Rank 5 by frequency | 329 questions in corpus (7.3% of all questions)
Strengthen questions present an argument and ask which new fact, if true, would most bolster the conclusion. The correct answer does not need to prove the conclusion — it only needs to make it more likely. Structurally, Strengthen is the mirror image of Weaken: identical argument, identical gap, opposite direction.
Every Strengthen stimulus contains an argument whose conclusion overreaches its premises — via a scope shift, a causal leap, a degree escalation, a temporal mismatch, or an unsupported comparison. That overreach creates an unstated assumption linking the premises to the conclusion, which is the argument's vulnerability. Your task is to find the answer that reinforces that vulnerable link.
The critical principle: the correct answer does NOT need to prove the conclusion. It only needs to make the conclusion MORE LIKELY. A modest push in the right direction beats a dramatic claim that addresses the wrong gap. The "if true" clause means you accept the answer as given and ask whether it increases the conclusion's plausibility.
Correct Strengthen answers cluster into a handful of recognizable strategies. Knowing them lets you anticipate the right answer rather than scan passively.
Eliminate an alternative explanation. The most common strategy on causal arguments. Premises show correlation; the conclusion asserts causation. An answer that rules out a competing explanation makes the claimed cause more plausible by elimination.
Affirm a necessary assumption. The argument quietly depends on an unstated premise; the correct answer explicitly confirms it. Every necessary assumption, if stated, strengthens the argument.
Provide additional evidence. A new data point that independently supports the conclusion — a separate study, a new observation, a parallel case.
Show the mechanism or pathway. Explain HOW the claimed cause actually produces the effect. Causal arguments are strengthened by evidence of the underlying mechanism.
Confirm sample representativeness. Validate that a study or survey reflects the broader population the conclusion generalizes to.
Confirm comparability. On analogies and comparisons, demonstrate that the compared items are relevantly similar in the ways the conclusion requires.
Rule out an objection. Neutralize a potential counterargument by addressing the specific worry head-on.
Validate methodology or provide before-and-after evidence. Show the cited study was properly controlled, or show the same subjects before and after the cause exhibit the predicted effect.
Variation 1 — Standard Strengthen. "Which one of the following, if true, most strengthens the argument?" Single-speaker stimulus, most common form.
Variation 2 — Strengthen EXCEPT. "Each of the following, if true, strengthens the argument EXCEPT:" Four answers strengthen; one does NOT. Critically, the correct answer is "not a strengthener" — it could be neutral, irrelevant, or even a weakener. The logical opposite of "strengthen" is "not strengthen," not "weaken."
Variation 3 — Dialogue/two-speaker format. "Which one of the following, if true, most supports [Speaker]'s argument?" You must track two separate arguments and target the right one.
Variation 4 — Principle-based strengthen. "Which one of the following principles, if valid, most helps to justify the reasoning above?" The answer is an abstract principle rather than a concrete fact. Overlaps with Principle (Supporting).
Variation 5 — Strengthen with causal stimulus. The three classic support strategies for causal arguments: eliminate alternative causes, show the mechanism, or confirm sample/data validity.
Variation 6 — Strengthen with analogy/comparison stimulus. Strengthen by showing the compared items are relevantly similar.
Step 1 — Read the stem first. Confirm it's a Strengthen question (not a Weaken, which is the easiest direction-confusion trap).
Step 2 — Read the stimulus for conclusion, premises, and gap.
Step 3 — Identify the conclusion using indicator words or by asking what the argument is trying to prove.
Step 4 — Identify the premises. Separate evidence from background.
Step 5 — Articulate the gap. What does the author assume? What objection could be raised? What alternative explanation exists?
Step 6 — Prephrase broadly. For causal arguments, think "eliminate alternatives" or "confirm mechanism." For generalizations, think "validate sample." For comparisons, think "confirm similarity."
Step 7 — Evaluate each answer. Accept as true; ask "does this make the conclusion more likely?"
Step 8 — Eliminate in order: irrelevant choices first, then weakeners, then premise restaters.
Step 9 — Compare remaining candidates. Pick the one that offers the most direct support with the fewest additional assumptions.
Step 10 — Double-check direction. Verify you're strengthening, not weakening.
The correct answer introduces new information that supports the argument, targets an unstated assumption (reinforcing it or eliminating a potential objection), and makes the conclusion more likely (without needing to guarantee it). It should not require multiple additional assumptions to connect to the argument — the more direct the connection, the stronger the support.
Correct answers often follow one of the strategies above: eliminate alternative explanation, confirm sample representativeness, provide additional evidence, show mechanism, confirm comparability, rule out an objection, validate methodology, or supply before-and-after evidence. Recognizing the pattern behind the argument tells you what shape the correct answer will take.
Trap 1 — Irrelevant/out of scope. Related topic, but doesn't bear on the conclusion's logic.
Trap 2 — Opposite (weakener). Makes the conclusion LESS likely. The most common direction-confusion trap — easy to fall for when you've lost track of which direction you're going.
Trap 3 — Premise restater. Repeats existing evidence without adding new support.
Trap 4 — Addresses the wrong gap. Supports a different aspect of the argument than the central assumption the conclusion depends on.
Trap 5 — Requires excessive assumptions. Could help, but only through a long chain of inferences that you have to supply yourself.
Trap 6 — Too extreme. A sweeping claim that goes beyond what's needed — sometimes so extreme it introduces its own problems.
Trap 7 — Tangential support. Background information that seems positive but doesn't increase the conclusion's likelihood.
Multiple gaps, one correct answer. The argument has several weaknesses; only one answer addresses the specific gap that matters. Subtle strengthening where the correct answer provides only a MODEST boost and is hard to distinguish from irrelevant options. Buried conclusions that you can't support because you can't find them.
Correct answers that seem negative. A negative-sounding fact — for example, "participants were NOT allowed to..." — that actually eliminates an alternative explanation and thereby strengthens. The surface sentiment is misleading; the logical effect is supportive. Attractive weakeners placed as traps catch students who lost direction between stem and answers.
The most common argument structures you'll see in this question type, in order of frequency: causal claims based on correlation (reinforce the causal link), recommendations or predictions based on evidence, generalizations from a sample, arguments by analogy, and arguments by elimination of alternatives.
For practice, useful examples include PT48 S1 Q3 (Difficulty 2, ruling out alternatives) on a study claiming a "sixth sense" for detecting when one is being watched; PT48 S1 Q7 (Difficulty 2, supporting an assumption) arguing that restricting calculator use is reasonable; and PT59 S2 Q1 (Difficulty 3, providing additional evidence) concluding that tropical fruits cause atypical Parkinson's.
vs. Sufficient Assumption. Sufficient Assumption answers use STRONG, absolute wording to GUARANTEE the conclusion; Strengthen answers only need to HELP and can be modest. Strong language is often correct on Sufficient Assumption but can be a red flag on Strengthen.
vs. Necessary Assumption. Every necessary assumption, if stated, strengthens — but not every strengthener is necessary. Strengthen is the broader category; both Necessary and Sufficient Assumption are specialized subcategories.
vs. Weaken. Mirror image. Identical argument structure, identical gap, opposite direction. The most common strategy on both types is to address alternative explanations — eliminate them on Strengthen, introduce them on Weaken.
vs. Principle (Supporting). Principle (Supporting) is a Strengthen question where the answer is an abstract general rule rather than a specific fact. Same task, different answer format.
Strengthen stems include some form of strengthens, supports, justifies, or helps to justify, usually combined with "if true." Recognize them and shift into gap-hunting mode with the strategies above in mind.