What "if true" actually instructs you to do
"Which of the following, if true" is an instruction: treat each answer choice as a brand-new fact you must accept, then ask what it does to the argument. You are not deciding whether the answer is realistic — you are told to assume it is.
This matters because it removes "that seems unlikely" from your toolkit. On these questions, an answer's real-world plausibility is irrelevant. The only question is the effect it has once you grant it: does it support the conclusion, undermine it, resolve a discrepancy, or settle a dispute?
So when you see "if true," mentally stamp each answer with "suppose this is a fact." Then evaluate its impact on the argument, not its believability.
Where you'll see it
The "if true" instruction appears on the question types that ask you to bring in outside information and measure its effect. That's a different job from the inference questions, which forbid outside information.
| Stem family | What you do with the answer | Outside info? |
|---|---|---|
| "…if true, most weakens/strengthens" | Accept it, then test its effect on the conclusion | Yes — that's the point |
| "…if true, most helps to resolve" | Accept it, then see if it explains the discrepancy | Yes |
| "…must be true / most strongly supported" | Derive it only from the stimulus | No — stay inside the text |
The contrast in the last row is the key. Inference questions ("must be true," "most strongly supported") ask what follows from the stimulus and nothing else. "If true" questions hand you new facts on purpose. Mixing these up is a common source of wrong answers.
Why the test uses this phrase
The phrase exists to stop you from defending the argument or arguing with the answer. Without "if true," a strong student might reject a perfectly good weakener by saying "but that probably wouldn't happen." The instruction closes that escape hatch.
It also lets the test introduce powerful new facts that would be unfair to require you to verify. You don't have to know whether a claim is accurate; you only have to reason about what would follow if it were.
Treat "if true" as permission to be hypothetical. Your task is conditional: given this new fact, what happens to the argument?
The common mistake: rejecting an answer for being unrealistic
The classic error is eliminating the credited answer because it sounds far-fetched. On an "if true" question, "that's implausible" is not a reason — you were instructed to assume it's true.
For example, if a weaken answer says a study's entire sample was misrecorded, you might think "that rarely happens." Doesn't matter. If it's true, it guts the evidence — and on a weaken question, that's exactly what you want.
Catch yourself whenever your reason to eliminate is about likelihood rather than effect. Swap the question "could this happen?" for "if this is a fact, what does it do to the argument?"
Frequently asked questions
What does "if true" mean on the LSAT?
It instructs you to accept the answer choice as a given fact and then evaluate its effect on the argument. You don't judge whether the answer is realistic — the test tells you to assume it is and asks what follows.
Which question types use "which of the following, if true"?
Mainly the ones that bring in outside information: strengthen, weaken, and resolve-the-paradox questions. Inference questions like "must be true" and "most strongly supported" do the opposite — they ask what follows from the stimulus alone, with no new facts.
Can I eliminate an "if true" answer because it seems unlikely?
No. Plausibility is off the table once a stem says "if true." Eliminate based on the answer's effect on the argument — whether it actually strengthens, weakens, or resolves — not on whether it would happen in the real world.
How is "if true" different from "must be true"?
"If true" hands you a new fact to test against the argument. "Must be true" asks what is already guaranteed by the stimulus, using no outside information. One adds information; the other stays strictly inside the text.
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