Update 2015: Practice makes perfect. You can find a list of principle questions + explanations for those questions here: http://lsathacks.com/guide/logical-reasoning/questions-by-type/

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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!