How to Solve LSAT “Parallel Reasoning” and “Parallel Flaw” Questions

"Parallel Reasoning" and "Parallel Flaw" questions are found in LSAT Logical Reasoning. Understanding the argument's structure and the nature of its flaws will help you to solve these questions effectively.

This guide will walk you through strategies to confidently tackle both types of parallel questions in your exam.

What Are "Parallel Reasoning" and "Parallel Flaw" Questions in the LSAT?

"Parallel Reasoning" and "Parallel Flaw" questions on the LSAT challenge you to match arguments with answer choices based on their logical structure. These questions require you to identify another argument that mirrors the reasoning or flaw present in the given argument.

Parallel Reasoning questions focus on finding valid arguments with similar logical patterns, while Parallel Flaw questions zero in on matching flawed reasoning.

These top-down questions ask you to find another argument that uses the same reasoning or makes the same mistake as the argument in the passage.

Parallel Reasoning Sample Question

Parallel Reasoning might sound like this:

• Which one of the following is most closely parallel in its reasoning to the reasoning in the argument above?
• Which one of the following arguments is most similar in its pattern of reasoning to the argument above?

Parallel Flaw Sample Question

Parallel Flaw question might sound like this:

• Which one of the following exhibits the flawed reasoning most similar to the flawed reasoning above?
• The questionable reasoning above is most similar in its reasoning to which one of the following?

The only difference between these two question types is that the Parallel Reasoning involves matching an argument’s structure, while Parallel Flaw focuses on matching an argument’s flaw. Parallel Reasoning arguments aren’t usually flawed, but Parallel Flaw argument always are.

The two Parallel question types have similar attack strategies. These questions aren’t as hard as some people make them out to be. Here’s everything you need to know to master Parallel Reasoning and Parallel Flaw questions.

Predicting Parallel Reasoning Questions

The correct answer in Parallel Reasoning questions will be analogous in reasoning, but not necessarily in topic, to the passage. Rather than trying to predict the answer word-for-word, focus on predicting which characteristic of the argument will be repeated in the correct answer.

Before you read the answer choices:

1. Understand how the argument works. Identify its main conclusion and its premises (brush up here) as well as its validity. If the question asks you to match the argument’s “flawed” (or) “questionable reasoning,” you already know the premises don’t prove the conclusion. What’s missing?
2. Restate the gist of the argument in your head. The gist will be simple, so no diagramming! Consider the following passage:

‍Martha: Our profits might drop. If they drop, we must buy more advertising or cut costs. We have already cut costs as much as possible. So if profits drop, we must buy more advertising.

To simplify the gist down to the structure of the argument, you might say:

1. Something might happen.
2. If it happens, we must do one of two options.
3. We can’t do option 1.
4. So if that thing happens, we must do option 2.

Using the example above, a parallel argument on an unrelated topic could be: “My phone might die. If it does, I must hitchhike or walk. I’m not going to hitchhike. So if my phone dies, I must walk.” Try coming up with your own parallel argument!

Predicting Parallel Flaw Questions

In Parallel Flaw questions, the test-writers are telling you that this argument is flawed and that the premises don’t prove the conclusion. Ideally, you’ll pinpoint at least one problem by engaging with the passage the first time you read it. Take a moment to find one and articulate it in general terms.

Focus on exactly what the argument says to avoid subconsciously helping it. Don’t make the very assumptions that the test-writers are trying to hide. Your job is to catch those assumptions. If there are multiple flaws in the passage, Parallel Flaw questions typically focus on the most serious one.

Consider Ryan’s argument:

Ryan: Most cats are pets. Most pets go to a veterinarian doctor at least once every year. So at least some cats go to a doctor at least once every year.

In your head, talk through the argument’s flaws:

Even though most cats are pets and most pets go to the vet at least once a year,  “most” just means “more than half.” It’s possible that 49% of all pets never go to the vet. Heck, maybe only dog owners take their pets to the vet!

We don’t know whether or not cats that are pets fall into that 49% of pets who never make it to the vet. We don’t know what percentage of pets never go. But we do know that those two situations are both possible, so the premises don’t prove the conclusion. This argument is flawed.

Restate the flaw in Ryan’s argument: “Just because most of one thing are a second thing, and most of the second thing do X, that doesn’t mean that some of the first thing do X. Maybe all of the first thing fall into the 49% of the second thing that don’t do X.”

The correct answer could incorporate a timeframe like the passage did, but it doesn’t need to.

You may have noticed that the second premise talks about a “veterinarian doctor” and the conclusion talks about a “doctor.” It works because all vets are doctors. It would’ve been a problem if the phrases “vet” and “doctor” had been reversed, because not all doctors are vets.

Once you’ve understood the flaw in general terms, come up with your own specific example using concrete ideas. For instance, the following argument matches Ryan’s flaw:

Most New Yorkers are Democrats, and most Democrats support unions. Therefore, at least some New Yorkers support unions.

How Similar Is “Parallel?”

When the test-writers ask you for “parallel reasoning,” they’re asking you to find an argument that uses the same kind of logic to justify its conclusion, even if the topics are different. Consider these two (mostly) parallel arguments:

1. Every competitor on Saturday will either give up or request help, but not both. Those competitors who give up will get a participation award. But those who request help will get an achievement award. Therefore, every competitor on Saturday will get an award.

2. All the cows on Jon’s farm tomorrow will graze the pasture outside or stay inside all day. The cows that graze the pasture will get unusually sleepy. The other cows will eat something unusual. So all the cows on Jon’s farm tomorrow will do something unusual.

The reasoning is not perfectly parallel, but it’s close enough. The goal is to look for the argument that is most parallel, and this argument has several important similarities:

• The first premise and the conclusion in argument 2 both use the word “all,” which means the same thing as the word “every” in argument 1.
• The subjects of both arguments all do only one of two things. (The first premise of argument 1 says “but not both.” And in argument 2, it’s impossible to both “stay inside all day” and “graze the pasture outside.”)
• In both arguments, two groups experience different-but-related events. in (In argument 1, both groups of competitors get an award. In argument 2, both groups of cows do something unusual.)
• Both arguments split their subjects into two groups that do not co-mingle.
• Argument 2’s conclusion refers back to all the cows, just as argument 1’s conclusion refers back to every competitor.

What to Look For in the Answers

The correct answer choice will be the one that most resembles the argument in the passage, regardless of the topic. Here are common ways the reasoning in two arguments look alike:

• Look for the same number of premises and conclusions, but not necessarily in the same order. Make sure you’re comparing premises to premises and conclusions to conclusions.

• Look for the same number of ideas in each argument part. In argument 1 above, there are 1) two discrete groups, 2) one consequence that happens for each group, and 3) a conclusion about everyone across both groups. Argument 2 incorporates these ideas too.
• The correct answer will almost always use logical terms that mean the same thing as the logical terms used in the original argument. The correct answer might use usually instead of most, for example. It might use assert instead of argue. If a conclusion is much stronger or much weaker than the passage’s conclusion, it’s probably a wrong answer choice.

Should I Skip Parallel Reasoning and Parallel Flaw Questions?

Many students psych themselves out about Parallel Reasoning and Parallel Flaw questions because they involve evaluating six different arguments. In reality, though, these question types are no more or less difficult in and of themselves. You might encounter a Parallel Reasoning question that’s easier than a Role question.

Questions earlier on in the section tend to be easier. If question #9 is a Parallel Reasoning question, chances are it won’t be very challenging. It’s worth a shot even if it isn’t your favorite question type.

If you’re going to skip any question, decide you’ll skip it right away and don’t waste any time on it. If you have time left at the end of the section you can come back to it.

More on Parallel Questions in the LSAT

How many parallel questions are on LSAT?

The LSAT typically features a few Parallel questions in each Logical Reasoning section. The exact number can vary, but you can generally expect to encounter one or two Parallel Reasoning and Parallel Flaw questions per section. They are mixed in with other types of LSAT Logical Reasoning questions, so it’s important to be prepared for them like you would be for other Logical Reasoning question types.

How to get better at parallel reasoning in the LSAT?

To improve at "Parallel Reasoning" and "Parallel Flaw" questions on the LSAT, focus on mastering argument structure and reasoning patterns. Practice identifying the main conclusion and premises of an argument, and most importantly how the argument goes about proving (or not proving) its conclusion then apply this understanding to recognize similar reasoning or flaws in other arguments. Try your hand at LSAT practice tests and consistently review correct and incorrect answers to become more adept at spotting parallel reasoning and flaws in different contexts. This will enable you to quickly eliminate answer choices by identifying those that are obviously wrong.

What is a flawed pattern of reasoning on the LSAT?

A flawed pattern of reasoning on the LSAT is a logical error in an argument's structure or reasoning. This might include making incorrect assumptions, drawing conclusions that aren't supported by the premises, or using faulty logic. For instance, a common flaw is assuming that because most of one group are in a second group, some of the first group must also be in the second group, which overlooks the possibility that the groups could overlap differently.