LSAT Principle Questions, Part III (Examples and Explanations)

Update 2015: Practice makes perfect. You can find a list of principle questions + explanations for those questions here:


In part I of this series on LSAT principle questions, I explained what a principle is.

In part II, I discussed the three main types of LSAT principle questions.

In this third and final part, I’m going to explain an example of each type of question, and then show you a list of all the principle questions from tests 29-38.

A Refresher: The Three Main Types of Principle Questions

The three main types of LSAT Principle questions are:

  1. Strengthen
  2. Parallel Reasoning
  3. Extraction

I’m going explain an example of each type.

Example of a Principle-Strengthen Question

This explanation is for question 24 from Section III of the June 2007 LSAT. It’s the free LSAT, available here. Go take a look, do the question, then come back and read this.

Conclusion: Romantics are wrong (when they say that people aren’t evil but that institutions can make people evil).

Reasoning: The romantics don’t understand the relationship between institutions and people. Institutions are just groups of people.

Analysis: The sociologist ignores that groups can change the individuals in the group. Your body is just a group of cells, but those cells are changed because of the fact that they’re in your body.

In other words, the sociologist is ignoring the possible “whole-to-part” relationship. The right answer rules out this possibility, and therefore makes his argument stronger.

A. This only tells us how much evil people can do. It doesn’t tell us why they are evil.
B. This tells us that all human institutions are imperfect. But it doesn’t say anything about whether institutions can make people become evil.
C.  We don’t know whether the sociologist or the romanticists could be considered     optimistic. This answer doesn’t let us say anything about either group.
D. This completely ignores why people can be evil.
E. CORRECT. This is tricky, but it eliminates a major flaw in the sociologist’s argument. It’s possible that an institution could make people evil, even if everyone in the institution is good. Going to school changes people, working in a corporation changes people. In real life, taking part in any institution can change us.

This answer choice eliminates that possibility. Groups can’t affect their members. So if some humans in a group are evil, then they must have been evil before they joined the group.

Example of a Principle Parallel Reasoning Question

This explanation is for question 10, from Section IV of Test 29. You can find it in The Next Ten Actual Official LSATs. Try that question, then look at this explanation.

Conclusion: Parents should not necessarily raise their children the way that experts recommend.

Reasoning/Principle: Parents are the ones with direct experience on which methods work.

Analysis: This is a pretty good argument. Parents will learn from experience, whether expert theories are right or wrong.

The right answer will depend on the personal experience of a group. The group may wish to disregard expert advice if the experts don’t have direct experience.

A. This doesn’t depend on the personal experience of musicians.
B. This is tempting, but different. Experts in parenting might be interested in giving good advice; they’re just not very good at it. And this doesn’t involve the personal experience of consumers.
C. CORRECT. The climber has direct experience with the mountain while other experts do not.
D. Here the experts know more than the farmer. That’s different. Also, this doesn’t say what anyone should do.
E. This does tell you what to do. But it isn’t talking about experts and has nothing to do with direct experience.

Example of a Principle Extraction Question

This explanation is for question 19, from Section I of LSAT 29. You can find it in The Next Ten Actual Official LSATs. Try that question, then look at this explanation.

Conclusion: The shipping manager is also to blame for the delay.

Reasoning/Principle: He knew the contractor is usually late and he should have planned for it.

Analysis: This is a good argument. It was foreseeable that the contractor would be late so the shipping manager was negligent for not planning for it.

A. CORRECT. The arbitrator’s argument makes this reasonable assumption. If you don’t consider foreseeable risks then you’ll have a lot of problems.
B. The manager would agree with this principle. The stimulus argues that managers should know that contractors can be late.
C. This does sound like a good idea, but it may not always be possible. The arbritrator never claimed that lateness itself was the problem. The manager failed to plan for the possibility of lateness. The main point of the argument is that the manager is to blame because the problem was foreseeable.
D. Does a manager directly supervise a contractor? Usually not, and the stimulus doesn’t say. This doesn’t help us blame the manager.
E. The arbitrator says that the contractor is also to blame.

List of Principle Questions

I’ve made a list of all the principle questions from LSATs 29-38. If you don’t already have it, you can find these tests in the “Next Ten Actual Official LSATs”, from LSAC.

Principle – Parallel Reasoning

Test 29, Section IV, # 10
Test 32, Section IV, # 3
Test 32, Section IV, # 18
Test 35, Section I,   #  7
Test 36, Section I,   # 17
Test 36, Section III, # 15
Test 38, Section I,   #  7
Test 38, Section IV, #  7
Test 38, Section IV, # 23

Principle – Extraction

Test 29, section I,  # 19
Test 29, section IV, # 17
Test 30, Section II,  # 5
Test 31, Section II,  # 22
Test 32, Section I,   # 3
Test 33, Section I,   # 18
Test 34, Section III, # 1
Test 37, Section II,  # 18

Principle – Strengthen

Test 29, Section IV,   # 7
Test 29, Section I  # 22
Test 30, Section IV, # 23
Test 31, Section II,  # 24
Test 31, Section III, # 4
Test 31, Section III, # 26
Test 32, Section IV,  # 8
Test 33, Section I,   # 21
Test 33, Section III, # 6
Test 34, Section II,  # 20
Test 34, Section III, # 16
Test 35, Section I,   # 2
Test 35, Section IV  # 11
Test 36, Section I,   # 15
Test 36, Section III, # 20
Test 37, Section II,  # 22
Test 37, Section II,  # 24
Test 37, Section IV, # 21
Test 38, Section I,   # 3
Test 38, Section IV, # 4

Want more explantions? I’ve written explanations for every question from LSATs 29-38 and 62-75+. Have a look!

LSAT Principle Questions, Part II (Question Types)

Update 2015: Practice makes perfect. You can find a list of principle questions + explanations for those questions here:


In part one of this post on LSAT Principle questions, I covered what a “principle” is.

Now, in part II, I’m going to tell you about the main types of principle questions that appear on the LSAT.

Check out Part III for explanations to a few sample principle questions, and a list of all the principle questions from LSATs 29-38.

First, A Warning

I don’t think questions types are very important. You don’t need to memorize these types, and learning them won’t help you very much if you’re having trouble with the underlying concepts (conditional statements, applying a rule to a situation, assessing an argument, finding conclusions, etc.)

So don’t get hung up on the technical details. That said, I think going over the questions types can be somewhat useful for two reasons:

  1. The question types test different skills. If one type of question seems much harder to you than the others, then you know you need to focus on the skills needed to answer that type of question.
  2. Different question types have different requirements for choosing the right answer. It’s surprisingly common for students to answer questions wrong because they misunderstood what they were being asked. Studying the question types can help you get used to what you’re being asked to do.

Beyond that, I’ve rarely seen students get any results from studying questions types. So please don’t try to memorize this information.

Types Of LSAT Principle Questions

The three main types of LSAT Principle questions are:

  1. Strengthen
  2. Parallel Reasoning
  3. Extraction

Strengthen Principle Questions

Strengthen questions are the most common type of principle questions. They are the simplest principle questions; they’re just like the regular strengthen questions.

  • The stimulus will be an argument.
  • There will be a flaw in the argument.
  • You can make the argument stronger by addressing the flaw.

The only difference is that the right answers will be principles. You must pick one that, if true, would force someone to believe the argument was stronger.

As with all questions based on arguments, it’s very important to identify exactly what the conclusion of the argument is. It’s surprisingly hard to identify conclusions correctly, and most people are bad at it.

If you find yourself unsure, pick some questions, try to find the conclusions, and then explain to a friend what the conclusion of each argument is, and why. Or post the same on a LSAT forum. This sounds silly, but it’s one of the best ways to get better at finding conclusions. If you’re not getting them 100% of the time, then don’t kid yourself: you don’t fully understand arguments, and you need practice.

Question Stems for Strengthen Principle Questions

  • Which of the following principles most helps to justify the argument?
  • Which principle would provide the most support for the argument?
  • Which principle would most strongly support the argument?

All of these questions stems ask you to help the argument. You don’t need to prove the conclusion correct. You just have to make the argument somewhat stronger.

Parallel Reasoning LSAT Principle Questions

These questions are closest to parallel reasoning questions. In parallel reasoning questions, you must figure out the structure of the argument in the stimulus. Then you find the argument in the answer choices that has the same structure.

You answer parallel reasoning questions using the same process. Find the principle illustrated by the stimulus. Then find the answer choice that illustrates that same principle.

Sometimes, Principle Parallel Reasoning questions give us a situation that illustrates a principle (without stating it explicitly). We have to find out what the principle is, and then find a situation that matches.

Other times, the stimulus will explicitly state a principle, and we must find a situation where that same principle applies.

In either case, it’s the same process: identify principle, apply to new situation.

Powerscore calls these questions “Must be True” principle questions, but I have no idea why. They have nothing in common. In those questions, we make a conclusion from a set of facts (not an argument). In parallel reasoning principle questions, we have to find a situation that matches the stimulus.

Question Stems For Principle Parallel Reasoning

These question stems don’t say the words “Parallel Reasoning”. That’s what makes principle questions so hard to classify. But if you look at some examples, you’ll see that questions with these question stems all ask you to do the same thing: find a parallel situaiton.

  • Which of the following situations most conforms to the principle illustrated above?
  • Which of the following illustrates a principle most similar to that illustrated above?
  • Which one of the following judgements conforms to the principle stated above?

Principle – Extraction Questions

These questions present a situation that illustrates a principle. The answer choices list five principles. You have to figure out which one matches the principle illustrated by the stimulus.

I call these “extraction” questions because you have to extract the principle that’s within the argument.

Essentially, these questions ask you to identify an assumption made in the argument.

They are somewhat similar to necessary assumption questions, with one major difference: the assumptions in principle questions tend to be warranted assumptions, and the arguments tend to be good arguments.

Not all assumptions are errors. We make many warranted assumptions in everyday conversation. If I say “I will meet you at the cafe tomorrow”, I am assuming:

  • The cafe will not burn down.
  • I will survive until tomorrow.
  • You won’t get kidnapped before meeting me.

These are all reasonable assumptions, and therefore, they are warranted assumptions. In general, if everyone would tend to agree that an assumption is reasonable, then it is warranted.

Necessary assumption questions make unwarranted assumptions. Necessary assumption questions present flawed arguments.

These principle questions instead make reasonable assumptions. We have to extract the principle that underlies the stimulus.

These are the closest thing to a “pure” principle question type. The stimulus presents a situation, and then five principles. You have to choose the principle that best fits the situation. This has no parallel with other question types.

Note: Powerscore calls these “Justify” or “must be true” questions. Again, I’m not really sure why. But principle questions are hard to classify, and it’s best not to get hung up on which words to use.

Principle – Extraction Question stems

  • Which of the following principles underlies the argument?
  • The reasoning most closely conforms to which principle?
  • The facts conform to which generalization?

The answer choices will always be principles, and the stimulus will be an argument or set of facts that illustrates a principle.

Watch Out For “Conforms”

Vocabulary: Watch out for the word “conform”! It isn’t always used in the same way. Here are two question stems which use it differently:

  • “Which of the following situations conforms most closely to the principle illustrated in the stimulus”
  • “Which of the following principles conforms most closely to the situation in the stimulus”.

Did you notice the difference? The first type gives us a principle in the stimulus (e.g. children should not play unless they clean their room and eat their dinner). The answer choices will be five situations involving children playing, and we have to decide which one is justified by the stimulus. That’s a parallel reasoning principle question.

The second question stem presents us with a situation, and asks which principle conforms with that situation. This is asking us to extract the principle that can be found within the stimulus.

New Types of Principle Questions

The more recent LSATs have introduced a few different types of principle questions. They’re pretty rare, so there’s no point trying to memorize the new types. But if you want to have a look, I’ve listed a few below:

LSAT 64, section I, question 21: Flawed reasoning principle question

LSAT 63, Section I, question 18: Application Principle Question – Strengthen

LSAT 63, Section III, question 22: Application Principle Question – Sufficient Assumpton

Did that answer all of your questions about principle questions? Is there anything you still want to learn about? Let me know in the comments!

Check out Part III for explanations of sample principle questions, and a list of principle questions from LSATs 29-38.

LSAT Principle Questions, Part I

Update 2015: Practice makes perfect. You can find a list of principle questions + explanations for those questions here:


People often find LSAT principle questions confusing.

At first glance, this is strange. Principle questions are similar to regular question types. There are strengthen questions, parallel reasoning questions, etc. So why are LSAT principle questions hard?

It’s because principle questions are more abstract. The principles aren’t necessarily tied to a specific situation, and that’s hard to think about.

This is a two part blog post. In the second half, you’ll learn about LSAT principle questions types, and you’ll find a list of principle questions.

The first half covers something more basic, but even more important: what a principle is.

What Is A Principle?

In real life, we get away with using words imprecisely. This is fine. But on the LSAT (and in law), you need to be very precise with words. So you should know exactly what a “principle” is.

A good dictionary is surprisingly helpful for many LSAT terms, including this one. A principle is:

  1. A fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning.
  2. A rule or belief governing one’s personal behavior.

If you accept a principle is true, it should change your thoughts or actions. And LSAT principle questions ask you to accept principles as true! So the right principle will change what you think of a situation.

You are not trying to figure out if the principles are true in real life. That is the wrong question to ask.

Instead, ask yourself “If this principle were true, would it change the situation?”

Narrow vs. Broad Principles

It’s important to know exactly when a principle applies to a situation. Consider these two principles. They sound similar, but one is much broader:

  • “New parents should eat a healthy diet.”
  • “Anyone who works should eat a healthy diet.”

The second principle is much broader.

If you accept that a principle is true, it will affect how you act or how you think about a situation.

Suppose you accepted the above principles, and that you work. You’re deciding whether to eat a chocolate bar. The principle does the job for you. Don’t eat it.

“I work, therefore I should eat a healthy diet. Therefore, I should not this chocolate bar.”

Take-away: Principles are often if-then (conditional) statements. You can use them to make formal logical deductions. In certain situations, a principle will force you to change your mind.

Bonus Question: What about someone who doesn’t work, and isn’t a parent. Should they eat a chocolate bar?

We don’t know. The principles don’t tell us anything about people who don’t work and aren’t parents. We have no idea what they should or should not do.

An Example

Let’s look at an example.

A robber comes to your house, and steals your computer. You lose all your pictures and music. Later, the robber turns himself in to police. He apologizes, says the robbery was a moment of weakness, and repents.

The robber is prepared to accept whatever punishment the law thinks appropriate. This is the robber’s third crime, and he will go to jail for life if found guilty.

Unfortunately, the computer was broken in the robbery, and you can’t get any data back.

The police come to you, and ask if you want to press charges. What do you say?

You might have already decided what to do. Or maybe you’re stuck and can’t decide between vengeance and pity. How do you decide, and what could force you to change your mind if you’ve already decided?

Applying Principles To The Example

There are certain principles that, if accepted, would force you to decide one way or the other. Suppose you believed that:

“Anyone who commits a crime must be punished, for the good of society”.

This principle tells you what to do. The robber committed a crime. Therefore, he must be punished. If you accept the principle, you have to believe this is true, even if you think the robber did a good thing by turning himself in.

Likewise, if you believe the following principle, the situation is clear:

“Anyone who repents of a crime deserves mercy and should not be punished.”

You can’t press charges if you truly believe this.

These are the kind of principles to look for. They express a firm belief that can change how you view a situation.

Some Principles Don’t Affect Anything

The wrong answers on an LSAT principle question typically describe a principle that has no effect, or a situation that isn’t affected by a principle. It’s very important to be able to identify when a  principle has no effect.

So let’s look at a few principles that won’t help us decide anything. See if you can figure out why they’re useless:

  • “All convicted criminals must be sent to jail.”
  • “You should not have mercy for a criminal who does not repent.”
  • “You should only punish a criminal if they cause irreparable damage.”
  • “You should only have mercy for a criminal if they repent.”

Did you figure out what was wrong with them? The first two apply to the wrong groups. The robber is not yet a convicted criminal. And since the robber did repent, the second principle doesn’t apply.

This is very important. A principle that doesn’t apply to the case at hand has no effect.

The final two principles are trickier. They tell us necessary conditions for punishing a criminal or having mercy. The first one says you can’t punish a criminal who didn’t cause permanent damage.

But our criminal did cause permanent damage. So this principle is useless. It tells us we could punish him, but not that we should or that we must.

The same analysis applies to the principle about mercy. If you find this confusing, it means you need to do more work on what sufficient and necessary conditions mean. I’ve written more about this in my Basic Logic section.

That’s it for discussion of what a principle is. Check out Part II for more on LSAT principle question types, and a list of principle questions from tests 29-38.

Then, take a look at Part III to find explanations for a few sample principle questions, and to see a list of all the principle questions from LSATs 29-38.

LSAT Principle Questions: Strengthen

LSAT principle questions can seem confusing, but they’re really just other question types in disguise. For example, often we’re asked to use a principle to strengthen or weaken an argument.

These questions are just like normal strengthen or weaken questions, with one twist: the answers are phrased as abstract principles.

What Question To Ask Yourself About Each Answer

The right answer should force you to change your mind about the argument’s conclusion.

Let’s say I make the following argument:

“Even though there are useful ways we could spend tax money, we should cut taxes to boost economic growth.”

You may not agree with that argument, but you can see there’s at least a potential case to be made. If you do agree with it, you can surely see that it is not perfect.

Here’s a wrong answer:

“Economic growth is a good thing.”

It sounds a little tempting. The conclusion said that we should aim for growth, and this says growth is good.

But…would this principle force anyone to change their mind. Some people might think that we could achieve even more good by spending the tax money.

Further, it’s a very obvious principle. Practically everybody agrees that economic growth it good. That makes it a warranted assumption, something that we could assume anyone because no one would disagree with it.

Take Each Statement At It’s Weakest

Most people look at the answers to an LSAT question, and try to see whether it’s possible they’ll be useful. That’s the wrong approach. You should ask yourself whether it’s possible that the answer wouldn’t be useful.

The wrong answer above said that economic growth is good. But how good? We don’t know. Maybe economic growth is the best thing in the world. Or maybe it’s good, but not very good. Maybe it ranks a little higher than “steamed peas” on the scale of goodness.

So, properly speaking, the question to ask yourself is:

“If everyone agreed that economic growth was slightly good, would that convince them that we definitely should cut taxes to boost economic growth?”

“No”, is the answer to that question. There’s still room for disagreement.

What a Right Answer Looks Like

Take this statement:

“If some action will boost economic growth, then the government should take that action.”

Now ask yourself:

“If someone accepted that statement is true, would they have to agree that we should cut taxes to support economic growth?”

Yes, they would. The correct answer on a “principle: strengthen/weaken” question will force you to change your mind, if you accept that the principle is true.

Some students think that this kind of answer is “too strong”. I have no idea what that means. A strong answer choice does more than it needs to, but that’s fine, as long as the answer does help the argument. If you’re supporting an argument, you can never be “too strong”.

Update 2015: I’ve now written thousands of free explanations at LSAT Hacks, including explanations for principle strengthen questions: