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Assumption questions are a common and tricky part of the LSAT. But with the right approach, they can become predictable and easy to solve!
Assumption questions ask you to identify an unstated premise that the argument depends on, something that must be true for the conclusion to logically follow from the evidence.
In other words, the correct answer fills a gap between the argument’s evidence and its conclusion. These questions test your ability to spot what the author is taking for granted, and they often reward clear, precise reasoning over surface-level logic.
You can recognize Assumption questions by keywords in the question stem, such as:
All LSAT assumption questions fall into one of two types: necessary or sufficient. Necessary assumption questions ask what must be true for the argument to work, while sufficient assumption questions ask what, if true, would make the argument fully valid.
Once you’ve identified the question type, start by breaking down the argument: pinpoint the conclusion and the supporting evidence. Then, look for the logical gap; ask yourself, “What must be true for this evidence to support the conclusion?” This gap points directly to the assumption.
A powerful tool at this stage is the Negation Test: for necessary assumption questions, try negating each answer choice. If negating it weakens or destroys the argument, that’s a strong sign it’s the correct answer.
Be cautious of extreme language. Assumptions are usually more moderate in tone. The correct choice is something the argument quietly relies on, not a bold or sweeping claim. On test day, sticking to this method gives you a clear plan of attack and helps you stay focused and efficient, even under pressure.
Here are 10 sample Assumption questions with a detailed explanation for each answer.
“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 provides sufficient conditions for board eligibility. Its contrapositive is: not eligible for board → no master’s degree or felony conviction. That’s unhelpful; it simply confirms that if someone isn’t eligible, it could be due to either reason. Since we already know Murray has a felony, this adds nothing new.
B. Correct. If this statement is true, it links eligibility for Executive Administrator to eligibility for the board. Given Murray can’t be on the board due to his conviction, he also can't be Executive Administrator.
C. The diagram here is: Executive Administrator eligibility → board eligibility and it only tells us that if someone is eligible to be Executive Administrator, they must also be eligible for the board. Murray isn’t eligible for the board, but that doesn’t definitively rule him out from being Executive Administrator unless the conditional flows the other way.
D. This reflects a flawed logical negation. Just because having a felony isn’t necessarily disqualifying doesn’t mean it’s never disqualifying. The conclusion still could hold true, but this doesn't prove or disprove it.
E. Again, this doesn’t establish the felony as an absolute disqualifier for the Executive Administrator role. It’s possible Murray would be ineligible regardless. So this answer fails to support the conclusion.
“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 discusses the future use of aluminum, while the argument is about its past origin. It’s irrelevant to the conclusion.
B. The quality of the aluminum isn’t at issue. The argument focuses solely on the number of cans, not how good the aluminum is. Even if low-quality aluminum couldn’t be reused, this answer doesn’t say that.
C. Correct. This directly supports the argument. Since all the cans from group L were used to make cans in group M, and those accounted for half the aluminum in M, group M must have had twice as many cans as L. The source of L’s aluminum doesn’t matter; only where it ended up does.
D. This is a much weaker version of C. While C confirms the argument with certainty, this only suggests a possibility. It doesn’t guarantee the conclusion is true.
E. This answer shifts focus to metal types and potential aluminum savings, which doesn’t help prove or disprove the argument about the can counts. It’s off-topic.
“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 is irrelevant. The argument focuses on whether it's necessary to vaccinate everyone or just a subset of the population.
B. This point concerns the likelihood of an epidemic. However, severe flu cases can still occur even when there's no epidemic, so this doesn't directly address the conclusion.
C. Be cautious here. The passage clearly states that the program uses vaccines that protect against only one strain. Whether other vaccines can cover multiple strains is irrelevant, since those aren't being used in the program.
D. Correct. If true, this supports the idea that vaccines lose effectiveness each year due to changing strains. That means high-risk individuals would need to be vaccinated annually, reinforcing the conclusion.
E. Side effects are not a concern here. The argument assumes that protecting high-risk individuals is a priority, likely because any side effects are minimal or considered acceptable.
“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 states that "wrong" is a necessary condition for actions that reduce aggregate well-being. This answer just repeats that and doesn't provide new support. Since sufficient assumption questions require new information that guarantees the conclusion, this can’t be correct.
B. If the answer had said, “An action must be either right or wrong,” it would have helped. Instead, it says, “If something is wrong, it's not right.” That doesn't move the argument forward. What we need is a statement like, “If something is not wrong, then it is right.”
C. Correct. The reasoning in the stimulus tells us that reducing well-being implies an action is wrong. So if an action leaves well-being unchanged, it's not wrong. This answer adds that if something is not wrong, then it is right—exactly what’s needed to complete the logic and support the conclusion.
D. This option tells us that actions leaving well-being unchanged do exist, but that’s not relevant. The argument is about what follows if such actions exist, not whether they actually do. For example, saying “you’ll be wealthy if you win the lottery” doesn't require that you win—it’s about the conditional outcome.
E. This choice introduces the term “consequences,” which doesn’t appear in the original argument. Since it's broader than the concept of affecting well-being, it can't help connect the existing premises to 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. This is irrelevant. Similarities between ants and humans have no bearing on whether ants were actually transporting food from the dumping site.
B. The stimulus doesn’t mention gifts or motives. We don’t know why the early entomologist believed the ants were carrying food. It could’ve been for trade, sharing, or something else entirely.
C. Correct. If the particles from the dumping site were unsuitable as food, they couldn’t have been food deliveries to the other nest. This directly supports the conclusion.
D. This is misleading. Just because the receiving ants didn’t use the particles doesn’t prove they weren’t food. They could have eaten them elsewhere, or simply rejected them. This doesn’t rule out all possibilities.
E. The entomologist’s belief, or later retraction, is irrelevant to the facts. People retract correct claims all the time. What matters is the evidence, not what someone believed.
“Naturalist: The recent claims that the Tasmanian tiger is not extinct are false. The Tasmanian tiger’s natural habitat was taken over by sheep farming decades ago, resulting in the animal’s systematic elimination from the area. Since then naturalists working in the region have discovered no hard evidence of its survival, such as carcasses or tracks. In spite of alleged sightings of the animal, the Tasmanian tiger no longer exists.”
Which one of the following is an assumption on which the naturalist’s argument depends?
(A) Sheep farming drove the last Tasmanian tigers to starvation by chasing them from their natural habitat.
(B) Some scavengers in Tasmania are capable of destroying tiger carcasses without a trace.
(C) Every naturalist working in the Tasmanian tiger’s natural habitat has looked systematically for evidence of the tiger’s survival.
(D) The Tasmanian tiger did not move and adapt to a different region in response to the loss of habitat.
(E) Those who have reported sightings of the Tasmanian tiger are not experienced naturalists.
Answer
A. The exact cause of the last tiger’s extinction isn’t the point. What matters is that sheep farming significantly contributed. Even if hunters killed the last few, that wouldn’t weaken the argument.
B. If true, this weakens the argument. The presence of tiger carcasses would imply recent survival, but scavengers removing them could explain why none were found.
C. Negating this has no meaningful effect. One naturalist failing to look, regardless of the reason, doesn’t change the overall picture.
D. Correct. If this isn’t true, if the tigers relocated and survived elsewhere, it directly undermines the claim that sheep farming caused their extinction.
E. This might slightly support the argument, but it’s not critical. Like C, the opinion of a single naturalist (especially one impaired) doesn’t significantly affect the conclusion.
“When exercising the muscles in one’s back, it is important, in order to maintain a healthy back, to exercise the muscles on opposite sides of the spine equally. After all, balanced muscle development is needed to maintain a healthy back, since the muscles on opposite sides of the spine must pull equally in opposing directions to keep the back in proper alignment and protect the spine.”
Which one of the following is an assumption required by the argument?
(A) Muscles on opposite sides of the spine that are equally well developed will be enough to keep the back in proper alignment.
(B) Exercising the muscles on opposite sides of the spine unequally tends to lead to unbalanced muscle development.
(C) Provided that one exercises the muscles on opposite sides of the spine equally, one will have a generally healthy back.
(D) If the muscles on opposite sides of the spine are exercised unequally, one’s back will be irreparably damaged.
(E) One should exercise daily to ensure that the muscles on opposite sides of the spine keep the back in proper alignment.
Answer
A. The author is not claiming that equal exercise is enough to align the back, only that it is important. Other factors may also be involved, so this does not weaken the argument.
B. Correct. If this is false, the conclusion loses its support. If uneven exercise does not lead to muscle imbalance, then the main claim falls apart.
C. Like A, this misses the point. The argument says equal exercise is important, not that it is the only thing needed for a healthy back.
D. This statement goes too far. Taken literally, it suggests even one mistake causes permanent harm, which is unrealistic. The argument does not rely on such an extreme claim.
E. The argument never says how often you must exercise. It is possible to maintain a healthy back with exercise every other day, so this has no impact on the conclusion.
“Editorial: The city has chosen a contractor to upgrade the heating systems in public buildings. Only 40 percent of the technicians employed by this contractor are certified by the Heating Technicians Association. So the city selected a contractor 60 percent of whose technicians are unqualified, which is an outrage.”
Which one of the following is an assumption required by the argument in the editorial?
(A) Certified technicians receive higher pay than uncertified technicians.
(B) There are no contractors with fewer than 40 percent of their technicians certified.
(C) Technicians who lack certification are not qualified technicians.
(D) Qualified technicians installed the heating systems to be upgraded.
(E) The contractor hired by the city has personal ties to city officials.
Answer
A. Pay is irrelevant here. The argument does not mention salary at all.
Negation: Certified technicians do not earn more than uncertified ones. Still irrelevant to the issue of qualification.
B. It does not matter if some other contractors are worse. What matters is whether others have more certified technicians, which could challenge the original claim.
Negation: One contractor in Ecuador has 39 percent certified technicians, while every other contractor worldwide has 40 percent. This doesn’t help the argument.
C. Correct. This directly challenges the argument’s logic. The author assumes certification equals qualification without justifying the link.
Negation: Technicians can be qualified even if they are not certified. If this is true, the argument falls apart.
D. Who installed the systems in the past does not matter. The question is about whether current technicians are qualified.
Negation: The heating system was installed by trained monkeys. Still irrelevant.
E. Potential conflicts of interest are not the issue. The argument is only concerned with technician qualifications.
Negation: The contractor has no personal ties to any city officials. This changes nothing.
“Biologist: Marine animals known as box jellyfish have eyes with well-formed lenses capable of producing sharp images that reveal fine detail. But the box jellyfish’s retinas are too far forward to receive a clear image, so these jellyfish can receive only a blurry image that reveals prominent features of objects but not fine detail. This example shows that eyes are adapted only to an animal’s needs rather than to some abstract sense of how a good eye would be designed.”
The argument requires assuming which one of the following?
(A) Box jellyfish are the only kind of jellyfish with retinas that do not focus clearly.
(B) Box jellyfish have a need to detect prominent features of objects but not fine details.
(C) Box jellyfish would benefit from having retinas that allowed their eyes to focus more sharply.
(D) Box jellyfish developed from jellyfish whose retinas received clear images.
(E) Box jellyfish use vision as their main means of detecting prey.
Answer
A. What other jellyfish can or cannot do is irrelevant. The argument is focused specifically on box jellyfish.
Negation: One other type of jellyfish cannot focus clearly. This has no bearing on the conclusion.
B. Correct. The conclusion is about what box jellyfish need, but the argument never established what those needs actually are. This answer fills that gap.
Negation: Box jellyfish need to detect fine details. If this is true, the argument's conclusion is undermined.
C. This assumption would weaken the argument. The author suggests box jellyfish do not need better vision, which is why they have good eyes that seem to serve no clear purpose.
Negation: Box jellyfish would not benefit from better vision. Rather than weakening, this actually supports the conclusion, which is not what a proper negation should do.
D. This introduces unnecessary confusion. If their ancestors had better vision, we would need an explanation for why that ability was lost. Evolutionary backtracking raises more questions than it answers in this context.
E. Whether box jellyfish have other ways to detect things is beside the point. The argument is about whether they need better vision, regardless of other sensory tools.
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. If audiences cannot understand a character’s personality, they will not care about that character. This directly supports the argument’s claim that Brecht’s plays cannot succeed as dramas.
B. This explains what makes up a personality, but the argument does not depend on that. It only matters that audiences cannot recognize the personalities, not how they are formed.
C. Saying success is "directly proportional" to audience interest adds unnecessary precision. The argument only requires that caring is needed, not that it increases success in exact amounts.
D. This just repeats part of the passage, which already states that both actors and audiences struggle to understand the characters. It does not add anything useful to support the conclusion.
E. This shifts focus to other plays and how they succeed, which is irrelevant. The argument is only about why Brecht’s plays fail as dramas.
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Reviewed by:
Senior Law School Admissions Advisor & Litigation Attorney, USC Gould School of Law
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