · GRE & GMAT Analytical Reasoning
GRE Critical Reasoning
Assessing short arguments, including strengthening and weakening them.
Eight concepts. Every short argument is conclusion plus premises plus a hidden bridge; pin that conclusion first, name the gap, then strengthen, weaken or assume against that exact claim — not a nearby topic.
- GMAT Focus Edition
- Medium level
- 8 concepts
- 5 practice questions
1Pin the conclusion before the choices
A Critical Reasoning paragraph argues for one main claim. That claim is the conclusion; the other sentences are premises offered as support. Find the conclusion first — the sentence the rest of the paragraph is trying to justify — and label premises separately before you open the options.
Most wrong answers attack a side fact, defend a different claim, or stay merely on-topic. If you have not named the exact conclusion, you cannot tell which choices miss it.
Figure. Pin the conclusion first — the one claim the premises are trying to establish — before you open the answer choices.
Label the argument
- Spot the claimAsk which sentence the others try to justify. Cue words: therefore, so, thus, should, must — or the author's recommendation.
- List premisesMark the supporting facts as premises. They stay true in strengthen/weaken items unless a choice overturns one.
- Ignore choicesDo not read A–E until conclusion and premises are written in a short scratch line.
Paragraph: Last year the library extended evening hours. Working-adult visits rose. The city should fund further evening hours to raise adult use. Which sentence is the conclusion?
- Last year the library extended evening hours
- Working-adult visits rose
- The city should fund further evening hours to raise adult use
Should fund further hours is the claim the paragraph urges. The hour change and the rise in visits are premises offered as support. Treating either fact as the conclusion would make strengthen/weaken answers aim at the wrong target.
2The assumption is the unstated bridge
Premises rarely entail the conclusion by themselves. The missing link — an unstated idea that must hold for the premises to support the conclusion — is the assumption. State it in one blank sentence: This only works if ______.
Almost every strengthen, weaken and assumption stem targets that bridge. A choice that is true and topical but leaves the bridge untouched is a distractor.
Figure. The assumption is the unstated middle link. Without it the premises do not reach the conclusion — state it as this only works if ___.
Name the gap
- Write C and PConclusion on one line; premises on the next. Leave a blank between them.
- Fill the blankAsk what must be true for those premises to justify that conclusion. That sentence is the working assumption.
- Use it on choicesStrengthen reinforces the blank; weaken breaks it; assumption questions ask for it directly.
Argument: Employees who completed the new training scored higher on reviews, so the training improves performance. Which best names the unstated bridge?
- Some employees dislike training days
- Trained and untrained employees were otherwise comparable, so training (not another difference) explains the higher scores
- Review scores are printed on a 1–5 scale
The leap from higher scores among trainees to 'training improves performance' needs the groups to be comparable aside from training. Dislike of training days and the score scale are topical facts that do not bridge premise to conclusion.
3Weaken by breaking the bridge
A weakener makes the conclusion less likely while leaving the stated premises intact. The usual move is to break the assumption — often by offering an alternative cause for the same observed effect, or a counterexample the argument overlooked.
A choice that contradicts a premise outright is rarely needed; a choice that is merely related to the topic without touching the gap does not weaken. Pin the conclusion, then ask: which option opens a live alternative path to the same evidence?
Figure. A weakener leaves the stated premises intact and attacks the bridge — rival cause, counterexample, or scope mismatch.
Weaken workflow
- Lock conclusionRestate the exact claim you must make less likely.
- Name the bridgeUsually: nothing else explains the effect, or the sample matches the target population.
- Find the breakPrefer an alternative cause, a rival explanation, or a case where premises hold and the conclusion fails.
Argument: Sales rose 20% after we redesigned the website, so the redesign caused the increase. Which most weakens this?
- Some customers still prefer phone orders
- A major competitor closed the same month the site was redesigned
- The redesign used a blue colour palette
A simultaneous competitor closure offers another cause for the sales rise, so redesign-as-cause is less secure. Preferring phone orders and the colour palette are on-topic but do not open an alternative explanation for the 20% rise.
4Strengthen by defending the bridge
A strengthener makes the conclusion more likely without restating it. The usual move is to reinforce the assumption: rule out a rival cause, show the groups were comparable, or add evidence that the sample matches the population the conclusion names.
Do not confuse strengthen with assuming the conclusion. A choice that simply repeats the claim adds no new support. Ask whether the option closes a hole a weakener would have opened.
Figure. A strengthener defends the assumption — rules out a rival cause or shows the sample matches the population — without restating the conclusion.
Strengthen workflow
- Lock conclusionSame claim you would attack on a weaken stem — now you defend it.
- List rivalsName the alternative causes or sampling gaps a hostile reader would raise.
- Close one holePick the choice that rules out a rival or affirms a necessary condition — not a paraphrase of the conclusion.
Argument: Employees who took the new training scored higher on reviews, so the training improves performance. Which most strengthens this?
- Training improves performance for every team that uses it
- Before training, both groups had identical average review scores
- Some employees skipped optional modules
Equal prior scores close the rival that trainees were already stronger, so the later gap better supports training-as-cause. Option A restates the conclusion (assuming what must be shown). Skipping modules, if anything, muddies the claim rather than defending the bridge.
5Negation test for necessary assumptions
On assumption stems, the correct choice is a claim the argument needs. The negation test finds it: negate the choice; if the argument collapses, the choice was necessary. If the argument still stands after negation, the choice was optional colour, not the bridge.
Necessary is stricter than helpful. A fact that would strengthen but is not required fails the test. Prefer the gap the premises leave open over a broad claim the author never needed.
Figure. Negate the choice: if the argument collapses, the choice was necessary. If it still stands, the choice was not required.
Negation test
- State the gapWrite the one-sentence bridge before reading choices.
- Negate each contenderForm the opposite: not representative, some other cause, safety unchecked.
- Keep the breakerOnly the negation that makes premises fail to support the conclusion is the required assumption.
Argument: The new medication reduced headaches in the study group, so it will help the general population. Which assumption is required?
- The study group is representative of the general population for this effect
- Headaches are the most common complaint in clinics
- The medication is less expensive than older drugs
Negate A — the group is not representative — and the leap to the general population fails. Negating B or C leaves the study-to-population bridge untouched; cost and clinic prevalence are optional extras, not required assumptions.
6Correlation is not causation
Many GRE-style arguments move from A happened, then B changed to A caused B. That leap assumes no rival cause and no reverse causation. Spotting the correlation-to-causation gap tells you what weakeners and strengtheners must do.
A weakener often names a simultaneous change that could produce the same effect. A strengthener often shows the effect appears when the rival is absent, or that the groups matched before the change. Do not treat a time order alone as proof of cause.
Figure. A then B is not A caused B. Weakeners name a rival cause or reverse causation; strengtheners rule those out.
| Stem job | What to look for | Classic miss |
|---|---|---|
| Weaken | Alternative cause in the same window | A true but off-gap fact about the topic |
| Strengthen | Rival ruled out / groups matched beforehand | Restating that A caused B |
| Assumption | No other cause (or reverse cause) explains B | A helpful detail the argument does not need |
Argument: After City A installed speed cameras, accidents fell 30%. Therefore cameras cause fewer accidents. Which most weakens this?
- Drivers dislike being photographed
- In the same period the city lowered speed limits and added roundabouts
- Cameras were painted yellow
Lower limits and roundabouts are simultaneous changes that can explain the drop, so cameras-as-cause is weakened. Dislike of photos and camera colour do not supply an alternative cause for the accident decline.
7A sample is not automatically the whole
Arguments often study a trial group, a survey panel or one city and conclude about a wider population. That leap needs representativeness: the sample must match the target on the traits that matter for the effect.
Assumption stems often hide here. Negate representativeness and the generalisation collapses. Strengthen by showing the sample matches; weaken by showing a relevant mismatch — age band, severity, setting — not by attacking an unrelated detail.
Figure. A trial group or one city is not automatically the whole. The leap needs representativeness on the traits that matter for the effect.
Sample check
- Name both groupsWho was measured, and whom does the conclusion claim to cover?
- Ask the matchOn the traits that could change the result, are they alike?
- Act on the stemAssume the match; strengthen by affirming it; weaken with a relevant mismatch.
Argument: A breakfast study of 40 urban prep-school seniors found higher test scores among breakfast eaters, so schools nationwide should serve breakfast to raise scores. What assumption is required?
- Those seniors are representative of the wider student populations the nationwide policy would cover
- All students dislike cafeteria food
- Tests are always given in the morning
The leap from one prep-school senior sample to a nationwide policy needs representativeness. Negating A — those seniors are not representative of the wider populations — collapses the generalisation. Cafeteria dislike and morning testing are optional colour that do not bridge sample to population.
8Stay inside the argument's exact scope
Right answers act on the conclusion's exact claim — the same population, timeframe and effect. Choices that shift topic, widen to a different group, move to another year or answer a question the stem did not ask are out of scope, however true they sound.
Before you keep an option, ask whether it changes how likely this conclusion is, given these premises. Interesting background that never touches that pair is a distractor.
Figure. Right answers act on the conclusion's exact population, timeframe and effect. Scope shifts are out even when the side fact is true.
| Shift type | What the choice does | Why it fails |
|---|---|---|
| Population | Talks about a different group than the conclusion names | Does not move this claim's likelihood |
| Timeframe | Cites another period with no link to the evidence window | Leaves the stated bridge untouched |
| Side issue | True fact about cost, taste or popularity | On-topic colour, off-gap |
| Restate claim | Repeats the conclusion in new words | Adds no support (strengthen trap) |
Argument: Our competitor lowered prices and lost profit; therefore we should never lower prices. Which most weakens this?
- Some shoppers enjoy bargain hunting
- The competitor's loss came from a warehouse fire the same quarter, not from the price cut
- Our logo uses a different typeface
A warehouse fire supplies another cause for the competitor's loss, so 'never lower prices' no longer follows from that example. Bargain hunting and logo typeface are true-sounding side issues that do not touch the price→profit bridge.
Notes
- Identify the Structure: Separate the conclusion (the main claim) from the premises (support) and locate the unstated assumption connecting them.
- Strengthen vs Weaken: A strengthener supports the assumption or adds evidence for the conclusion; a weakener attacks the assumption or offers an alternative cause.
- Assumptions: The correct assumption is a gap the argument needs to be true; negating it should make the argument fall apart.
- Scope Discipline: Right answers stay within the argument's exact scope; watch for choices that shift topic, timeframe, or population.
Formulas
- Argument core: Premises + Assumption ⇒ Conclusion.
- Weaken: introduce an alternative explanation or counterexample to the conclusion.
- Strengthen: rule out alternatives or affirm the necessary assumption.
- Negation test: if negating a choice destroys the argument, it is the required assumption.
Exam traps & shortcuts
- Pin the conclusion first; every strengthen/weaken answer must act on that exact conclusion, not a side point.
- For weaken questions, look for an alternative cause of the observed effect—correlation-to-causation gaps are common targets.
- Use the negation test on assumption questions: the choice whose opposite breaks the argument is correct.
Reference tables
Read the stem job first; the same paragraph can support opposite correct answers under different stems.
| Stem type | Cue in the question | What to do |
|---|---|---|
| Weaken | most weakens / undermines / calls into question | Break the bridge — rival cause or counterexample |
| Strengthen | most strengthens / supports | Defend the bridge — rule out a rival or affirm a needed condition |
| Assumption | assumes / depends on / requires | Name the necessary gap; confirm with negation |
| Evaluate / flaw (when present) | evaluate / vulnerable / questionable | Find which missing fact or named flaw the argument hangs on |
Most planted gaps are one of these; state yours in a blank before the choices.
| Bridge pattern | One-line form | Typical attack |
|---|---|---|
| Cause from sequence | Nothing else caused the effect | Name a simultaneous rival cause |
| Sample to population | The study group matches the target | Show a relevant mismatch |
| Plan will work | The plan's mechanism actually produces the goal | Show the mechanism fails or a blocker remains |
| No reverse cause | B did not produce A | Show the effect could drive the supposed cause |
Recap
Keep these on exam day; each one kills a planted distractor.
- Conclusion first
- Label conclusion and premises before you touch A–E.
- Name the blank
- This only works if ______ — that sentence is the bridge.
- Weaken
- Break the bridge; rival cause in the same window is the classic move.
- Strengthen
- Close a hole — do not restate the conclusion.
- Negation
- If negating a choice leaves the argument standing, it is not required.
- Scope
- On-topic but off-gap is still wrong.
Practise GRE Critical Reasoning
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- 5 exam-style questions on this topic, with explanations
- A 5-question practice set that ends the chapter
- Timed mocks scored with the real marking scheme
- Readiness tracked per topic, kept on your device