How to approach the LSAT Logical Reasoning section

How to approach the LSAT Logical Reasoning section

The takeaways
  • Arguments are composed of a premise(s), support, and conclusion. Arguments are strengthened by support and weakened by assumptions.
  • Avoid letting outside influences affect your comprehension of the LSAT stimulus.
  • Every sentence has a structural purpose — question which element(s) a sentence is supported by and supports in turn.

Intro to Logical Reasoning

This blog focuses on providing a breakdown of the Logical Reasoning (LR) section and a high-level systematic approach for answering LR questions. When approaching the LSAT, we want to be as systematic as possible with how we answer the questions  — developing a system will allow us to repeat our success. 

Table of Contents:

  • LR section breakdown
  • What is an argument?
  • What makes a good argument? Support and Assumptions
  • What is support?
  • What are assumptions?
  • 5-Step Systematic Approach to LR

LR Section Breakdown

The logical reasoning section, post-August-2024, is the most important section in the exam. It was also the most important section in the LSAT before the flex-LSAT in 2020, where the LSAT was scored with one analytical reasoning section, one reading comprehension section, and two logical reasoning sections.

LR is designed to test two primary skills: reading and reasoning. Learning how to actively read, both accurately and efficiently, and interpreting what a statement is trying to convey is a crucial skill in the world of logic and will apply both to the LR and RC sections. Your reasoning skills will be tested in the LR section as well, which is your ability to discern how and why an argument works or doesn't work by identifying the logical structure.

What is an argument?

Every argument on the LSAT will consist of three primary things. 

1. Premise(s) (“P”)

2. Conclusion (“MC” or “C”)* sometimes referred to as a “main point” in the LSAT

3. Support (the relationship between P→C)

On the LSAT, we will accept P’s as true statements in the argument. On the other hand,we will always question the truth and validity of the MC in relation to the support of the P’s. It is important to note that both P and MC are sentences you can directly pick out in the stimulus, whereas the “support” of the argument only exists as an abstract relationship between the two statements P←→C.

Here is an example argument:

(A) Wendy has never missed a day of work. 

(B) Wendy should get a pay raise.

Can you pick out which sentence A or B, is the premise and conclusion of this argument?

If you determined that the logical flow is Premise A → Conclusion B, then you’d be correct! 

One way we can verify that statement A is indeed the premise and statement B is the conclusion is to ask ourselves which sentence provides support to the other sentence. As in, which sentence, if true as a premise (which, in the LSAT, we must accept premises as true!) will help prove the other sentence is more likely to be true?

Accept (A) as true = Wendy indeed has never missed a day of work.

Does that mean we should be more likely to accept that (B) Wendy should get a pay raise?

The conclusion (Wendy should get a pay raise) isn’t automatically proven by the premise; we’re asking whether accepting the premise (Wendy has never missed a day of work) as true makes the conclusion more convincing. The world of law and arguing is to convince other people to concede to your argument, after all!

Okay, what about if we mistakenly made sentence (A) as the conclusion? Let’s do the same thing but reverse the statements! Let’s assume (B) is the premise. So (B) Wendy should get a raise, and because Wendy should get a raise, we should also be more likely to believe that (A) she has never missed a day of work.

That sounds weird and off because it is. The logical flow of this argument is statement A flowing support → Statement B.

This is what we will refer to as the flow of support. 

The flow of support is the direction in which the premise(s) directionally point toward the argument’s conclusion.

As you read more and more LR stimuli, with each sentence, you can ask yourself — what does this statement support? Is this statement flowing to support another statement (premise), or is it the end of the river, receiving the flows of support (conclusion)?

The LR section has many complex argument structures. The conclusion is not always the last sentence:the conclusion can be the first statement, somewhere in the middle, or the final statement. There will often be more than one premise which  may be layered themselves and have sub-conclusions. Also a premise could support another premise which in turn,supports the main conclusion of the argument. Although the arguments will only get more complex from here after we’re done arguing for Wendy’s pay raise, do remember that the foundational building blocks of logical arguments in both the real world and the LSAT are made up of premises, conclusion, and support.

What makes a good argument? Support and Assumptions.

So what makes a good argument? How do we make a convincing argument in the world of law, and how do we criticize other people’s arguments? Well, there are two components to what makes an argument “good” or “bad” in the LSAT world, and that is the support and assumptions made. The LSAT writers will very often make us play around these two variables, so having a strong understanding of how they affect (or don’t affect) an argument is key.

  1. Support (from premises)
  2. Assumptions (within the context of the LSAT, and external or outside assumptions).

What is support?

Support is the degree to which the likelihood of a statement’s truth is increased. “Support” operations in the LSAT can be positive, neutral, or negative .

Does premise A support statement B? Good support means we are more likely to believe in the conclusion (Wendy never missing work → maybe get a raise).

Some statements can have neutral support, in this case, it’d be irrelevant to the argument. Some statements will go the opposite way of support and instead weaken the conclusion (“weakening” is a type of LR stem!).

When reading statements within an argument, being cognizant of the flow of support can help us pinpoint where the conclusion might be in the stimulus.

What are assumptions?

On the LSAT, it’s incredibly important to understand exactly what you are reading without making outside assumptions.

What is an assumption? It is something that we accept as true while lacking substantial proof.

In the LSAT world, we want to try our best to limit our outside-world assumptions as much as possible, barring very reasonable assumptions. The questions on the LSAT, although often working with broad and dense topics, are intended to be answerable by laymen. Any specialized jargon will either be explained or is not necessary to understand to answer the question. We never fill in major assumptions for the LSAT authors. 

Therefore, arguments that depend on assumptions are never “valid” or 100% true. 

They are simply stronger or weaker, depending on the assumptions, which can be very obvious or in many cases, very subtle. In this way, we can divide the LR questions into two camps, “assumptions” and “descriptive.” 

Here are some examples of P → C flows. Can you point out the assumptions made in each mini-argument and conclusion? These mini-arguments can all have more than one assumption made to help the conclusion, some of them more reasonable than others. Assumptions can also be very sneaky, 

  1. Wendy is taller than David → Wendy is tall
  2. Lions are wild carnivorous animals that are not domesticated and can therefore harm people → Lions cannot be pets
  3. Tim has 20+ years of experience as an attorney and argues that X did commit the crime → we should trust Tim’s judgment
  4. Peter has never gotten a bad review in his work → Peter should get a raise
  5. Jeff placed 2nd in his powerlifting competition → Jeff must be really strong

Assumptions below:

  1. You assume that David is also “tall.” What if David is actually a 10-year-old kid who hasn’t hit his growth spurt yet? How can we conclude Wendy is tall simply by being taller than a 10-year-old?
  2. It might seem reasonable, based on our understanding of the world, that a large beast that can harm us probably isn’t a good pet. But I’m sure we’ve all seen some video of an Australian park ranger cuddling with his furry beast! The assumption made here is that being a wild carnivorous animal, and the ability to harm people, therefore makes it impossible to be a “pet.”
  3. We assume many things about Tim’s character here! The major one is that experience = competency of judgment. Some more outlandish assumptions might be that we also assume that Tim isn’t being paid under the table to lie about his judgment, that Tim has sufficient evidence, and that his experience in law is even in the realm of criminal law! For all we know, maybe he’s just a tax attorney (albeit a great one).
  4. Not getting a bad review = a reason for getting a raise. Maybe Peter also has never gotten a good review for his work either. Maybe he’s perfectly neutral and being paid fairly. Maybe the company doesn’t even offer reviews!
  5. We assume that the competition that Jeff competed in had more than 2 people. Placing 2nd among thousands of contestants might be a good reason to prove that Jeff is quite strong. Placing 2nd among two people means he is technically last; although not completely disproving he’s not strong. Maybe he competed against the world’s strongest person.

Do you see how easy it is really when we build out the world of assumptions, that can add doubt to the conclusion of any argument?

Now, none of these assumptions are true (or untrue); they are simply possibilities, and thus things we need to be wary of and not to make assumptions in our arguments while being cognisant of the LSAT writer’s traps.

Assumptions and support have an inverse relationship towards making an argument “good.”

More support = “better” the argument.

More assumptions = “worse” the argument.

There are many different types of arguments in the LSAT, including conclusions that depend on formal logic and are reasonably sound with no assumptions made, to the more abstract, inferential flaw-based questions. Ultimately, how likely we should feel convinced of an argument, and therefore accept it as a “good” argument, fluctuates as a function of these two variables: support and assumptions. As mentioned earlier, the LSAT writers will very often make you play around these two variables, so having a strong understanding of how they affect (or don’t affect) an argument is key. Understanding that they exist is the first and very important step to tackling the LR section!

Next, let’s move on to how to approach LR questions in general.

5-Step Systematic Approach to Answering Logical Reasoning Questions

  1. Question Stem
  2. Active Read Stimulus
  3. Identify Argument Structure & Stimulus Components
  4. Analyze Stimulus
  5. Evaluate Answers

Okay, so what does each step mean here?

  1. Question Stem:
    1. What question are we dealing with here? (AdeptLR has subdivided logical reasoning questions into 17 types)
  2. Active Read Stimulus:
    1. What are we even talking about here? Did you understand what you just read? A good way to know if you truly understood what you just read is to ask yourself —  can I translate this into my own words? 
  3. Identify Argument Structure & Stimulus Components:
    1. What is the argument, if there is one?
    2. What is the logical structure of the argument?
    3. Where is the main conclusion, premises, sub-conclusions, order/parts, etc.
    4. Identifying MC through the flow of support
  4. Analyze Stimulus:
    1. Determine support and assumptions.
    2. Depending on the question type, how you analyze the stimulus will have a different approach. 
    3. AdeptLR has articles on the analysis of LR question sub-types
  5. Evaluate Answers Pass-through:
    1. Process-of-elimination (POE)
    2. Predicting answers

This article taught us the basics of the LR section and the components of arguments. We also went into how to actively read a stimulus and how to identify the flow of support to arrive from P → C from the 5-step systematic approach to LR questions (steps 2 and 3). In our “Approach Series,” there will be more in-depth articles on how to analyze the 17 different LR questions (step 4).

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