lsat logical reasoning 101

ESSENTIAL TIPS AND INFORMATION

Two of the four scored sections of your LSAT will be Logical Reasoning, and Logical Reasoning questions account for roughly half of your overall score. Logical Reasoning questions lie at the heart of what the LSAT is all about, and they are the most important types of questions for you to master. Whether you are just starting your LSAT prep, or you've been at it for a while, you've come to the right place. In this brief article, we will discuss basic details about Logical Reasoning problems, look at a couple of sample questions together, highlight effective practice methods, and more. Let's get started.

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Basic Details About Logical Reasoning

  • Two of your four scored sections will be Logical Reasoning sections.
  • Recently, all Logical Reasoning sections have had either twenty-five or twenty-six  total questions.
  • Twenty-five questions in thirty-five minutes works out to about 1:20 per problem. However, keep in mind certain questions should take less time, and others are designed to take more.
  • Each question consists of a stimulus (or prompt), a question stem, and five answer choices.
  • The stimulus will typically be two to three sentences in length.
  • Each question will have one clearly correct right answer and four clearly incorrect wrong answers.
  • A significant majority of problems will require us to evaluate arguments—relationships between points made and support given.
  • About two thirds of all questions require us to evaluate these arguments critically—to consider why the support given does not justify the conclusion reached.
  • About one third of all questions require an objective approach from the test taker. These questions require no evaluation of reasoning and are primarily designed to test our reading abilities.
  • On average and in general, the difficulty of problems increases as the section progresses. However, the difficulty can also fluctuate significantly throughout a section.
  • The average test taker gets anywhere from ten to twelve wrong per twenty-five-question section.
  • A 170+ test taker will consistently get anywhere from zero to three wrong per twenty-five question section.

Two Sample Problems

Here are two sample Logical Reasoning questions, along with explanations for them. The explanations come right after the questions, so if you want to try them without finding out the right answer, be careful not to peek!

(All actual LSAT content used within this work are used with the permission of Law School Admission Council, Inc., Box 2000, Newtown, PA 18940, the copyright owner.  LSAC does not review or endorse specific test preparation materials or services and inclusion of LSAC content within this work does not imply the endorsement of LSAC.  LSAT is a registered trademark of LSAC.)

Question #1

 

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.

 

Atren’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) And 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.

 

June '07 Exam, Section 3, Question 5

Explanation

 

Our Task:

We are asked to identify an answer that allows the conclusion to follow logically. What that means is that we need an answer choice that, when added to the given argument, completely fills any existing reasoning gaps that exist between the author’s conclusion and the given support.

 

The Stimulus:

Atren’s point is that the early entomologists were wrong. What were they wrong about? They claimed that ants were bringing food to their neighbors. Thus, Atren’s point is that the ants do not bring food to their neighbors.

 

What information does Atrens use to support that claim? Research has revealed that, in bringing particles to neighboring colonies, ants are emptying their dumping sites—essentially, getting rid of their own trash.

 

What’s wrong with Atren’s reasoning? If we take the support as being true, does it guarantee the truth of the conclusion? That is, if we know they are giving their neighbors their own trash, do we know for sure that they are not giving their neighbors food?

 

No, we don’t.

 

Per the information we’ve been given, trash and food are not mutually exclusive. The support doesn’t actually tell us that what they give to their neighbors isn’t food, and what we need is an answer choice that addresses this gap.

 

The Answer Choices:

Again, what we are looking for is an answer choice that addresses the reasoning gap between the given support and the author’s conclusion, thereby guaranteeing the truth of the author’s conclusion. The right answer will do just that, and the four answers will not.

 

(A) discusses similarities between ant and human societies — this does not help us bridge the gap between trash and food and (A) is incorrect.

(B) discusses using objects as gifts, which does not directly relate to the author’s conclusion or her support. The fact that there is “weak” evidence also doesn’t directly relate to our task at hand, and so we can eliminate (B) as well.

(C) addresses the gap between trash and food. If the items the ants take from their dumping grounds doesn’t contain any food, we can connect this with the given support (that they are getting the particles to give from the dumping site) and we can know with certainty that they are not delivering any food to their neighbors. (C) is the correct answer.

(D) discusses whether the recipients ever carried the particles into their own colonies—this does not directly impact the author’s conclusion, which is specifically about the ants who bring the particles, and thus (D) is incorrect.

(E) discusses the actions of the entomologist who originally made the claim the author disagrees with — these actions do not help guarantee the truth of the author’s conclusion and (E) is incorrect as well.

 

(Would you like to see a video explanation of this question? Check out the video above; the explanation for this particular problem begins at about the 5:30 mark.)

Question #2

 

Ethicist: The most advanced kind of moral motivation is based solely on abstract principles. This form of motivation is in contrast with calculated self-interest or the desire to adhere to societal norms and conventions.

 

The actions of which of the following individuals exhibit the most advanced kind of moral motivation, as described by the ethicist?

 

(A) Bobby contributed money to a local charity during a charity drive at work because he worried that not doing so would make him look stingy.

(B) West contributed money to a local charity during a charity drive at work because he believed that doing so would improve his employer’s opinion of him.

(C) Donna’s employers engaged in an illegal but profitable practice that caused serious damage to the environment. Donna did not report this practice to the authorities, out of fear that her employers would retaliate against her.

(D) Jadine’s employers engaged in an illegal but profitable practice that caused serious damage to the environment. Jadine reported this practice to the authorities out of a belief that protecting the environment is always more important than monetary profit.

(E) Leigh’s employers engaged in an illegal but profitable practice that caused serious damage to the environment. Leigh reported this practice to the authorities only because several colleagues had been pressuring her to do so.

 

June '07 Exam, Section 2, Question 7

Explanation

 

Our Task:

We are asked to pick an action that best represents “the most advanced kind of moral motivation,” as described the ethicist. So we want to make sure to understand the ethicist’s definition as clearly and correctly as possible, and we should expect to find four answers that clearly do not match this description, and the one correct answer that clearly does.

 

The Stimulus:

The ethicist offers two characteristics of “the most advanced kind of moral motivation”:

1) It is based solely on abstract principles.

2) It is in contrast to calculated self-interest or the desire to adhere to societal norms and conventions.

 

The Answer Choices:

We want to look for an answer that fits the above characteristics, and we want to use the above characteristics to eliminate incorrect answer choices.

 

(A) describes an action taken in order to not appear stingy. This action is not based on abstract principles, and it’s done for his calculated self-interest. Thus (A) is incorrect.

(B) describes an action taken in order to make a good impression. This action is not based on abstract principles, and it’s also done for calculated self-interest, and so (B) is incorrect as well.

(C) describes an action, or a lack of action, caused by fear. Fear is not an abstract principle, and Donna is working in her own self-interest. Thus (C) is incorrect.

(D) describes an action done based on a belief, or abstract principle—that protecting the environment is always more important than monetary profit. Furthermore, there is no evidence that Jadine’s actions were driven by self-interest or a desire to adhere to societal norms and conventions. Thus, (D) is the correct answer.

(E) describes an action done based on receiving pressure from one’s colleagues. Thus her actions are not taken based on abstract principles, and you could argue that her actions are based on self-interest or the desire to adhere to societal norms and conventions. Thus (E) is also incorrect.

 

(Would you like to see a video explanation of this question? Check out the video above; the explanation for this particular problem begins at about the 15:36 mark.)

 

Where Can I Find Additional Practice Problems and How Should I Use Them?

LSAC, the organization responsible for the LSAT, offers one free sample test on their website, and they also offer additional practice exams for sale.

All of the tests LSAC offers are previously administered official exams.

The exams come in bundles of ten (which are known as the "10 Actuals") and as individual tests. The 10 Actuals offer a much better value and are the best choice for most students.

Please click on any of the links below to access the free sample exam offered by LSAC and the prep tests LSAC offers for sale on Amazon.

Links to Practice Problems

Free Practice Offered By LSAC (All from the June '07 exam)

 

"10 Actuals" Books For Sale on Amazon

 

You can also purchase individual practice tests on the LSAC Amazon page.

Tips on Drilling, Practice Sections, and Practice Exams

The three most common ways in which students utilize the practice problems is by drilling, taking full sections, and taking full exams.

Drilling typically involves grouping together and solving questions that relate to one another. Most commonly, this involves solving questions that share a common question stem. For example, a student may drill a collection of just Strengthen the Argument questions, or just questions that ask us to find the most reasonable inference one can make based on the stimulus.

Drilling like-problems is an extremely effective way to learn about and master the different types of Logical Reasoning questions, and I strongly recommend you include plenty  of drill work in your prep work planning.  (For help grouping questions by type, please check out the free LSAT Trainer Question Breakdown.)

At the beginning and middle of your LSAT prep, full sections and full exams can help you gain experience, assess strengthens and weaknesses, and track progress.

As you get closer and closer to test day, full practice exams should become a more and more prominent part of your study routine, and you want to make sure to take at least a few in the weeks leading up to test day. And while it's certainly fine to try a section or two untimed in order to get your bearings or do some assessment, for the most part, it is very important to take every practice section and exam  timed, and in all other ways as realistically as possible. (Please check out the free LSAT Trainer Study Schedules for more help organizing your learning, drilling, and practice tests.)

An Introduction to Logical Reasoning Question Types

Depending on how one chooses to organize them, there are about sixteen different types of Logical Reasoning problems that appear over and over again. The vast majority of questions will require us to evaluate arguments, and the majority of questions that require us to evaluate arguments will ask us to be critical of the reasoning within them.

 

Arguments-Based Questions That Require Critical Evaluation

Identify the Flaw (6-10 per exam)

Weaken the Argument (3-6)

Required Assumption (2-8)

Strengthen the Argument (2-5)

Basic Assumption (0-1)

Match the Flaw (2)

Conform to/Supporting Principle (3-5)

Sufficient Assumption (1-4)

 

Arguments-Based Questions That Do Not Require Critical Evaluation

Method of Reasoning (0-2)

Match the Reasoning (0-2)

Identify the Role (0-4)

Identify the Conclusion (1-3)

 

Outliers

Inference (5-9)

Explain This (2-5)

Give an Example (0-3)

Identify the Disagreement (0-2)

 

For more information about each of these Logical Reasoning question types, please check out this more detailed post: Logical Reasoning Question Types, the Trainer Question Breakdown, and the infographic below.

LSAT Logical Reasoning Question Types Infographic
LSAT Questions Organized By Type

The Trainer Question Breakdown organizes all Logical Reasoning questions from exams 29 - 75 by type. Please click to open.

Please click to open full screen or download.

What are Logical Reasoning Questions Designed to Test?

All of the challenges presented in the Logical Reasoning section can be  organized into three main buckets:

Logical Reasoning Questions Test Reading Ability

For one, they test your exact and correct understanding of certain words critical to reasoning relationships and reasoning concerns, words such as "or," "causes," "must," and "unless." Even more importantly, Logical Reasoning questions test your ability to read for reasoning structure—that is, your ability to see how different parts of the stimulus are meant to relate to one another and how the answer choices relate to the relationships in the stimulus.

Logical Reasoning Questions Test Reasoning Ability

Most commonly, we are asked to use our reasoning ability to evaluate why the support given for an argument does not guarantee the conclusion reached. A minority of questions require us to evaluate how reasoning can indeed come together to support or justify a principle or conclusion.

Logical Reasoning Questions Test Mental Discipline

Finally, Logical Reasoning questions are designed to gauge our ability to stay focused on the task at hand—what I discuss in the Trainer in terms of mental discipline. The test-writers will do this by hiding the critical information in a stimulus within a forest of dense secondary text, and they will do this by asking us questions that are similar to one another, yet not quite the same (such as questions that ask us to strengthen an argument and questions that ask us to find an answer required for the argument to be true), and rewarding those can stay focused on the essential issues and the correct task.

Tips For Logical Reasoning Study Success

Finally, now that we've discussed the challenges that Logical Reasoning questions present, here are some tips to help ensure your study success.

1. Get to know the question types.

The different types of Logical Reasoning problems are all related to one another, yet they also each present a unique challenge. Especially if you are looking to get a top score, it is essential to correctly understand the specific task that each question stem presents, and to develop strategies and habits that align with those specific tasks.

2. Practice correctly identifying arguments.

As discussed above, the vast majority of Logical Reasoning stimuli contain arguments, and, when they do, your job is to correctly identify the argument and to focus in on it. Make sure you work to grow your understanding of argument structure, and that you develop habits for focusing on arguments when you read stimuli.

3. Practice being critical of reasoning.

Again, as discussed above, the majority of Logical Reasoning questions ask us to critically evaluate the reasoning contained within arguments. These problems do not ask us to consider whether the arguments are valid or not. Instead, they begin with the understanding that the given arguments are not valid, and then they ask us to correctly understand why the given support doesn't guarantee the given conclusion, and to react to this in some way—by trying to strengthen the reasoning or fix the reasoning, and so on.

Thus, your default mindset, when asked a question that requires critical evaluation of argument reasoning,  should be to 1) know that the arguments are flawed and 2) focus on trying to understand as carefully as you can exactly how they are flawed.

4. Always try to combine effective learning with effective practice.

The LSAT requires you to be very good at utilizing what you know in the moment, so, whenever you learn something that you find to be useful, try to get plenty of practice at applying what you've just learned.

5. Account for and work to develop your understanding, strategies, and experience.

Work to grow in three areas: understanding of individual question types, as well as the fundamental issues that underlie the design of all problems, strategies for specific situations and the test as a whole, and, as we just discussed, plenty of experience at applying our understanding and strategies on real LSAT problems.

6. Make sure to utilize the most effective study tools.

There is an enormous range in the quality of LSAT learning products available to students today, and quality often fails to correlate to price or reputation. Do careful research of what other students think on popular third-party sites such as top-law-schools, Reddit/lsat, Goodreads, and Amazon, and check out sample chapters and so on when you can. Of course, as the author of The LSAT Trainer (here's a link to eight sample chapters of the book), I believe that it is the very best LSAT study guide available, but perhaps another guide will fit you better, perhaps you want to combine learning products, or perhaps you prefer to learn in a classroom or from a recorded course.

Whatever you choose, again, make sure to choose carefully, and make sure to give yourself the benefit of the most effective LSAT study tools you can find.

7. Drill, drill, and drill some more.

As briefly discussed above, drilling like-problems can have enormous benefits for deepening your understanding and solidifying effective strategies. Whatever study resources you choose, make sure to give yourself plenty of time to practice applying what you learn. Drilling is a great way to develop and strengthen the mental muscle memory necessary for high level Logical Reasoning success.

8. Always review your understanding, strategies, and performance.

Finally, you want to make sure to thoroughly review your work, and to do so from multiple perspectives. First, you want to make sure that you understand exactly why the right answer is right and the wrong ones wrong. Next, you want to carefully evaluate your strategies to make sure that they are effective for helping you eliminate those incorrect answers and arrive at the right one. Finally, you want to assess your own real-time performance. Where you effective at applying your understanding and strategies in real-time? If not, why not? Where did you struggle, and where did you waste time? Careful review can be grueling, but it can also pay off in significant improvement.

About the Author

Mike Kim is the author of The LSAT Trainer, the most popular and acclaimed new LSAT learning product to be released in over a decade. Previously, he co-created ManhattanLSAT. Inspired by self-study students who prepare for the exam on their own, Mike set out to write the ultimate self-study guide, and The LSAT Trainer is the result.

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