Get in touch: (800) 551-3410
Learn how to tackle sufficient assumption questions on the LSAT with effective strategies and examples.
Sufficient assumption questions test your ability to identify premises that, if true, would guarantee the conclusion of an argument. These questions typically ask you to find the answer choice that strengthens the argument in a way that ensures its validity.
Sufficient assumption questions on the LSAT can be identified by their specific phrasing and structure. Here's what the common question stems look like:
Sufficient assumption questions will typically present an argument with a conclusion and one or more premises. Your job is to find the answer choice that would make the conclusion valid if true.
The correct answer choice will fill in any gaps or assumptions not explicitly stated in the argument, making the conclusion logically inevitable. The answer must guarantee the conclusion.
To solve sufficient assumption questions, look for the gap in the argument and identify the answer choice that, if added to the argument, would make the conclusion logically follow. This often involves recognizing unstated premises that are necessary to the argument’s conclusion.
Below are eight sample sufficient assumption questions found in the logical reasoning section, with detailed answer explanations for each.
“An undergraduate degree is necessary for appointment to the executive board. Further, no one with a felony conviction can be appointed to the board. Thus, Murray, an accountant with both a bachelor’s and a master’s degree, cannot be accepted for the position of Executive Administrator, since he has a felony conviction.”
The argument’s conclusion follows logically if which one of the following is assumed?
(A) Anyone with a master’s degree and without a felony conviction is eligible for appointment to the executive board.
(B) Only candidates eligible for appointment to the executive board can be accepted for the position of Executive Administrator.
(C) An undergraduate degree is not necessary for acceptance for the position of Executive Administrator.
(D) If Murray did not have a felony conviction, he would be accepted for the position of Executive Administrator.
(E) The felony charge on which Murray was convicted is relevant to the duties of the position of Executive Administrator.
Answer:
A. This option outlines sufficient conditions for board appointment. Its contrapositive is:
Not eligible for board → no master’s degree or felony conviction. That doesn’t help us because Murray already has a felony conviction, so this just reiterates that he’s not board-eligible. It provides no new insight.
B. Correct. We know Murray can’t be appointed to the board because of his conviction. This statement links board eligibility to eligibility for Executive Administrator. Diagram: Eligible for Executive Administrator → Eligible for board. Since Murray isn’t eligible for the board, this implies he’s also ineligible to be Executive Administrator.
C. This is irrelevant. It simply says a master’s degree isn’t necessary to be Executive Administrator, which doesn’t help us. It’s like saying, “Sarah got a 180 on the LSAT, but a 180 isn’t required for law school admission, so she won’t get in.” That logic doesn’t hold up, and neither does this answer.
D. This misrepresents the conclusion. It assumes that if Murray can’t be Executive Administrator, it must be because of his felony conviction. But that might not be the reason, he could be unqualified for other reasons.
E. This doesn’t establish that a felony conviction definitively prevents someone from being Executive Administrator. It suggests a possible issue, but doesn’t prove a direct disqualification.
“Standard aluminum soft-drink cans do not vary in the amount of aluminum that they contain. Fifty percent of the aluminum contained in a certain group (M) of standard aluminum soft-drink cans was recycled from another group (L) of used, standard aluminum soft-drink cans. Since all the cans in L were recycled into cans in M and since the amount of material other than aluminum in an aluminum can is negligible, it follows that M contains twice as many cans as L.”
The conclusion of the argument follows logically if which one of the following is assumed?
(A) The aluminum in the cans of M cannot be recycled further.
(B) Recycled aluminum is of poorer quality than unrecycled aluminum.
(C) All of the aluminum in an aluminum can is recovered when the can is recycled.
(D) None of the soft-drink cans in group L had been made from recycled aluminum.
(E) Aluminum soft-drink cans are more easily recycled than are soft-drink cans made from other materials.
Answer:
A. This option focuses on the future use of aluminum, while the argument concerns its origin, specifically, where the aluminum in group M came from. It doesn’t address the core issue.
B. The quality of aluminum isn’t relevant here. The argument hinges on the quantity of cans, not their quality. Even if lower-quality aluminum couldn’t be reused, this option doesn’t make that claim explicitly.
C. Correct. This directly supports the conclusion. If all cans from group L were turned into cans in group M, and group L's aluminum accounts for half of M’s material, then logically, group M must contain twice as many cans as group L.
D. The source of the aluminum in group L is irrelevant. The argument is focused on what happened to that aluminum afterward, not where it originated.
E. This is a weak form of support. While it points in the same direction as C, it’s too vague. C provides definitive proof; this only hints that aluminum might be more efficiently reused than other metals, which doesn’t confirm the argument.
“A new government policy has been developed to avoid many serious cases of influenza. This goal will be accomplished by the annual vaccination of high- risk individuals: everyone 65 and older as well as anyone with a chronic disease that might cause them to experience complications from the influenza virus. Each year’s vaccination will protect only against the strain of the influenza virus deemed most likely to be prevalent that year, so every year it will be necessary for all high- risk individuals to receive a vaccine for a different strain of the virus.”
Which one of the following is an assumption that would allow the conclusion above to be properly drawn?
(A) The number of individuals in the high-risk group for influenza will not significantly change from year to year.
(B) The likelihood that a serious influenza epidemic will occur varies from year to year. (C) No vaccine for the influenza virus protects against more than one strain of that virus. (D) Each year the strain of influenza virus deemed most likely to be prevalent will be one that had not previously been deemed most likely to be prevalent.
(E) Each year’s vaccine will have fewer side effects than the vaccine of the previous year since the technology for making vaccines will constantly improve.
Answer:
A. The number of people vaccinated isn’t the point. The conclusion is about who needs to be vaccinated—everyone or just high-risk individuals—not how many people get the shot.
B. This discusses the likelihood of an epidemic, but that misses the mark. Severe flu cases can still happen without an epidemic, so this doesn’t address the core issue.
C. Be careful here. The stimulus clearly states that the program uses vaccines that only protect against a single strain. So the existence of broader-spectrum vaccines is irrelevant, they’re not part of the program.
D. Correct. This directly supports the argument. If vaccines are only effective for one year, then high-risk individuals would need annual vaccinations, just as the program recommends.
E. Side effects don’t factor into the reasoning. The program is committed to protecting high-risk individuals, implying that side effects are either minimal or not a significant concern.
“Philosopher: An action is morally right if it would be reasonably expected to increase the aggregate well-being of the people affected by it. An action is morally wrong if and only if it would be reasonably expected to reduce the aggregate well-being of the people affected by it. Thus, actions that would be reasonably expected to leave unchanged the aggregate well-being of the people affected by them are also right.”
The philosopher’s conclusion follows logically if which one of the following is assumed?
(A) Only wrong actions would be reasonably expected to reduce the aggregate well-being of the people affected by them.
(B) No action is both right and wrong.
(C) Any action that is not morally wrong is morally right.
(D) There are actions that would be reasonably expected to leave unchanged the aggregate well-being of the people affected by them.
(E) Only right actions have good consequences.
Answer:
A. The stimulus already established that reducing overall well-being is a necessary condition for something to be wrong. But sufficient assumption questions require new information that bridges the gap in reasoning. This choice just restates what we already know, so it’s not enough.
B. This would help if it said “an action must be either right or wrong.” Instead, it says “if something is wrong, it’s not right,” which is obvious but unhelpful. We need a statement that allows us to infer rightness from the absence of wrongness—this doesn’t do that.
C. Correct. The argument establishes: Decrease in well-being → Wrong.
If an action leaves well-being unchanged, then it didn’t decrease it, so it’s not wrong. This choice adds the missing link: if an action isn’t wrong, it must be right. That’s exactly what we need to prove the conclusion.
D. This merely tells us that actions can leave well-being unchanged. But the argument assumes such actions exist, it’s concerned with what their moral status would be if they do. So this doesn’t advance the reasoning.
E. This brings in the new term “consequences,” which is broader and vaguer than the argument’s focus on aggregate well-being. Since it introduces a different concept, it can’t help support the conclusion.
“Atrens: An early entomologist observed ants carrying particles to neighboring ant colonies and inferred that the ants were bringing food to their neighbors. Further research, however, revealed that the ants were emptying their own colony’s dumping site. Thus, the early entomologist was wrong.”
Atrens’s conclusion follows logically if which one of the following is assumed?
(A) Ant societies do not interact in all the same ways that human societies interact.
(B) There is only weak evidence for the view that ants have the capacity to make use of objects as gifts.
(C) Ant dumping sites do not contain particles that could be used as food.
(D) The ants to whom the particles were brought never carried the particles into their own colonies.
(E) The entomologist cited retracted his conclusion when it was determined that the particles the ants carried came from their dumping site.
Answer:
A. Irrelevant. Similarities between ants and humans don’t tell us anything about whether the ants were transporting food from the dumping site.
B. The stimulus never actually says the early entomologist thought the ants were giving gifts. We don’t know what he believed the purpose of the food transfer was—he may have thought they were trading or doing something else entirely.
C. Correct. If the particles from the dumping site were inedible, then they clearly couldn’t have been food brought to the other nest. This directly supports the argument and rules out the food hypothesis.
D. This one’s a trap. It implies the particles weren’t food because they weren’t used by the other ants, but that’s not conclusive. Maybe the ants consumed the food outside the nest, or maybe they rejected it for another reason. It doesn’t rule out all possibilities.
E. The entomologist’s change of opinion doesn’t prove anything. We need factual support, not speculation about someone’s beliefs. Even if he retracted his original view, he might’ve been right all along.
“Actor: Bertolt Brecht’s plays are not genuinely successful dramas. The roles in Brecht’s plays express such incongruous motives and beliefs that audiences, as well as the actors playing the roles, invariably find it difficult, at best, to discern any of the characters’ personalities. But, for a play to succeed as a drama, audiences must care what happens to at least some of its characters.”
The conclusion of the actor’s argument can be properly drawn if which one of the following is assumed?
(A) An audience that cannot readily discern a character’s personality will not take any interest in that character.
(B) A character’s personality is determined primarily by the motives and beliefs of that character.
(C) The extent to which a play succeeds as a drama is directly proportional to the extent to which the play’s audiences care about its characters.
(D) If the personalities of a play’s characters are not readily discernible by the actors playing the roles, then those personalities are not readily discernible by the play’s audience.
(E) All plays that, unlike Brecht’s plays, have characters with whom audiences empathize succeed as dramas.
Answer:
A. Correct. This directly addresses the logical gap identified in the argument. It provides the missing link needed to make the reasoning work.
B. This just reuses ideas from the same sentence in the stimulus without adding anything new. Be cautious of answers that simply echo familiar terms; they may feel right due to repetition, but they often don't advance the logic.
C. “Directly proportional” is a common trap on the LSAT. It means two variables increase or decrease at exactly the same rate. That level of precision is almost never necessary—or relevant—in these arguments. Think about it: do you really need your LSAT score to increase proportionally to your chances of law school admission?
D. This option introduces a rule about how to write plays in general, but the stimulus is specifically about Brecht’s plays. Since we already know audiences and actors don’t grasp Brecht’s personalities, this broader guideline is irrelevant.
E. This answer gives us: has personality → succeeds. But that structure won’t help us conclude that a play without personality doesn’t succeed. To do that, we’d need a statement like: not succeed → no personality. This answer doesn’t give us what we need.
“The chairperson should not have released the Election Commission’s report to the public, for the chairperson did not consult any other members of the commission about releasing the report before having it released.”
The argument’s conclusion can be properly inferred if which one of the following is assumed?
(A) It would have been permissible for the chairperson to release the commission’s report to the public only if most other members of the commission had first given their consent.
(B) All of the members of the commission had signed the report prior to its release.
(C) The chairperson would not have been justified in releasing the commission’s report if any members of the commission had serious reservations about the report’s content. (D) The chairperson would have been justified in releasing the report only if each of the commission’s members would have agreed to its being released had they been consulted.
(E) Some members of the commission would have preferred that the report not be released to the public.
Answer:
A. Correct. The contrapositive of this statement is: No consent → Not permissible.Since the chairperson didn’t ask for consent, we can’t assume it was given, so the release wasn’t permissible. This fills the logical gap perfectly.
B. This weakens the argument. It doesn’t prove the release was justified, but it suggests the members agreed with the content, which undercuts the conclusion.
C. We don’t know if any members objected, so this doesn’t help. And even if one did, the structure Objection → Permissible doesn’t support the idea that the release was not permissible.
D. This misses the point. It says members might have agreed if asked, but we need something that makes the lack of consultation itself a problem. This doesn’t do that.
E. This doesn’t establish that the release was improper. The stimulus never required unanimous agreement, so individual preferences don’t prove the action was wrong.
“Clearly, a democracy cannot thrive without effective news media. After all, a democracy cannot thrive without an electorate that is knowledgeable about important political issues, and an electorate can be knowledgeable in this way only if it has access to unbiased information about the government.”
The argument’s conclusion is properly inferred if which one of the following is assumed?
(A) All societies that have effective news media are thriving democracies.
(B) If an electorate has access to unbiased information about the government, then that electorate will be knowledgeable about important political issues.
(C) A democracy will thrive if its electorate is knowledgeable about important political issues.
(D) A democracy cannot thrive if the electorate is exposed to biased information about the government.
(E) Without effective news media, an electorate will not have access to unbiased information about the government.
Answer:
A. This reverses the logic. The argument claims that democracies depend on media, but that doesn’t mean media will create democracies. It’s a one-way relationship, and this choice gets it backward.
B. This simply flips one of the argument’s premises and fails to support the conclusion. It doesn't establish that the media is necessary for delivering unbiased information.
C. Again, this reverses a premise without adding anything useful. The fact that a knowledgeable electorate leads to democracy doesn’t help prove that media is required for such an electorate.
D. This is extreme and unrealistic. It implies that any exposure to biased information would doom a democracy, which doesn’t reflect how real-world democracies operate. More importantly, it doesn’t help tie the argument back to the role of media.
E. Correct. This provides the missing link: Unbiased information → Media.This directly supports the argument’s conclusion that the media is necessary for democracy by completing the logical chain.
All actual LSAT® content reproduced within this work is used with the permission of Law School Admission Council, Inc., (LSAC®) Box 40, Newtown, PA 18940, the copyright owner. LSAC does not review or endorse specific test-preparation materials, companies, or services, and inclusion of licensed LSAT Content within this work does not imply the review or endorsement of LSAC. LSAT (including variations) and LSAC are registered trademarks of LSAC.
Reviewed by:
Senior Law School Admissions Advisor & Litigation Attorney, USC Gould School of Law
We're so confident in our 173+ scoring tutors that we'll guarantee you get a 165+ on the LSAT, or you'll get more tutoring for free. Win-win.
