LSAT Sufficient Assumption Questions: Be the D.A. for the Day!

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Manhattan Prep LSAT Blog - LSAT Sufficient Assumption Questions: Be the D.A. for the Day! by Patrick Tyrrell

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Congratulations, you are the District Attorney… til about 5:45 or 6:00 p.m. Thanks to a new law that voters moronically passed via referendum last April, the role of District Attorney will cycle through local citizens, much as it does with jury duty. Today, it’s your turn to try to win some convictions.

In a sense, that should be our mentality when we do LSAT Sufficient Assumption questions (or Principle Support questions). The other questions in the Assumption Family (Necessary Assumption, Flaw, Strengthen, Weaken, Evaluate) are more about playing Opposing Counsel, hearing the author’s argument and thinking about how we would respond.

LSAT Sufficient Assumption questions and Principle Support questions assign us a more proactive task: Win the Case, i.e., prove the Conclusion.

LSAT Sufficient Assumption Questions
Which answer, if assumed, would allow the conclusion to follow logically / be properly drawn / properly inferred?

Principle Support Questions
Which answer, if valid, would most justify the conclusion?

Principle Support doesn’t actually require that we prove the conclusion, but most correct answers nonetheless do prove it. For both question types, we are looking for an answer choice that would combine with the evidence the author presented and allow us to derive the author’s conclusion.

The Argument Core, “Premises —leading-to–> Conclusion,” is essentially “Evidence —leading-to–> Verdict.”

In a court case, the judge is thinking, “Given this evidence, has the prosecutor convinced me of the guilty verdict?” With arguments, LSAT students are thinking, “Given this evidence, has the author convinced me of the conclusion?”

Suppose we had a conclusion that really sounded like a verdict: “Therefore, Gus is guilty of grand larceny.” We are trying to prove that Gus committed grand larceny. If you were the D.A. in charge of prosecuting this case, what’s the first thing you would do or ask?

If it were me, I would ask someone (discreetly), “I mean, I know what grand larceny is… obviously… I’m the D.A., no big deal… but just so everyone else here knows what grand larceny is… can you please define grand larceny?”

[Patrick tabs over to his browser and searches for the definition of grand larceny] Apparently, although it varies from state to state, grand larceny normally means “you stole property that was worth at least $400.”

Okay, we think, I’ve got this. Being a District Attorney is easy, and if we’re being honest… I look good doing it. Now that I’ve looked up the relevant statute, I know that to win this verdict I’ll have to convince the judge that Gus stole something worth at least $400. What kind of evidence do we have?

“Well,” your paralegal says, “we found this upright piano in the back of Gus’s van.”

Looking at that evidence, and remembering that the definition of grand larceny is stealing property worth at least $400, what is our job in court? What do we have to establish so that the judge will be convinced that grand larceny is a proper verdict?

We need to establish two things:

  1. Gus stole the piano.
  2. The piano is worth at least $400.

If we can establish those facts, then we win the case, because we will have shown that the present situation conforms to the letter of the law.

If this court case were an LSAT Sufficient Assumption question, the test writers could test us on it in several different ways:

In the back of Gus’s van, officers found an upright piano worth about $800.
Since Gus stole this piano, he is guilty of grand larceny.

Which of the following, if assumed, would allow the conclusion to follow logically?

(A) If you steal something worth at least $400 in value, you have committed grand larceny.

Gus is guilty of grand larceny. After all, grand larceny is theft of property worth at least $400 and the piano found in the back of Gus’s van was worth about $800.

Which of the following, if assumed, would allow the conclusion to follow logically?

(A) Gus stole the piano in his van.

Grand larceny is defined as the act of stealing property worth at least $400 in value. Thus, Gus is clearly guilty of such a charge, given that late last night, police found in Gus’s van the piano that he had stolen.

Which of the following, if assumed, would allow the conclusion to follow logically?

(A) The piano was worth at least $400.

Notice that in the first example we had, all the necessary facts about Gus lacked the relevant definition of grand larceny. In the second and third example, we had the definition but had still not established one of the definition’s two components.

When I’m doing LSAT Sufficient Assumption questions, my process is usually something like this:

1. Read the paragraph, primarily for the sake of finding the Conclusion.

LSAT Sufficient Assumption questions are great about giving us Conclusion keywords (so, thus, therefore, hence) or Premise keywords (for, after all, because, since) to make it easy to visually find the conclusion.

2. Think about the Conclusion as the verdict I’m trying to prove and ask, “Do I have a legal definition for this idea?”

f.e. if the conclusion is something like “Thus, Clara’s milk spill is not truly art,” then my first question to myself is, “Do I have a legal definition for what makes something truly art or not?”

3a. If I don’t have the definition, then I know that the correct answer needs to provide me with the definition.

The correct answer needs to be a law that lets me prove that something is not truly art, so I would consider answers that translate into “if _____, then not truly art,” and I would immediately reject answers that translate into “if ____, then truly art,” as well as reject any answers that don’t mention the term “truly art.”

3b. If I do have a definition, then I re-read the Evidence and think, “What part of this definition have we failed to trigger so far, with the provided facts?”

In the 2nd and 3rd grand larceny examples above, we had a definition for grand larceny that required establishing two ideas, so we were reading the evidence asking, “Have I definitively established that Gus stole this piano and that this piano was worth at least $400?”

APPLYING THIS TECHNIQUE TO PREP TEST 8

In PT83, Section 1, Q9, we get a Principle Support question and (1) the conclusion we’re trying to prove is “Don’t request a replacement for Ted.” I would ask myself (2), do I have a rule for how I know when I should or shouldn’t request a replacement? I don’t (3a), so the correct answer needs to give me a rule that translates into “if ___, then don’t request a replacement.” That eliminates choices (B), (D), and (E) very easily, since none of them deal with whether or not we should request a replacement.

In PT83, Section 1, Q20, we get a Principle Support question and (1) the conclusion we’re trying to prove is that “we understand X better than Y.”  I would ask myself (2), do I have a rule for how I know whether we understand one thing better than another? I don’t (3a), so the correct answer needs to give me a rule that translates into “if ___, then I understand X better than Y.” That eliminates choices (A), (C), and (E) very easily (they don’t mention “better understand” at all).

In PT83, Section 3, Q13, we get an LSAT Sufficient Assumption question and (1) the conclusion we’re trying to prove is that “something is not physical phenomena.” I would ask myself (2) do I have a rule for how I know whether something is or isn’t a physical phenomenon? I don’t (3a), so the correct answer needs to give me a rule that translates into “if ___, then it’s not a physical phenomena.” That eliminates choices (B) and (C) very quickly, since they don’t even mention ‘physical phenomena.’ (A) and (D) can be eliminated with more scrutiny, since they translate into “if not physical phenomena, then ______.” I need a rule that PROVES something is not a physical phenomenon, so the idea of “not physical phenomena” has to be the right side of the rule.

In PT83, Section 3, Q19, we get a Principle Support question and (1) the conclusion we’re trying to prove is that “the bill should be rejected.” I would ask myself (2) do I have a rule for how I know whether a bill should or shouldn’t be rejected? I don’t (3a), so the correct answer needs to give me a rule that translates into “if ___, then should be rejected.” These answers aren’t as easy to quickly diagnose, but (C), (D), and (E) give us potentially usable rules.

(C) “If ______, then don’t implement this proposed solution.” (we should reject this bill)
(D) “If _____, then don’t use this law.” (we should reject this bill)
(E) “If _____, then don’t implement this policy.” (we should reject this bill)

Happy studying! 📝


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patrick-tyrrellPatrick Tyrrell is a Manhattan Prep instructor based in Los Angeles, California. He has a B.A. in philosophy, a 178 on the LSAT, and relentless enthusiasm for his work. In addition to teaching test prep since 2006, he’s also an avid songwriter/musician. Check out Patrick’s upcoming LSAT courses here!

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