The False Dilemma Flaw on the LSAT: When Two Options Aren't All

A false dilemma (also called false choice or false alternative) treats a situation as having only two options when more exist. The argument then rejects one option and concludes the other must be true.

The flaw is the unstated assumption that the two options are exhaustive. If there is a third possibility, the argument collapses.

Either A or B. Not A. Therefore B.

That structure is valid only if A and B truly are the only options. The LSAT builds arguments where they are not.

Example: "The committee must either cut the budget or raise membership fees. It will not cut the budget. So it will raise fees." The flaw: maybe it could seek donations, reduce events, or do nothing. The two stated options are not the whole universe.

Watch for arguments that frame a choice as "either/or" and then eliminate one side. Ask immediately: are these really the only two options?

The flaw often hides behind reasonable-sounding rhetoric. "We must act now or accept failure" assumes there is no middle path. The LSAT wants you to notice the smuggled assumption that the alternatives are exhaustive.

On a flaw question, the correct answer describes the error abstractly. Common phrasings:

"Treats two options as the only possibilities when others may exist."

"Presumes, without justification, that because one alternative is unacceptable, another must be adopted."

"Overlooks the possibility of additional options beyond the two presented."

These describe the logical move — the unsupported assumption of exhaustiveness — not the topic of the argument.

Weaken: the correct answer introduces a third option the argument ignored.

Necessary assumption: the argument assumes there is no third option. Negate that — "there is a third option" — and the conclusion fails. So the assumption is necessary.

Parallel flaw: you will match this argument to another "either/or, not one, so the other" structure regardless of subject matter.

Confusing a false dilemma with a legitimate exhaustive choice. Sometimes two options really are the only ones (a switch is on or off). The flaw exists only when other options plausibly exist.

Calling every "either/or" a false dilemma. Check whether the argument justifies that the two options are exhaustive. If it does, there is no flaw.

Q: Is false dilemma the same as false dichotomy? Yes — false dilemma, false dichotomy, false choice, and either/or fallacy all name the same error.

Q: How common is it on the LSAT? It appears regularly in flaw and weaken questions, often disguised in policy or decision arguments.

Q: What is the fastest check? When you see an either/or framing, ask "is there a third way?" If the argument never rules one out, suspect a false dilemma.

False dilemma is one of a small set of recurring LSAT flaws. Verbloom's flaw drills name each flaw type and explain how the LSAT disguises it, so you recognize the structure quickly.

Practice at verbloom.dev.