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How To Crush LSAT Logical Reasoning (Without Ever Drawing A Single Diagram) — Full Prep Guide + Step By Step Examples

Open up any book on LSAT Logical Reasoning and you’ll likely find elaborate diagrams accompanied by definitions, complicated rules, and logic symbols. 

This technique (diagramming) is typically used by LSAT prep books and companies to teach the fundamentals of logical reasoning. It’s also (more often than not) extended to become a test-taking technique as well.

But there are a couple of problems inherent in this approach.

Probably the biggest one is that it creates the misconception that there’s no other way to learn Logical Reasoning. This, as you’ll see, cannot be further from the truth. In fact, not only do we think diagramming is completely unnecessary to learn and master LR skills, it could also be indicative of a poor overall test-taking strategy. 

Diagramming Is Totally Unnecessary For Logical Reasoning

Here’s why you can (and should) get ahead in Logical Reasoning without ever having to draw a single diagram:

  • It complicates rather than simplifies learning the skills necessary to master Logical Reasoning:

Learning diagramming is confusing. There’s no one way to do it, so you have to spend time figuring out a way that makes sense to you. Plus, having to learn logic symbols and relationships and memorizing what they stand for unnecessarily delays doing the one thing that gives you the biggest ROI: solving actual LR problems.

  • No matter how fast you think you can do it, not diagramming will always be faster.

Logical Reasoning, as you probably already know, are extremely time-sensitive sections. You only have, on average, about 90 seconds to attempt each question and diagramming your way through it is simply not an efficient strategy.

  • There’s a better (and faster) way to a high Logical Reasoning score.

There’s an easier, more unified approach to solving any LR problem: treat everything like an argument that has a consistent structure. What this does is eliminate a lot of the ‘fluff’ that traditionally goes into LR prep: the endless definitions, the boring lessons detailing with every little variation of every single question type, the neverending drills. Once you start treating everything like an argument, nothing in LR will intimidate you anymore because you’ll realize that underneath every problem is the same basic structure that calls for one single process to attack it. 

Let’s break down how exactly this method works. We’ll also show you step by step examples of it in action so you can see how easily it can be used to solve different Logical Reasoning question types.

How To Ace LSAT Logical Reasoning Without Ever Drawing A Single Diagram

At the core of every LSAT logical reasoning question is an argument. 

The structure of this argument can be summarized like this: you have the conclusion, the reasoning that supports the conclusion, and any gaps that exist between the conclusion and reasoning.

This simple overall framework can be used to solve practically every type of LR question.

Here’s how it works, step by step:

  1. Identify the conclusion.

The conclusion is an idea or opinion that usually comes after words like ‘therefore’, ‘thus’, and ‘as a result’. It’s the end-point of an argument in the sense that everything else contained within it is holding it up, like a set of pillars holding up a beam. 

Take a look at this argument:

“Some Greeks are logicians and some logicians are tiresome; therefore, some Greeks are tiresome.” (source)

The conclusion here is “some Greeks are tiresome”.

  1. Understand the reasoning. 

The reasoning is the train of thought the argument maker followed to reach his or her conclusion. It could be a bunch of ideas, observations, facts, pseudo-facts, or anything else that form the ‘pillars’ of the argument. They can be put in the form of: “because…” or “since…”. 

In our example, the argument maker concludes that “some Greeks are tiresome” because 1) “some Greeks are logicians”, and 2) “some logicians are tiresome”.  That’s the reasoning. 

  1. Identify any gaps between the reasoning and conclusion. 

Now we consider if anything’s missing in between the reasoning and the conclusion. In other words, has the argumentator jumped into conclusions? 

Note that for the LSAT we always accept the reasoning at face value. Our job isn’t to attack the evidence or ideas presented in the reasoning, but rather to figure out if there’s a problem with the reasoning leading to the conclusion. 

In our example, the argument maker assumes there’s an overlap between the two populations (Greek logicians and tiresome logicians) although there’s not enough information for us to say that’s the case. When you say “some logicians are tiresome”, there’s the possibility that none of them are in fact Greek.

To illustrate this fallacy another way: 

Some cats are pets and some pets are snakes; therefore, some cats are snakes. 

We can show that the reasoning in both these examples remains the same by assigning variables to the different entities within the argument. Both arguments boil down to this basic structure:

Some of A are B. Some of B are C. Therefore, some of A are C. 

(For the Greek logicians example that would be: A = Greek, B = logicians, C = tiresome.)

(For the cat example that would be: A = cat, B = pet, C = snake.)

Makes sense so far? 

This is literally all you need to ace Logical Reasoning. 

Is that really ALL there is to LSAT Logical Reasoning?!

Yup.

No definitions, no tedious lists to memorize, no complex logic rules, no diagrams.

Just one overall process.

If you can get really skilled at looking at the stimulus and finding the conclusion, understanding the reasoning, and working out how well they connect together, you’ve cracked it. This is really the only foundation you need to ace practically any LR question. 

Now onto the examples!

Solving LSAT Logical Reasoning Problems Without Diagramming: Step By Step Examples 

To really show you how different Logical Reasoning question types can all be approached using this simple conclusion/reasoning/gap process, here are three step by step worked examples. 

LSAT Logical Reasoning Worked Example 1: Strengthen/Weaken Question Type

The key to strengthen/weaken questions lies in finding the missing link between the conclusion and reasoning. The correct answer choice will be the one that addresses the missing link.

We’ll use this question to illustrate the basic process in action:

First, find the conclusion. Remember, a conclusion is an idea or opinion we can put ‘therefore’ in front of.

Conclusion: “Cocoa’s price will continue to rise at least into the near future.”

Next, find the reasoning. This will be any statement we can put ‘because’ or ‘since’ in front of.

Reasoning: 1) “Unusually severe weather in cocoa-producing regions has limited production” 2) “In the first quarter, grinding of cocoa beans rose 8.1 percent in Europe and 16 percent in North America”

Now, find any missing links between the conclusion and reasoning. If we take the reasoning at face value, is there still a possibility that the analysts are jumping to conclusions? 

Missing links: The analysts are assuming that the current situation (the limited supply and increase in demand) will persist for at least some time into the future. In other words, they’re assuming either the shortage of cocoa will persist or the surge in demand will continue, or both. 

So we’ll need to look for something in the answer that contributes to the argument that the current situation will last (in terms of short supply or increased demand).

Now let’s go through the answer choices.

A. Ground cocoa beans can be stored for long periods before they spoil.

How long ground cocoa beans can be stored before getting made into chocolate is irrelevant here. 

B. Several European and North American manufacturers that use cocoa have recently improved their processing capacity.

This statement doesn’t really say anything about the supply or demand of cocoa beans. Processing capacity will not resolve supply shortages — there’s no point in having better processing if the cocoa beans themselves are in short supply. 

C. It takes new cocoa trees five or six years before they start bearing fruit.

This addresses the missing link. If new cocoa trees take a really long time to produce beans, that’s going to slow down supply even further. 

So if true, this would strengthen the author’s argument. 

D. Governments in Europe and North America are likely to change current restrictions on cocoa imports.

We don’t know how the current restrictions are going to change — will they become more severe or will they loosen the restrictions? There’s not enough information in this statement to say it affects the analysts’ argument. 

E. Historically, cocoa production has varied widely from year to year.

Again, there’s not enough information here. Will cocoa production increase dramatically next year? Reduce? Stay the same? We can’t be sure. As it stands, this answer choice doesn’t weaken or strengthen the argument in question. 

The correct answer has to be C. 

LSAT Logical Reasoning Worked Example 2: Assumption Question Type

If assumption questions have previously stumped you, know that they become much more straightforward if you look at it through the lens of conclusion/reasoning/missing link. The key to the hidden assumption lies in the missing link. 

First, find the conclusion. 

Conclusion: “Teachers who value the self-confidence of students should never shy away from teaching complex topics.”

Next, find the reasoning. 

Reasoning: 1) “Students who believe that they are unable to learn complex topics often develop self-confidence problems.” 2) “Students learn from what appear to be teachers’ assumptions about their [the students’] own capabilities.”

Now, identify any gaps between the conclusion and reasoning. Is there a possibility that the teacher here is jumping to conclusions? 

Missing link: The teacher makes a jump from what teachers are actually doing to what they seem to assume (about their students’ capabilities). Put another way, do teachers who never teach complex topics actually appear like they don’t believe their students can learn them?

Now let’s go through the answer choices. We’re looking for an answer that addresses this missing link (the jump from what teachers are doing to what their beliefs seemingly appear to be): 

a) students tend to believe what’s believed by those in authority.

This isn’t relevant since the author’s argument isn’t about teachers being authority figures. 

b) teachers are often guided by their desire to increase their students’ self-confidence as well as by the assumption that their students are unable to learn complex topics

This seems to be taking the argument into a whole other direction. 

c) teachers always value the self-confidence of students

No, this seems to be contradicting the actual conclusion. 

d) students who develop self-confidence problems are unable to learn complex topics

No, this isn’t relevant to the author’s argument. 

e) a teacher who shies away from teaching complex topics will seem to assume that their students cannot learn complex topics

This is exactly what the missing link is — teachers who don’t teach complex topics will seem like they assume their students can’t learn them. 

The correct answer has to be E. 

LSAT Logical Reasoning Worked Example 3: Matching Flaws Question Type

Matching flaws, or parallel flaw questions, are among the most frustrating LR question types because of how time-consuming they can be. You’re expected to analyze not only the stimulus, but also treat each answer choice as its own individual argument before comparing them. 

The most straightforward way we can analyze parallel structures is to reduce them into variables (as we showed earlier). This will help us uncover the underlying structure of argument. Then, we’ll proceed with our basic strategy: find the conclusion, find the reasoning, and uncover the missing links. 

First, let’s assign variables to each element making up the argument in the stimulus:

A = A firefighter with a moustache

B = A firefighter with a tattoo

The argument can be written out like this:

Doug is A. Most Bs are also As. Therefore, Doug is probably B.

(Note: With practice, you won’t need to write all this out. You should be able to quickly substitute the different sections of the argument with variables as you read). 

Now, find the missing link. Just because most Bs are As doesn’t mean that As are probably Bs. To understand this fallacy, let’s take a real world example. Most people who speak French also speak English, since English is a globally dominant language. But that doesn’t mean that most English speakers are French speakers too.  

Now let’s look at the answer choices and see which answer most closely resembles the structure above. 

If we can reject any answer choices because of obvious dissimilarities, we’ll do that as well.

a) Companies that go bankrupt often have trouble making their bill payments. Billsoft is a company that’s not bankrupt. If it does go bankrupt, it will probably have trouble making its bill payments. 

We can reject this outright because the conclusion is an ‘if’ statement and doesn’t match the one in the original argument.

b) Billsoft is a company that’s about to go bankrupt. Most companies that go bankrupt have trouble making their bill payments. Therefore, Billsoft will probably have trouble making its bill payments.

Using variables, this argument states that:

Billsoft is A. Most As are Bs. Therefore, Billsoft is probably B. 

(A = company about to go bankrupt, B = company that has trouble with bills)

This doesn’t make the flaw that’s in the original argument. 

c) Companies that remain solvent in tough times always have excellent management. It’s widely agreed that Billsoft has bad management. Therefore, Billsoft will probably go bankrupt.

Using variables, this argument states that:

Companies that are A are always B. Billsoft is not B. Therefore, Billsoft is probably not A. 

(A = company that remains solvent, B = company that has excellent management)

This structure doesn’t parallel the original argument at all.

d) 10 years ago, Billsoft went bankrupt, and it’s had trouble making its bill payments since. Therefore, most companies that go bankrupt will probably have trouble making their bill payments.

We can reject this because the flaw is an overgeneralization and doesn’t match the one present in the original argument.

e) Most companies that go bankrupt have trouble making their bill payments. Billsoft has trouble making its bill payments. Therefore, Billsoft will probably go bankrupt.

Using variables, this argument states that:

Most companies that are A are also B. Billsoft is B. Therefore, Billsoft is probably A.

(A = company that goes bankrupt, B = company that has trouble with their bills)

It’s presented in a different order, but the underlying structure is the exact same. Here’s the original one again for comparison:

Doug is A. Most Bs are also As. Therefore, Doug is probably B.

The correct answer has to be E. 

What To Do Next

Now that you have a handle on the basics, it’s time to go all out on practice questions.

The trick is to know the various ways in which these components (the conclusion, the reasoning, and the gaps) play out, and that starts — from the get-go — with doing untimed practice questions.

If you need examples of practice questions using this method, check out the book The LSAT Logical Reasoning Process by Trevor Klee. It’s got tons of examples of how to solve every single LSAT LR question type using this exact process. 

For each practice question you attempt, take your time to truly understand the argument and how well the components fit together. Did you get it right? Awesome. Did you get it wrong? Perfect — chuck that question into an error log. An error log is nothing more than a list of questions you got wrong. Note down the question, what the correct answer is, and your own explanation of how to get it right. Review your error log religiously, each time recalling the process through which you can reach the correct answer. 

If you need help maintaining an error log, check out the app 21st Night. You can copy paste, screenshot, or even take a photo of your question and chuck it into the app, and it’ll take care of reviewing for you (check out this post for a guide on how to use the app for LSAT prep).

With quality practice and timely reviewing, the skills needed to carry out this process will become internalized, at which you can start speeding things up and introduce timed practice as well. The end result? You’ll be  able to zip through LR questions with a very high level of accuracy and you’ll have a sense of sharpened intuition that eliminates the need for any diagramming.

Looking for a resource that gives you step-by-step examples on how to solve every Logical Reasoning question type so you can perfect the exact strategy outlined in this blog post? Check out the book The LSAT Logical Reasoning Process by LSAT tutor Trevor Klee. 

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