chapter12

Getting Familiar

Give yourself about seven minutes to answer the following four questions (we're giving you a bit more time for these because they tend to be longer—in general, don't be afraid to take up to two minutes for a Matching question). Later in the chapter, we'll use these questions to illustrate the important concepts related to Matching questions.

PT30, S2, Q14

It is inaccurate to say that a diet high in refined sugar cannot cause adult-onset diabetes, since a diet high in refined sugar can make a person overweight, and being overweight can predispose a person to adult-onset diabetes.

The argument is most parallel, in its logical structure, to which one of the following?

(A) It is inaccurate to say that being in cold air can cause a person to catch a cold, since colds are caused by viruses, and viruses flourish in warm, crowded places.

(B) It is accurate to say that no airline flies from Halifax to Washington. No airline offers a direct flight, although some airlines have flights from Halifax to Boston and others have flights from Boston to Washington.

(C) It is correct to say that overfertilization is the primary cause of lawn disease, since fertilizer causes lawn grass to grow rapidly and rapidly growing grass has little resistance to disease.

(D) It is incorrect to say that inferior motor oil cannot cause a car to get poorer gasoline mileage, since inferior motor oil can cause engine valve deterioration, and engine valve deterioration can lead to poorer gasoline mileage.

(E) It is inaccurate to say that Alexander the Great was a student of Plato; Alexander was a student of Aristotle and Aristotle was a student of Plato.

PT34, S3, Q23

Societies in which value is measured primarily in financial terms invariably fragment into isolated social units. But since money is not the main measure of value in nonindustrial societies, they must tend in contrast to be socially unified.

The flawed reasoning in which one of the following is most similar to that in the argument above?

(A) Animals of different genera cannot interbreed. But that does not prove that jackals and wolves cannot interbreed, for they belong to the same genus.

(B) Ecosystems close to the equator usually have more species than those closer to the poles. Thus, the Sahara Desert must contain more species than Siberia does, since the latter is farther from the equator.

(C) Insects pass through several stages of maturation: egg, larva, pupa, and adult. Since insects are arthropods, all arthropods probably undergo similar maturation processes.

(D) Poets frequently convey their thoughts via nonliteral uses of language such as metaphors and analogies. But journalists are not poets, so surely journalists always use language literally.

(E) Technologically sophisticated machines often cause us more trouble than simpler devices serving the same function. Since computers are more technologically sophisticated than pencils, they must tend to be more troublesome.

PT31, S2, Q23

Town councilor: The only reason for the town to have ordinances restricting where skateboarding can be done would be to protect children from danger. Skateboarding in the town's River Park is undoubtedly dangerous, but we should not pass an ordinance prohibiting it. If children cannot skateboard in the park, they will most certainly skateboard in the streets. And skateboarding in the streets is more dangerous than skateboarding in the park.

The pattern of reasoning in which one of the following is most similar to that in the town councilor's argument?

(A) The reason for requiring environmental reviews is to ensure that projected developments do not harm the natural environment. Currently, environmental concerns are less compelling than economic concerns, but in the long run, the environment must be protected. Therefore, the requirement for environmental reviews should not be waived.

(B) Insecticides are designed to protect crops against insect damage. Aphids damage tomato crops, but using insecticides against aphids kills wasps that prey on insecticide-resistant pests. Since aphids damage tomato crops less than the insecticide-resistant pests do, insecticides should not be used against aphids on tomato crops.

(C) The purpose of compulsory vaccination for schoolchildren was to protect both the children themselves and others in the community against smallpox. Smallpox was indeed a dreadful disease, but it has now been eliminated from the world's population. So children should not be vaccinated against it.

(D) The function of a sealer on wood siding is to retard deterioration caused by weather. However, cedar is a wood that is naturally resistant to weather-related damage and thus does not need additional protection. Sealers, therefore, should not be applied to cedar siding.

(E) Traffic patterns that involve one-way streets are meant to accelerate the flow of traffic in otherwise congested areas. However, it would be detrimental to the South Main Street area to have traffic move faster. So traffic patterns involving one-way streets should not be implemented there.

PT30, S2, Q6

The student body at this university takes courses in a wide range of disciplines. Miriam is a student at this university, so she takes courses in a wide range of disciplines.

Which one of the following arguments exhibits flawed reasoning most similar to that exhibited by the argument above?

(A) The students at this school take mathematics. Miguel is a student at this school, so he takes mathematics.

(B) The editorial board of this law journal has written on many legal issues. Louise is on the editorial board, so she has written on many legal issues.

(D) All older automobiles need frequent oil changes. This car is new, so its oil need not be changed as frequently.

(E) The individual cells of the brain are incapable of thinking. Therefore, the brain as a whole is incapable of thinking.

Recognizing the Two Types of Matching Questions

These are the LSAT Logical Reasoning questions we love to hate. They are long (each answer choice is an entire argument in and of itself), they are complex, and they generally show up right when we realize we're running out of time. All that said, you can learn to handle these questions quickly (or at least more quickly) if you know what you're looking for.

As always, the first step in tackling a particular question is recognizing what your task is. Here's an outline of the two Matching question types with some simple examples to illustrate:

1. Match the Reasoning. Your job is to choose the answer that best matches the logic used in the original argument.

ORIGINAL: All of the songs on The Duster's new album are ballads. The song “Rain” is on the The Duster's new album. Thus, the song “Rain” is a ballad.

CORRECT ANSWER: All of the children on the playground are in the fifth grade. Lisa is a child on the playground. Therefore, Lisa is in the fifth grade.

Notice that the subject matter of the original (songs on an album) has nothing to do with the subject matter of the correct answer (children on a playground). We don't need to match the subject matter. We want to match the logic. In this case, the common logical structure is:

All X are Y. Z is an X. Therefore, Z is a Y.

2. Match the Flaw. Your job is to choose the answer that contains a flaw similar to the flaw present in the original argument.

ORIGINAL: John is a member of the steering committee, and John is a manager. Since Julie is also a member of the steering committee, she must be a manager.

CORRECT ANSWER: The oak tree in the park is over 15 feet tall. Since the dogwood tree is also in the park, it must be over 15 feet tall.

Again, the subject matter is irrelevant. The important thing is that the correct answer matches the logical flaw of the original. In this case, the flawed argument is:

A is B and A is C. Since D is B, D must also be C.

Match the Reasoning

Let's revisit one of the questions from earlier on:

PT30, S2, Q14

The argument is most parallel, in its logical structure, to which one of the following?

(A) It is inaccurate to say that being in cold air can cause a person to catch a cold, since colds are caused by viruses, and viruses flourish in warm, crowded places.

(C) It is correct to say that overfertilization is the primary cause of lawn disease, since fertilizer causes lawn grass to grow rapidly and rapidly growing grass has little resistance to disease.

(E) It is inaccurate to say that Alexander the Great was a student of Plato; Alexander was a student of Aristotle and Aristotle was a student of Plato.

The key to Match the Reasoning questions is to match up the individual components of the original argument with the individual components of each of the five answer choices. Your job is NOT to look for subject matter connections. Rather, you are looking to match up the corresponding components of the logical structure; that is, you are looking for an answer that reaches the same type of conclusion as the original argument, and uses evidence in the same manner to arrive at that conclusion. The corresponding components of the right answer will be a virtual dead match for those in the original argument.

Let's start by breaking down the original argument:

CONCLUSION: It is inaccurate to say that a diet high in refined sugar cannot cause adult-onset diabetes,

SUPPORTING PREMISE: since a diet high in refined sugar can make a person overweight,

SUPPORTING PREMISE: and being overweight can predispose a person to adult-onset diabetes.

If we were to think of this in argument core form, we'd have:

Since a diet high in refined sugar can make person overweight
+
Being overweight can predispose a person to adult-onset diabetes

It is inaccurate to say that a diet high in refined sugar cannot cause adult-onset diabetes

If we strip away the context, we'd have:

Since X can cause Y
+
Y can predispose to Z

Inaccurate to say that X cannot cause Z

That's it! That's what this whole mess boils down to. Notice that the bolded version strips away the subject matter of the argument. The subject matter is unimportant. That said, we want to be sure that we maintain the logical structure of the argument, since this is ultimately what we are trying to match. The bold version does this. So, to summarize what we've done so far:

Break the argument down into its component parts (e.g., premise + premise conclusion).
Strip the subject matter. If you need to, write the argument on paper in generic form. (Ideally, you would be able to do this your head, but for some difficult arguments it may be helpful to jot things down.)

Now that you've got the logical structure nailed down, go back and try this question again. Attempt to distill each answer choice down to a simple logical form, and see if you can find the one that matches the original. Don't read on until you've given it a fair shot.

Okay, here's our analysis of the choices. The expression inside the box represents our breakdown of the original argument.

TERRIBLE MATCH

None of this is even close! There is no causal relationship between any of these statements.

Answer choice (D) clear and away provides the best match with the original argument.

Notice that the key differentiators turned out NOT to be the subject matter (refined sugar, fertilizer, inferior motor oil, etc.). These are placeholders that are completely irrelevant. Thus, we can strip away this content. What DID turn out to be important were the subtle differences in the words and phrases between the subject matter elements (inaccurate vs. accurate, can cause vs. cause, cannot cause vs. primary cause of, etc.). We'll talk more about these important details later.

Obviously, creating the complete diagrams we created on the previous pages will not be possible under the time constraints of the exam. You should, however, be able to work through this process mentally as you become more accustomed to searching for the subtle differences in phrasing between the argument and the answer choices.

Order Doesn't Matter

In the previous question, we saw that the correct answer was just about a perfect match with the original argument in its physical structure, even down to the order in which the different argument components were presented. However, this is not a requirement for a correct match. The right answer must match the original argument in terms of logical structure (how they make a point), but logical structure isn't impacted by the order in which information is given. Logical structure is important; organizational structure is not. Consider the following simple example:

ARGUMENT #1: All of the songs on The Duster's new album are ballads. The song “Rain” is on the The Duster's new album. Thus, the song “Rain” is a ballad.

ARGUMENT #2: The song “Rain” is a ballad since it is on The Duster's new album and all the songs on The Duster's new album are ballads.

Take a second to ask yourself the following questions: Do these two arguments have the same logical structure? Do they have the same organizational structure?

The organizational structure of Argument #1 is: PREMISE–PREMISE–CONCLUSION. The order of Argument #2 is: CONCLUSION–PREMISE–PREMISE. They have different organizational structures.

The logical structure of both arguments is: All X are Y. Z is X. Thus, Z is Y. These arguments are logically identical.

When asking you to match an answer choice with the original argument, the LSAT will try to confuse you by shuffling the order of the components. Let's take another look at one of the questions from the start of the chapter to see this in action:

PT31, S2, Q23

The pattern of reasoning in which one of the following is most similar to that in the town councilor's argument?

This is a tough, complicated argument. All the more reason to break it down into its component parts and strip the subject matter. We can start by deconstructing the original argument. Notice the bold statements to the right summarize the argument's components by stripping away the subject matter:

BACKGROUND INFO: The only reason for the town to have ordinances restricting where skateboarding can be done would be to protect children from danger.	Describes the general function of an action

OPPOSING POINT: Skateboarding in the town's River Park is undoubtedly dangerous,	Specific reason to implement the action

CONCLUSION: but we should not pass an ordinance prohibiting it.	Claim that the action should not be taken in this case

SUPPORTING PREMISE: If children cannot skateboard in the park, they will most certainly skateboard in the streets.	Result if the action were taken

SUPPORTING PREMISE: And skateboarding in the streets is more dangerous than skateboarding in the park.	How the result would end up being worse than what we started with

Again, we wouldn't necessarily write any of this down, but the representation on the right side of the page is what we want to be thinking about as we read.

Have another look at answer choice (B):

The subject matter in answer choice (B) has nothing to do with the original, but we're not interested in matching subject matter. Let's see if the logical structure of choice (B) gives us a match. Here's choice (B) broken down:

BACKGROUND INFO: Insecticides are designed to protect crops against insect damage.	Describes the general function of an action

OPPOSING POINT: Aphids damage tomato crops,	Specific reason to implement the action

SUPPORTING PREMISE: but using insecticides against aphids kills wasps that prey on insecticide-resistant pests.	Result if the action were taken

SUPPORTING PREMISE: Since aphids damage tomato crops less than the insecticide-resistant pests do,	How the result would end up being worse than what we started with

CONCLUSION: insecticides should not be used against aphids on tomato crops.	Claim that the action should not be taken in this case

We can compare the original argument with answer choice (B):

Answer (B) is the correct answer. Notice that the components of the two arguments match exactly. The only difference is that the conclusion appears in the middle of the original argument whereas the conclusion appears at the end of the argument in answer (B). The components may not be presented in exactly the same order, but remember that order doesn't matter.

Did you eliminate answer (B) because you were thrown off by the difference in order? If so, adjust your approach; concentrate on matching the components, regardless of where they appear physically within the text.

Watch Out for Modifiers

Throughout this book, we have discussed the importance of paying attention to the details. We saw an example of this earlier in the adult-onset diabetes question when we noted the important differences between “can cause” and “cause,” “inaccurate” and “accurate,” etc.

Often on Match the Reasoning questions, the LSAT will alter key details in very subtle ways. These details are often modifiers (words that qualify or describe other parts of the argument).

Here's a new problem. Take 2:00 minutes to select an answer and then we'll discuss.

PT22, S2, Q16

Allowing more steel imports would depress domestic steel prices and harm domestic steel manufacturers. Since the present government will not do anything that would harm the domestic steel industry, it will not lift restrictions on steel imports.

The pattern of reasoning in the argument above is most similar to that in which one of the following?

(A) Building construction increases only when people are confident that the economy is doing well. Therefore, since people are now confident in the economy we can expect building construction to increase.

(B) Since workers are already guaranteed the right to a safe and healthful workplace by law, there is no need for the government to establish further costly health regulations for people who work all day at computer terminals.

(C) In countries that have deregulated their airline industry, many airlines have gone bankrupt. Since many companies in other transportation industries are in weaker economic condition than were those airlines, deregulating other transportation industries will probably result in bankruptcies as well.

(D) The chief executive officer of Silicon, Inc., will probably not accept stock in the company as a bonus next year, since next year's tax laws will require companies to pay a new tax on stock given to executives.

(E) The installation of bright floodlights on campus would render the astronomy department's telescope useless. The astronomy department will not support any proposal that would render its telescope useless; it will therefore not support proposals to install bright floodlights on campus.

For this explanation, we'll present the thoughts that a 170+ test-taker might have while answering the question. Everything in italics will represent the test-taker's real-time thoughts.

I'll read the question stem first so that I know what my task is.

The pattern of reasoning in the argument above is most similar to that in which one of the following?

Matching! This means I need to search for the underlying logical structure in the argument. As much as I can, I'll strip the argument down to its most basic pieces.

This seems like a good argument. Let me get the logical structure down before moving to the answer choices.

Okay, so “allowing more steel imports” is the same as “lifting restrictions on steel imports.” Doing this would “depress steel prices,” which in turn would “harm domestic steel manufacturers.” So it's like this:

And we know that the government wouldn't do anything to hurt domestic steel manufacturers, so we can conclude that it won't allow more imports (it won't lift restrictions).

Allow more imports

hurt domestic steel manufacturers

Government won't do anything to hurt domestic steel manufacturers

Thus, government won't allow more imports.

So, it's kind of like a conditional statement that the government does not want to trigger.

X Y
Don't want Y.
So, won't do X.

Got it. Time for the answers.

(A) Building construction increases only when people are confident that the economy is doing well. Therefore, since people are now confident in the economy, we can expect building construction to increase.

The word “only” is a clue that there may be some conditional logic here. That's a good start.

Building construction increase

people are confident that economy is doing well

And then the conclusion is:

People are now confident in the economy

building construction increase

This is the reverse of the first statement! This logic is flawed. The original was not flawed. I can eliminate this.

Where's the conditional logic? We need a conditional relationship followed by a statement that says the conditional statement won't be triggered. No such statement here. Get rid of it.

Look at the conclusion! “Probably?” I know already that this won't be a match. The original doesn't conclude that the government “probably will not” allow more imports. It says the government “will not” allow imports. This is a very different kind of conclusion. Get rid of it.

The first sentence is the conclusion, and the second sentence is the supporting premise. Again, the conclusion is that the chief executive officer “will probably not….” Get rid of it.

This is the only one left—it better be right! It looks good, but let me break it down.

Installation of bright lights

render telescope useless

Astronomy dept. won't support any proposal that would render telescope useless. Thus, astronomy dept. won't support proposal to install bright lights.

X Y
Don't want Y.
So, won't do X.

This is it! Choose it and move on.

This test-taker was able to move through this question quickly by paying close attention to modifiers. Answer choices (C) and (D) were eliminated immediately because of the word “probably.” Saying that someone or something probably will or will not do something is NOT the same as saying that someone or something will or will not do something.

Be on the lookout for modifiers that change the meaning.

Match the Flaw

Find the Flaw First

Your success on Match the Flaw questions will be driven in large part by your ability to identify the flaw in the original argument before you begin to analyze the answer choices. This requires that you read the original argument critically. Let's revisit another one of our earlier questions to illustrate:

PT30, S2, Q6

The student body at this university takes courses in a wide range of disciplines. Miriam is a student at this university, so she takes courses in a wide range of disciplines.

Which one of the following arguments exhibits flawed reasoning most similar to that exhibited by the argument above?

(A) The students at this school take mathematics. Miguel is a student at this school, so he takes mathematics.

(B) The editorial board of this law journal has written on many legal issues. Louise is on the editorial board, so she has written on many legal issues.

(D) All older automobiles need frequent oil changes. This car is new, so its oil need not be changed as frequently.

(E) The individual cells of the brain are incapable of thinking. Therefore, the brain as a whole is incapable of thinking.

Okay, so let's find the flaw in the original argument first. In this case, the original argument is flawed in that it assigns an attribute belonging to the whole (the student body) to one of the component parts of the whole (Miriam). In other words, just because the entire student body as a whole takes courses in a wide range of disciplines does not necessarily mean that Miriam herself takes courses in a wide range of disciplines. To put it into concrete terms, assume that the student body is comprised of five students, and that each of these students takes courses in a certain discipline:

Roger: Engineering
Taniya: Mathematics
Abinash: Literature
Stan: Spanish
Miriam: Political Science

We can say that the student body as a whole takes courses in a wide range of disciplines, but not that Miriam herself does. She takes courses only in political science. It is therefore flawed reasoning to conclude that the generality necessarily implies something about her specifically.

Now that we have identified the flaw, we can start in on the answer choices. The correct answer will likely have different subject matter, but we know it will contain the same flawed reasoning.

(A) The students at this school take mathematics. Miguel is a student at this school, so he takes mathematics.

This is tricky. At first glance it may seem that this argument contains the same flaw: it assigns an attribute belonging to a larger group (the students) to one of the component parts of that group (Miguel). Be careful. In this context, “The students at this school” means each individual student. If each individual student at the school takes mathematics, and Miguel is a student at the school, he must take mathematics. This argument is rock solid.

Notice that the LSAT attempts to make this answer more appealing by making the subject matter similar to that of the original argument—both relate to courses at school. Remember that the subject matter is irrelevant.

(B) The editorial board of this law journal has written on many legal issues. Louise is on the editorial board, so she has written on many legal issues.

This is the correct answer. An attribute belonging to the whole (the editorial board) is assigned to a component part of that whole (Louise). Just because the board as a whole has written on many legal issues doesn't mean that Louise herself has written on many legal issues. This flaw is an identical match with the original.

This argument works in the reverse direction. Instead of assigning an attribute of the whole to a component part, it assigns an attribute of a part to the entire whole. This type of reasoning is usually flawed. Take the following argument as an example:

“The aqueduct was constructed using only rectangular granite blocks. Thus, the aqueduct must have a rectangular shape.”

This particular argument would obviously be flawed. Of course, the aqueduct as a whole need not have a rectangular shape just because the blocks do. We can't automatically assign a component part's attribute to the entire whole.

Now, after all that, think about the bulldozer again. In the case of answer choice (C), the logic works! If each component part of a bulldozer is heavy, and the entire bulldozer consists of these component parts, then the entire bulldozer must be heavy as well! This argument contains no flaw. Tricky.

(D) All older automobiles need frequent oil changes. This car is new, so its oil need not be changed as frequently.

This argument has nothing to do with the relationship between the whole and its component parts. It does, however, contain a conditional logic flaw. Quick quiz—take a second and see if you can identify the flaw before reading on.

(D) tells us that if a car is old, it needs frequent oil changes:

older auto

frequent oil changes

Then (D) concludes that a new car (the opposite, or negative, of “older auto”) does not need frequent oil changes:

–older auto

–frequent oil changes

You CANNOT simply negate the two components of a conditional statement. While this is a classic flaw, it does not match the flaw present in the original argument.

(E) The individual cells of the brain are incapable of thinking. Therefore, the brain as a whole is incapable of thinking.

Like answer (C), this argument functions in the reverse direction. Instead of taking an attribute belonging to the whole and giving it to a component part, it takes an attribute belonging to a component part and gives it to the whole. But while answer choice (C) was a valid argument, this one is not. Of course the brain is capable of thinking even if the individual components of the brain are not capable of thinking. This argument is flawed, but not in the same “direction” as the original.

This question wasn't too bad, but notice how much there was to learn from the incorrect choices. For Match the Flaw questions in particular, it's crucial that you spend the time during your studies to review the wrong answers. Ask yourself a series of questions:

Does this answer choice even contain a flaw?
If so, and if it's not the same type of flaw as the original, what kind of flaw is it?
How would this answer choice need to be reworded in order to be a correct answer?

For example, let's take answer choice (E):

(E) The individual cells of the brain are incapable of thinking. Therefore, the brain as a whole is incapable of thinking.

How could we rewrite this to make it “correct”? Well, remember that we're trying to match the original flaw, which assigned a characteristic of the whole to one of the members of the whole. We could change (E) as follows:

(E) The brain as a whole is capable of thinking. Therefore, the individual cells of the brain are also capable of thinking.

This would be a much better match with the original.

Forcing yourself through this sort of process is a great way to test the depth of your understanding. In the end, your success on the LSAT won't be determined by how many practice questions you do, but rather by how well you understand the ones you've done.

Let's try another one that's a bit more difficult. Take a few seconds to review the following question from earlier:

PT34, S3, Q23

The flawed reasoning in which one of the following is most similar to that in the argument above?

(A) Animals of different genera cannot interbreed. But that does not prove that jackals and wolves cannot interbreed, for they belong to the same genus.

(C) Insects pass through several stages of maturation: egg, larva, pupa, and adult. Since insects are arthropods, all arthropods probably undergo similar maturation processes.

(D) Poets frequently convey their thoughts via nonliteral uses of language such as metaphors and analogies. But journalists are not poets, so surely journalists always use language literally.

Did you notice the conditional logic cues? If not, go back and look again—they are subtle. Let's start by breaking down the original argument so that we can identify the flaw.

Societies in which value is measured primarily in financial terms invariably fragment into isolated social units.

The word “invariably” (meaning always) is a conditional trigger! Remember, conditional statements express guarantees. “Invariably” is nothing short of a guarantee. We can express this conditional statement as follows:

societies that measure value in financial terms

fragment into isolated units

But since money is not the main measure of value in nonindustrial societies, they must tend in contrast to be socially unified.

Now, since the argument started with a conditional statement, there's a good chance that the second statement can be tied to the first in some way. We want to consider the wording carefully to see if we can find a common term. What do we know about nonindustrial societies? For these societies, value is not measured primarily in financial terms. The argument uses this piece of information to conclude that these societies tend to be socially unified (the opposite of fragmented).

–measure value in financial terms

–fragmented into isolated units

In short, the argument illegally negates the logic given in the first sentence. Flaw! This is the equivalent of saying: “IF something is an apple, THEN it is a fruit. Therefore, IF something is NOT an apple, then it must NOT be a fruit.” What about oranges, strawberries, or bananas? At this point in your studies, this flaw should be obvious to you. If it's not, you need to take some time to review the chapter on conditional logic.

Okay, so we're looking for an answer choice with negated logic. If you think you've got it now, try this question again before reading on.

(A) Animals of different genera cannot interbreed. But that does not prove that jackals and wolves cannot interbreed, for they belong to the same genus.

Wow—complicated argument. The double negatives make it difficult to follow. This is actually a valid argument. Knowing that animals of different genera cannot interbreed tells us nothing about whether animals of the same genus can interbreed. If it helps, you can think about this in terms of conditional logic. The first statement is:

different genera –interbreed

The conclusion states that this does NOT prove that animals of the same genus (the negation of different genera) cannot interbreed. In other words, the conditional statement above does NOT imply:

–different genera –interbreed

The argument is correct in saying that the second statement CANNOT be inferred from the first. Since there is no flaw, this can't be the answer. Eliminate (A).

This argument is flawed in that it uses a generalization to make a conclusion about a specific case. Ecosystems closer to the equator “usually” have more species, but that doesn't mean they “always” have more species. Thus, we cannot automatically conclude that the Sahara Desert has more species than Siberia does. The Sahara Desert could be an outlier case that does not conform to the generalization. If the word “usually” were replaced with “always,” this argument would be fine.

While this argument is flawed, the flaw is not similar to the conditional flaw present in the original argument. Eliminate answer (B).

(C) Insects pass through several stages of maturation: egg, larva, pupa, and adult. Since insects are arthropods, all arthropods probably undergo similar maturation processes.

This argument contains another classic flaw similar to a flaw we saw earlier in the chapter. It takes an attribute of a component part (insects) and assigns it to the entire group (arthropods). This is the equivalent of saying: “Humans can walk on two legs. Since humans are living beings, all living beings probably can walk on two legs.” No!

While this argument is flawed, the flaw is not similar to the conditional flaw present in the original argument. Eliminate answer (C).

(D) Poets frequently convey their thoughts via nonliteral uses of language such as metaphors and analogies. But journalists are not poets, so surely journalists always use language literally.

This first statement can be written in conditional form:

poet

frequent nonliteral use of language

The conclusion attempts to negate both components of the original statement. “Not poet” is the negative of “poet,” and note that “always use language literally” can be considered an opposite, or negative of, “frequent nonliteral use of language.”

–poet

–frequent nonliteral use of language

Thus, this argument is flawed in exactly the same way as the original argument. This is the correct answer.

This answer choice is very similar to answer choice (B) in that it uses a generalization to reach a conclusion about a specific case. Technologically sophisticated machines “often cause us more trouble” than simpler machines, but not always. Thus, we cannot automatically conclude that computers cause us more trouble than pencils.

While this argument is flawed, the flaw is not similar to the conditional logic flaw present in the original argument. Eliminate answer (E).

Conclusion

Match the Reasoning

1. Strip away the subject matter and match the components. As you read the original argument, see if you can make things simpler for yourself by thinking of the logical structure in generic terms. The correct answer will rarely, if ever, contain a subject matter match, but it will always contain a structural match, component for component.

2. Order doesn't matter. Don't let the LSAT fool you! LSAT test writers will attempt to throw you off track by shuffling the order of the argument components. Remember that two arguments can be logically and structurally identical even when the order of presentation differs.

3. Watch out for modifiers. Keep a close eye on the words and phrases that come between the content elements. Must vs. can, most vs. all, sometimes vs. always, probably vs. will, etc. You can often spot incorrect answers by quickly recognizing subtle differences in these modifiers.

Match the Flaw

4. Find the flaw first. Once you know you're dealing with a Match the Flaw question, make it your job to identify the flaw type in the original argument as you read.

5. Learn from the wrong answers. One way to make quick progress on Match the Flaw questions is to make incorrect answer evaluation part of your practice. Analyze each answer choice and try to name the flaw, if one exists. Try to rewrite the answer choice to make it correct. If you can do this consistently, you'll be more likely to see the traps on the real exam.

Time to practice.

DRILL IT: Matching Questions

Give yourself no more than 25 minutes to solve the following problems.

1. PT25, S2, Q2

No one wants this job as much as Joshua does, but he is not applying for it. It follows that there will not be any applicants, no matter how high the salary that is being offered.

The flawed reasoning in the argument above most closely parallels that in which one of the following?

(A) Beth knows better than anyone else how to spot errors in a computer program, yet even she has not found any in this program so far. So it is clear that the errors must all be in the rest of the program.

(B) If anyone can decipher this inscription, it is Professor Alvarez, but she is so involved with her new research that it will be impossible to interest her in this sort of task. Therefore, all we can do now is hope to find someone else.

(C) Although he has the strongest motive of anyone for buying Anna's plot of land, Manfred is not pursuing the matter. Therefore, regardless of how low a price Anna is prepared to accept, she will be looking for a buyer in vain.

(D) The person initially most interested in obtaining the contract was Mr. Moore, but he of all people suddenly withdrew his bid. This means that, no matter how discouraged the other bidders had been, they will now redouble their efforts.

(E) Three times Paul would have liked to take advantage of a special vacation package for himself and his family, but each time he was indispensable at the factory just then. So the more seniority Paul acquires, the greater are the constraints on his personal life.

2. PT24, S2, Q5

Altogether, the students in Ms. Tarnowski's Milton Elementary School class collected more aluminum cans than did the students in any of the school's other classes. Therefore, the Milton student who collected the most aluminum cans was in Ms. Tarnowski's class.

Which one of the following arguments contains flawed reasoning that is most parallel to that in the argument above?

(A) Altogether, more trees were planted by the students in Mr. Kelly's class than were planted by those in Mr. Liang's class and Ms. Jackson's class combined. Therefore, Mr. Kelly's students planted more trees than Ms. Jackson's students planted.

(B) More than half of Milton Elementary School's students play in the band and more than half of the school's students sing in the choir. Therefore, every student at Milton Elementary School either plays in the band or sings in the choir.

(C) Mr. Rowe's Milton Elementary School class raised more money by selling candy bars than Ms. Hunt's class raised by holding a raffle. Therefore, the number of candy bars sold by Mr. Rowe's class was greater than the number of raffle tickets sold by Ms. Hunt's class.

(D) The total number of tickets to the school fair sold by the students in Ms. Ramirez's Milton Elementary School class was greater than the number sold by Milton students from any other class. Therefore, the Milton student who sold the most tickets to the school fair was a student in Ms. Ramirez's class.

(E) Ms. Ventura's Milton Elementary School class assembled more birdhouses than did any of the school's other classes. Since Ms. Ventura's class had fewer students than any other Milton class, her students assembled more birdhouses, on average, than did the students in any other Milton class.

3. PT25, S4, Q20

In some ill-considered popularizations of interesting current research, it is argued that higher apes have the capacity for language but have never put it to use—a remarkable biological miracle, given the enormous selectional advantage of even minimal linguistic skills. It is rather like claiming that some animal has wings adequate for flight but has never thought to fly.

Which one of the following is most similar in its reasoning to the argument above?

(A) Arguing that there are some humans who never sleep is rather like discovering a species of lion that does not eat meat.

(B) Arguing that Earth has been visited by aliens from outer space is rather like claiming that early explorers had visited North America but never founded cities.

(C) Arguing that the human brain has telekinetic powers that no humans have ever exercised is rather like arguing that some insect has legs but never uses them to walk.

(D) Claiming that some people raised tobacco but did not smoke it is rather like claiming that a society that knew how to brew alcohol never drank it.

(E) Arguing that not all people with cars will drive them is rather like claiming that humans invented gasoline long before they used it as fuel for transportation.

4. PT22, S4, Q6

A worker for a power company trims the branches of trees that overhang power lines as a prevention against damage to the lines anticipated because of the impending stormy season. The worker reasons that there will be no need for her to trim the overhanging branches of a certain tree because the owners of the tree have indicated that they might cut it down anyway.

Which one of the following decisions is based on flawed reasoning that is most similar to the worker's flawed reasoning?

(A) A well inspector has a limited amount of time to inspect the wells of a town. The inspector reasons that the wells should be inspected in the order of most used to least used, because there might not be enough time to inspect them all.

(B) All sewage and incoming water pipes in a house must be replaced. The plumber reasons that the cheaper polyvinyl chloride pipes should be used for sewage rather than copper pipes, since the money saved might be used to replace worn fixtures.

(C) A mechanic must replace the worn brakes on a company's vans that are used each weekday. The mechanic reasons that since one of the vans is tentatively scheduled to be junked, he will not have to replace its brakes.

(D) A candidate decides to campaign in the areas of the city where the most new votes are concentrated. The candidate reasons that campaigning in other areas is unnecessary because in those areas the candidate's message is actually liable to alienate voters.

(E) None of the children in a certain kindergarten class will take responsibility for the crayon drawing on the classroom wall. The teacher reasons that it is best to keep all the kindergarten children in during recess in order to be certain to punish the one who did the drawing on the wall.

5. PT23, S2, Q23

An independent audit found no indication of tax avoidance on the part of the firm in the firm's accounts; therefore, no such problem exists.

The questionable reasoning in the argument above is most closely paralleled by that in which one of the following?

(A) The plan for the introduction of the new project has been unmodified so far; therefore, it will not be modified in the future.

(B) The overall budget for the projects has been exceeded by a large amount; therefore, at least one of the projects has exceeded its budget by a large amount.

(C) A compilation of the best student essays of the year includes no essays on current events; therefore, students have become apathetic toward current events.

(D) A survey of schools in the district found no school without a need for building repair; therefore, the education provided to students in the district is substandard.

(E) An examination of the index of the book found no listing for the most prominent critic of the theory the book advocates; therefore, the book fails to refer to that critic.

6. PT20, S4, Q15

Rhonda will see the movie tomorrow afternoon only if Paul goes to the concert in the afternoon. Paul will not go to the concert unless Ted agrees to go to the concert. However, Ted refuses to go to the concert. So Rhonda will not see the movie tomorrow afternoon.

The pattern of reasoning displayed above is most closely paralleled in which one of the following?

(A) If Janice comes to visit, Mary will not pay the bills tomorrow. Janice will not come to visit unless she locates a babysitter. However, Janice has located a babysitter, so she will visit Mary.

(B) Gary will do his laundry tomorrow only if Peter has to go to work. Unless Cathy is ill, Peter will not have to go to work. Since Cathy is not ill, Gary will not do his laundry tomorrow.

(C) Kelly will barbecue fish tonight if it does not rain and the market has fresh trout. Although the forecast does not call for rain, the market does not have fresh trout. So Kelly will not barbecue fish tonight.

(D) Lisa will attend the family reunion next week only if one of her brothers, Jared or Karl, also attends. Karl will not attend the reunion, but Jared will. So Lisa will attend the reunion.

(E) George will not go to the museum tomorrow unless Mark agrees to go. Mark will go to the museum only if he can postpone most of his appointments. Mark has postponed some of his appointments, so he will go to the museum.

7. PT24, S2, Q13

Carl's Coffee Emporium stocks only two decaffeinated coffees: French Roast and Mocha Java. Yusef only serves decaffeinated coffee, and the coffee he served after dinner last night was far too smooth and mellow to have been French Roast. So, if Yusef still gets all his coffee from Carl's, what he served last night was Mocha Java.

The argument above is most similar in its logical structure to which one of the following?

(A) Samuel wants to take three friends to the beach. His mother owns both a sedan and a convertible. The convertible holds four people so, although the sedan has a more powerful engine, if Samuel borrows a vehicle from his mother, he will borrow the convertible.

(B) If Anna wants to walk from her house to the office where she works, she must either go through the park or take the overpass across the railroad tracks. The park paths are muddy, and Anna does not like using the overpass, so she never walks to work.

(C) Rose can either take a two-week vacation in July or wait until October and take a three-week vacation. The trail she had planned to hike requires three weeks to complete but is closed by October, so if Rose takes a vacation, it will not be the one she had planned.

(D) Werdix, Inc., has offered Arno a choice between a job in sales and a job in research. Arno would like to work at Werdix but he would never take a job in sales when another job is available, so if he accepts one of these jobs, it will be the one in research.

(E) If Teresa does not fire her assistant, her staff will rebel and her department's efficiency will decline. Losing her assistant would also reduce its efficiency, so, if no alternative solution can be found, Teresa's department will become less efficient.

Challenge Questions

8. PT21, S2, Q21

If a mechanical aerator is installed in a fish pool, the water in the pool can be properly aerated. So, since John's fish pool does not have a mechanical aerator, it must be that his pool is not properly aerated. Without properly aerated water, fish cannot thrive. Therefore, any fish in John's fish pool will not thrive.

Which one of the following arguments contains an error of reasoning that is also contained in the argument above?

(A) If alum is added to pickle brine, brine can replace the water in the pickles. Therefore, since Paula does not add alum to her pickle brine, the water in the pickles cannot be replaced by brine. Unless their water is replaced with brine, pickles will not stay crisp. Thus, Paula's pickles will not stay crisp.

(B) If pectin is added to jam, the jam will gel. Without a setting agent such as pectin, jam will not gel. So in order to make his jam gel, Harry should add a setting agent such as pectin to the jam.

(C) If stored potatoes are not exposed to ethylene, the potatoes will not sprout. Beets do not release ethylene. Therefore, if Sara stores her potatoes together with beets, the potatoes will not sprout.

(D) If a carrot patch is covered with mulch in the fall, the carrots can be left in the ground until spring. Without a mulch cover, carrots stored in the ground can suffer frost damage. Thus, since Kevin covers his carrot patch with mulch in the fall, the carrots can safely be left in the ground.

(E) If tomatoes are not stored in a dark place, their seeds sometimes sprout. Sprouted seeds can make tomatoes inedible. Therefore, since Maria does not store her tomatoes in a dark place, some of Maria's tomatoes could be inedible.

9. PT21, S3, Q22

Anatomical bilateral symmetry is a common trait. It follows, therefore, that it confers survival advantages on organisms. After all, if bilateral symmetry did not confer such advantages, it would not be common.

The pattern of reasoning in which one of the following arguments is most similar to that in the argument above?

(A) Since it is Sawyer who is negotiating for the city government, it must be true that the city takes the matter seriously. After all, if Sawyer had not been available, the city would have insisted that the negotiations be deferred.

(B) Clearly, no candidate is better qualified for the job than Trumbull. In fact, even to suggest that there might be a more highly qualified candidate seems absurd to those who have seen Trumbull at work.

(C) If Powell lacked superior negotiating skills, she would not have been appointed arbitrator in this case. As everyone knows, she is the appointed arbitrator, so her negotiating skills are, detractors notwithstanding, bound to be superior.

(D) Since Varga was away on vacation at the time, it must have been Rivers who conducted the secret negotiations. Any other scenario makes little sense, for Rivers never does the negotiating unless Varga is unavailable.

(E) If Wong is appointed arbitrator, a decision will be reached promptly. Since it would be absurd to appoint anyone other than Wong as arbitrator, a prompt decision can reasonably be expected.

10. PT22, S2, Q23

Several carefully conducted studies showed that 75 percent of strict vegetarians reached age 50 without developing serious heart disease. We can conclude from this that avoiding meat increases one's chances of avoiding serious heart disease. Therefore, people who want to reduce the risk of serious heart disease should not eat meat.

The flawed pattern of reasoning exhibited by which one of the following is most similar to that exhibited by the argument above?

(A) The majority of people who regularly drive over the speed limit will become involved in traffic accidents. To avoid harm to people who do not drive over the speed limit, we should hire more police officers to enforce the speed laws.

(B) Studies have shown that cigarette smokers have a greater chance of incurring heart disease than people who do not smoke. Since cigarette smoking increases one's chances of incurring heart disease, people who want to try to avoid heart disease should give up cigarette smoking.

(C) The majority of people who regularly drink coffee experience dental problems in the latter part of their lives. Since there is this correlation between drinking coffee and incurring dental problems, the government should make coffee less accessible to the general public.

(D) Studies show that people who do not exercise regularly have a shorter life expectancy than those who exercise regularly. To help increase their patients’ life expectancy, doctors should recommend regular exercise to their patients.

(E) Most people who exercise regularly are able to handle stress. This shows that exercising regularly decreases one's chances of being overwhelmed by stress. So people who want to be able to handle stress should regularly engage in exercise.

11. PT23, S3, Q18

If the recording now playing on the jazz program is really “Louis Armstrong recorded in concert in 1989,” as the announcer said, then Louis Armstrong was playing some of the best jazz of his career years after his death. Since the trumpeter was definitely Louis Armstrong, somehow the announcer must have gotten the date of the recording wrong.

The pattern of reasoning in the argument above is most similar to that in which one of the following arguments?

(A) The museum is reported as having acquired a painting “by Malvina Hoffman, an artist who died in 1966.” But Hoffman was a sculptor, not a painter, so the report must be wrong about the acquisition being a painting.

(B) This painting titled La Toilette is Berthe Morisot's La Toilette only if a painting can be in two museums at the same time. Since nothing can be in two places at once, this painting must some how have been mistitled.

(C) Only if a twentieth-century Mexican artist painted in Japan during the seventeenth century can this work both be “by Frida Kahlo” as labeled and the seventeenth-century Japanese landscape it appears to be. Since it is what it appears to be, the label is wrong.

(D) Unless Käthe Kollwitz was both a sculptor and a printmaker, the volunteer museum guide is wrong in his attribution of this sculpture. Since what Kollwitz is known for is her prints, the guide must be wrong.

(E) If this painting is a portrait done in acrylic, it cannot be by Elisabeth Vigée-Lebrun, since acrylic paint was developed only after her death. Thus, since it is definitely a portrait, the paint must not be acrylic.

12. PT23, S3, Q23

Candidate: The government spends $500 million more each year promoting highway safety than it spends combating cigarette smoking. But each year many more people die from smoking-related diseases than die in highway accidents. So the government would save lives by shifting funds from highway safety programs to antismoking programs.

The flawed reasoning in which one of the following arguments most closely parallels the flawed reasoning in the candidate's argument?

(A) The government enforces the speed limit on freeways much more closely than on tollways. But many more people die each year in auto accidents on freeways than die in auto accidents on tollway. So the government would save lives by shifting funds from enforcement of speed limits on freeways to enforcement of speed limits on tollways.

(B) A certain professional musician spends several times as many hours practicing guitar as she spends practicing saxophone. But she is hired much more often to play saxophone than to play guitar, so she would increase her number of playing engagements by spending less time practicing guitar and more time practicing saxophone.

(C) Automobiles burn more gas per minute on highways than on residential streets. But they get fewer miles per gallon on residential streets. Therefore, gas would be saved by driving less on residential streets and more on highways.

(D) The local swim team spends many more hours practicing the backstroke than it spends practicing the breaststroke. But the team's lap times for the breaststroke are much better than its times for the backstroke, so the team would win more swim meets if it spent less time practicing the backstroke and more time practicing the breaststroke.

(E) Banks have a higher profit margin on loans that have a high interest rate than on loans that have a low interest rate. But borrowers are willing to borrow larger sums at low rates than at high rates. Therefore, banks would be more profitable if they gave more loans at low rates and fewer loans at high rates.

13. PT24, S3, Q16

K, a research scientist, was accused of having falsified laboratory data. Although the original data in question have disappeared, data from K's more recent experiments have been examined and clearly none of them were falsified. Therefore, the accusation should be dismissed.

Which one of the following contains questionable reasoning that is most similar to that in the argument above?

(A) L, an accountant, was charged with having embezzled funds from a client. The charge should be ignored, however, because although the records that might reveal this embezzlement have been destroyed, records of L's current clients show clearly that there has never been any embezzlement from them.

(B) M, a factory supervisor, was accused of failing to enforce safety standards. This accusation should be discussed, because although the identity of the accuser was not revealed, a survey of factory personnel revealed that some violations of the standards have occurred.

(C) N, a social scientist, was charged with plagiarism. The charge is without foundation because although strong similarities between N's book and the work of another scholar have been discovered, the other scholar's work was written after N's work was published.

(D) O, an auto mechanic, has been accused of selling stolen auto parts. The accusation seems to be justified since although no evidence links O directly to these sales, the pattern of distribution of the auto parts points to O as the source.

(E) P, a politician, has been accused of failing to protect the public interest. From at least some points of view, however, the accusation will undoubtedly be considered false, because there is clearly disagreement about where the public interest lies.

14. PT24, S3, Q21

The amount of electricity consumed in Millville on any day in August is directly proportional to peak humidity on that day. Since the average peak humidity this August was three points higher than the average peak humidity last August, it follows that more energy was consumed in Millville this August than last August.

Which one of the following arguments has a pattern of reasoning most similar to the one in the argument above?

(A) The amount of art supplies used in any of the Aesthetic Institute's 25 classes is directly proportional to the number of students in that class. Since in these classes the institute enrolled 20 percent more students overall last year than in the previous year, more art supplies were used in the institute's classes last year than in the previous year.

(B) The number of courses in painting offered by the Aesthetic Institute in any term is directly proportional to the number of students enrolled in the institute in that term. But the institute offers the same number of courses in sculpture each term. Hence, the institute usually offers more courses in painting than in sculpture.

(C) The number of new students enrolled at the Aesthetic Institute in any given year is directly proportional to the amount of advertising the institute has done in the previous year. Hence, if the institute seeks to increase its student body it must increase the amount it spends on advertising.

(D) The fees paid by a student at the Aesthetic Institute are directly proportional to the number of classes in which that student enrolls. Since the number of students at the Aesthetic Institute is increasing, it follows that the institute is collecting a greater amount of fees paid by students than it used to.

(E) The number of instructors employed by the Aesthetic Institute in any term is directly proportional to the number of classes offered in that term and also directly proportional to the number of students enrolled at the institute. Thus, the number of classes offered by the institute in any term is directly proportional to the number of students enrolled in that term.

15. PT25, S2, Q22

It is an absurd idea that whatever artistic endeavor the government refuses to support it does not allow, as one can see by rephrasing the statement to read: No one is allowed to create art without a government subsidy.

The pattern of reasoning in which one of the following is most similar to that in the argument above?

(A) The claim that any driver who is not arrested does not break the law is absurd, as one can see by rewording it: Every driver who breaks the law gets arrested.

(B) The claim that any driver who is not arrested does not break the law is absurd, as one can see by rewording it: Every driver who gets arrested has broken the law.

(C) The notion that every scientist who is supported by a government grant will be successful is absurd, as one can see by rewording it: No scientist who is successful is so without a government grant.

(D) The notion that every scientist who is supported by a government grant will be successful is absurd, as one can see by rewording it: No scientist lacking governmental support will be successful.

(E) The notion that every scientist who has been supported by a government grant will be successful is absurd, as one can see by rewording it: No scientist is allowed to do research without a government grant.

SOLUTIONS: Matching Questions

1. PT25, S2, Q2

No one wants this job as much as Joshua does, but he is not applying for it. It follows that there will not be any applicants, no matter how high the salary that is being offered.

The flawed reasoning in the argument above most closely parallels that in which one of the following?

Answer choice (C) is correct.

If you had to debate this argument, you might say, “People who want the job less than Joshua does might still apply! Especially if the salary is quite high.” So, the argument is assuming that those who want the job less would not want the job if Joshua doesn't.

(C) contains a similar assumption. These who want the land less than Manfred will not want it since he does not. (C) is the only answer that contains this assumption.

We could also arrive at the answer by a more formal process of matching the original argument's structure:

1. Person Y wants X more than anyone. BUT, Person Y isn't trying to obtain X now.
2. Thus, nobody will try to obtain X, even if the offer is made tempting.

The incorrect answers are all mismatches, of course:

(A) somewhat matches the first part; Beth is established as the strongest candidate (a potential match with Joshua's unsurpassed desire), but then the match ends. The original has the strongest candidate not participating, while in (A) she is not succeeding. Finally, the second part has no match for the original idea of making an offer tempting.

(B) looks attractive at first. Professor Alvarez is the most qualified but is unable to participate. What follows should be that there's no hope of anyone completing the task, but instead we learn about a hope for completing it. We want a more pessimistic conclusion!

(D) starts out seeming like a match. Mr. Moore is the most interested candidate (note that this is a bit stronger than the original), and he is apparently uninterested in participating. Like (B), however, (D) ends with a description of how the venture will proceed. This is not a match since the argument should conclude that the venture (the sale) is not going to happen.

(E) can be eliminated based on the first sentence. Paul is not established as being the person whose interest is unrivaled. Furthermore, the conclusion—a proportional relationship—is completely different than the original.

2. PT24, S2, Q5

Which one of the following arguments contains flawed reasoning that is most parallel to that in the argument above?

Answer choice (D) is correct.

Since we're reading a flawed argument, you should have read like a debater and thought of a counterexample such as this: “It's possible that the kid who collected the most cans was in another class, but nobody else in his class collected a lot of cans, so his class did not collect the most overall.” Debating this argument reveals its flaw: the general characteristics of a group don't necessarily apply to each member of that group. And in this argument, we're specifically looking for an argument that refers to a group having more than any other, and for that fact being (mis)applied to an individual in that group.

(D) has the same flaw. Even though Ms. Ramirez's class sold the most tickets, the student who sold the most might be in a different class.

Let's knock out the incorrect answers:

(A) is not flawed. If you were tempted by (A), play with possible number combinations and you'll see that (A) is true.

(B) is indeed flawed—perhaps many of the same kids play in the band and sing in the choir. We can't assume, as (B) does, that the two groups do not overlap. However, that's a different flaw than the one we're looking to match. You can quickly eliminate (B) since there is no mention of a group or an individual having more of something than any other.

(C) can be eliminated because it introduces two items, candy and tickets, while the original only discusses one. The argument in (C) is flawed; the difference in how much money each class raised can't be used to draw a conclusion about the relative number of items sold since there are two types of items and perhaps one was more expensive. But as with (B), this is not the flaw we're looking to match.

(E) can be eliminated because it introduces the element of how many members were in the group.

3. PT25, S4, Q20

Which one of the following is most similar in its reasoning to the argument above?

(A) Arguing that there are some humans who never sleep is rather like discovering a species of lion that does not eat meat.

(B) Arguing that Earth has been visited by aliens from outer space is rather like claiming that early explorers had visited North America but never founded cities.

(C) Arguing that the human brain has telekinetic powers that no humans have ever exercised is rather like arguing that some insect has legs but never uses them to walk.

(D) Claiming that some people raised tobacco but did not smoke it is rather like claiming that a society that knew how to brew alcohol never drank it.

(E) Arguing that not all people with cars will drive them is rather like claiming that humans invented gasoline long before they used it as fuel for transportation.

Answer choice (C) is correct.

For this question we're on the hunt for an answer with a similarly constructed analogy used to draw a similar conclusion. The original uses an analogy to cast doubt on the idea that apes have the capacity for language but haven't used it. The analogy is a hypothetical (and apparently ridiculous) example of an animal having wings for flight but never using them. Note the switch from discussing an unused mental capacity to an unused part of the physical body.

(C) is a strong match. The argument is casting doubt on the idea that we have telekinetic powers, a mental ability, but we choose not to use them. In support, a matching analogy is given: a hypothetical example of an animal having legs but not using them to walk.

Let's look at the incorrect answers:

(A) is a mismatch because it is about “some” humans. The original is about apes in general.

(B) is a mismatch in that it is not about having an ability (and not using it). You might have been tempted by (B) if you thought that the argument implies that aliens have the ability to found a city on whichever planet they visit (and did not choose to do so on Earth). This is a large assumption to make. And, surely aliens might choose not to settle on our planet for legitimate reasons!

(D) is not well-matched to the original because it's about using or not using something that can be created by the animal/human, not about a species not using a part of its anatomy or a mental capacity.

(E) is not even close. This is about not using a product. Furthermore, it seems plausible that we invented gasoline before we started using it as fuel for transportation.

4. PT22, S4, Q6

Which one of the following decisions is based on flawed reasoning that is most similar to the worker's flawed reasoning?

Answer choice (C) is correct.

The first hint of the flaw that we have to match in the question is found in the conclusion's strong language: “…there will be no need for her to trim the overhanging branches….” That's a strong conclusion to reach simply because the tree's owners indicated they might cut it down. Will the owners cut it? When? Before the storm?

(C) demonstrates the same flaw. The mechanic concludes he will not have to replace the brakes since the van is tentatively scheduled to be junked. Will it be? When? Won't the worn brakes be a danger until then?

(A) does not include a conclusion about not doing something because of a chance it's unnecessary. In (A), a limited amount of time is the consideration.

(B) is an argument about a choice, not about not doing something.

(D) does not include a conclusion about not doing something because it's perhaps unnecessary. In (D), the reasoning is that the plan would backfire.

(E) is hard to match to the original. Where's the tentative evidence? Where's the not doing something? It's clear this answer is not a correct match.

5. PT23, S2, Q23

An independent audit found no indication of tax avoidance on the part of the firm in the firm's accounts; therefore, no such problem exists.

The questionable reasoning in the argument above is most closely paralleled by that in which one of the following?

(A) The plan for the introduction of the new project has been unmodified so far; therefore, it will not be modified in the future.

(B) The overall budget for the projects has been exceeded by a large amount; therefore, at least one of the projects has exceeded its budget by a large amount.

(C) A compilation of the best student essays of the year includes no essays on current events; therefore, students have become apathetic toward current events.

(D) A survey of schools in the district found no school without a need for building repair; therefore, the education provided to students in the district is substandard.

(E) An examination of the index of the book found no listing for the most prominent critic of the theory the book advocates; therefore, the book fails to refer to that critic.

Answer choice (E) is correct.

The flaw in the original argument probably jumped out at you: just because an independent audit did not find any traces of a problem doesn't mean that there is no such problem! Even though an independent audit is a reasonable way to check for accounting irregularities, the audit's efficacy is not guaranteed since audits are not foolproof. Furthermore, it could be true that there is a problem, but it just doesn't show up in the accounts (maybe the firm's accounts are wrong or incomplete).

(E) contains the same flaw: just because a book's index doesn't list X does not mean that the book definitely does not contain any reference to X. Maybe the indexer made a mistake.

There are several tempting wrong answers:

(A) has a somewhat similar structure in that a strong conclusion is drawn using information that is relevant but not strong enough. However, unlike the argument in the stimulus, the conclusion in (A) hinges on extending a pattern, not on trusting a supposedly reliable authority.

(B) has a similar flaw to the original in that a conclusion is drawn based on potentially misleading evidence. However, this argument does not have an apparent (though not foolproof) authority. Instead, this argument is flawed because it uses the characteristics of the whole to draw a conclusion about a part.

(C) is clearly wrong because the conclusion makes a dramatic shift to discussing apathy while the premise is about the type of essays included in a publication. The original argument has flaws, but it doesn't have a shift like that.

(D) is similar to (C) in that it includes a dramatic term shift, from schools needing repairs to the education provided being substandard. Again, there's no such shift in the original.

6. PT20, S4, Q15

The pattern of reasoning displayed above is most closely paralleled in which one of the following?

(A) If Janice comes to visit, Mary will not pay the bills tomorrow. Janice will not come to visit unless she locates a babysitter. However, Janice has located a babysitter, so she will visit Mary.

(B) Gary will do his laundry tomorrow only if Peter has to go to work. Unless Cathy is ill, Peter will not have to go to work. Since Cathy is not ill, Gary will not do his laundry tomorrow.

(D) Lisa will attend the family reunion next week only if one of her brothers, Jared or Karl, also attends. Karl will not attend the reunion, but Jared will. So Lisa will attend the reunion.

Answer choice (B) is correct.

This is a great example of where using formally notated logic can be very helpful. Let's start by uncovering the logical structure of the stimulus. We'll use shorthand to keep a brisk pace.

Rhonda will see the movie tomorrow afternoon only if Paul goes to the concert in the afternoon.

R. @ movie P. @ concert

Paul will not go to the concert unless Ted agrees to go to the concert.

We can link this to the first statement. To save time, we'll do that immediately instead of writing it separately:

R. @ movie P. @ concert T. to concert

However, Ted refuses to go to the concert:

–T. to concert

So, Rhonda will not see the movie tomorrow afternoon.

–R. @ movie

The conclusion is based on triggering the contrapositive of the three-part chain we formed above:

–T. to concert –P. @ concert –R. @ movie

Let's look for a match!

(A) looks good at first glance, so let's look more closely.

J. visits –M. pay bills
J. visits J. locates babysitter
J. locates babysitter

Therefore, J. visits.

Where's the chain? Where's the triggering of the contrapositive? Eliminate (A).

(B) also looks good. Let's translate it into formal notation:

G. laundry P. work C. ill
–C. ill
–G. laundry

It's a match!

Here's how one could quickly eliminate (C) through (E):

–Rain + Fresh trout K.
barbecues

We can stop right there! The stimulus is not a compound conditional statement.

(D) begins like this:

L. attend J. or K. attends

Stop. Déjà vu! The stimulus is not a compound conditional statement.

(E) looks good at first glance, so let's look under the hood:

G. @ museum M. agrees to go.
M. @ museum M. postpones most appts.
M. postpones some appts.
Therefore, M. @ museum

This is close, but there's no triggering of the contrapositive. Furthermore, if we read with a lawyer's eye, we might notice that there isn't a chain. Mark agreeing to go to the museum is not the same as Mark going to the museum. Note that “some” is not a negation of “most.” On the LSAT, “some” means “one or more,” which could include “most.”

7. PT24, S2, Q13

The argument above is most similar in its logical structure to which one of the following?

Answer choice (D) is correct.

Let's use this problem to practice some informal notation:

The original argument:

C offers only 2 choices: F or M.
Y did not use F.
So, if Y used C's choices,
Y must have used M.

Answer choice (D):

W offered A only 2 choices: S or R.
If possible, A would not choose S.
So, if A uses W's choices,
Must be R.

There are some slight mismatches (“Y did not use F” is not a perfect match to “if possible, A would not choose S”), but (D) is definitely the best of the bunch:

(A) discusses a choice between two options; however, it lacks a statement that definitively establishes why one option is not, or will not be, selected.

(B) is lacking a definitive statement about which choice Anna will not select. Another mismatch is that the conclusion is a rejection of both choices, not the selection of one, as is found in the original argument.

R has two choices: 2-week vacation in July or 3-week vacation in October.

Plans to hike a trail.

Can't hike trail in October.

If Rose vacations, it won't be what she planned.

The original argument set up two possibilities (French Roast or Mocha), eliminated one possibility, then concluded the other must be true. We don't have that same structure here. If (C) had concluded, “Therefore, Rose will vacation in July,” it would have been a much better match, but, as is, this answer brings up complications the original argument did not, and it reaches a conclusion that is quite different from the type of conclusion the original argument reached. Therefore, (C) is not a good match.

(E) is mismatched in several ways. A glaring problem is that there is no explicit discussion of a choice.

Challenge Questions

8. PT21, S2, Q21

Which one of the following arguments contains an error of reasoning that is also contained in the argument above?

(B) If pectin is added to jam, the jam will gel. Without a setting agent such as pectin, jam will not gel. So in order to make his jam gel, Harry should add a setting agent such as pectin to the jam.

Answer choice (A) is correct.

Let's start by finding the flaw in the stimulus. The first sentence starts with “If” and a quick scan of the argument reveals several conditional logic trigger words, so we'll translate this into formal logic as we read. If your ability to grasp a conditional logic flaw is strong enough that you don't have to write down the formal logic, great. But it's good to know how to do this in case the relationships start spinning in your head.

The first sentence is straightforward to translate: m.a. water aerated.

The second sentence: Thus, since –m.a. –water aerated.

The third sentence: –water aerated –fish.

You can immediately attach that to the second sentence: –m.a. –water aerated –fish

The final sentence gives us the conclusion: –fish. This is basically stating the end of the chain that was triggered by –m.a.

That seems fine, so what's the flaw? Notice that the second sentence is framed as a conclusion (an intermediate one) that is based on the first sentence. If we just look at that part of the argument, we see a problem:

m.a. water aerated, thus,
–m.e. in pool –water aerated.

That's negated logic. Bad logic, bad!

(A) matches perfectly. Let's take it sentence by sentence.

alum brine rep. wat.
Thus, –alum –brine rep. wat.
–brine rep. wat. –crisp
Therefore, –crisp

We can link up some of these: –alum –brine rep. wat. –crisp. But, once again, the second sentence is an illegal negation of the first.

Let's look at the four wrong answers to see how we could eliminate them.

(B) is suspicious because the conclusion is a suggestion about how to obtain a certain result (“In order to…Harry should…”), not a statement of what will occur. Furthermore, the stimulus's conclusion is a negative statement (“not thrive” and “not stay crisp”), not a positive suggestion about how to achieve something.

Formally, answer (B) is incorrect because its structure is this:

pec. gel
–setting agent (pec) –gel
Thus, gel setting agent (pec)

We don't really see the same illegal negation in the second statement, and the conclusion is not simply declaring the end of a chain of logic. In fact, there are no premises to link.

(C) can be eliminated for a similar reason as (B). The conclusion in (C) is a relationship, not a statement of what will occur. Formally, (C) can be represented as:

–ethylene exposure –potatoes sprout
Beets –ethylene released
Thus, potatoes w/beets –potatoes sprout

Again, where is the possibility of linked premises? Where is the illegal negation of a statement?

(D) has a closely matching conclusion since it states what is true, not what would be true if something were done. However, it's suspicious that the conclusion is a positive prediction, “can safely,” instead of a conclusion about how something will not occur.

Looking a bit further into answer (D), we'll see that the structure does not match up. Notice that the second statement is an independent premise, not an intermediate conclusion:

mulch carrots safe
–mulch carrots can be damaged mulch
Thus, carrots safe

This argument is actually valid! If mulch safe, mulch safe! No flaw, no match!

(E) has the right sort of conclusion in that it is negative. However, it's not a great match since it discusses what “could” occur, not what will occur. Furthermore, the first two sentences are about what “can” occur and what happens “sometimes.” These do not match the original.

Formally, the argument is structured as follows:

–tom. in dark some sprout
sprout can be inedible
Maria –tom. in dark
Thus, some can be inedible

This argument is valid. Note that the second sentence is a stand-alone premise, not one that is supported (illegally, and through negation) by the first one.

9. PT21, S3, Q22

The pattern of reasoning in which one of the following arguments is most similar to that in the argument above?

(E) If Wong is appointed arbitrator, a decision will be reached promptly. Since it would be absurd to appoint anyone other than Wong as arbitrator, a prompt decision can reasonably be expected.

Answer choice (C) is correct.

There are a lot of conditional logic triggers and the argument is rather confusing, so we'll use a formal approach.

Anatomical bilateral symmetry is a common trait.

Perhaps the “is” is a conditional logic trigger, but let's keep looking.

It follows, therefore, that it confers survival advantages on organisms.

Ah! This gives us: A.B.S. is common A.B.S. confers surv. adv.

After all, if bilateral symmetry did not confer such advantages, it would not be common.

This is clearly the support. It translates to: A.B.S. NOT confers surv. adv. A.B.S. NOT common

This argument is providing the contrapositive of a statement as its support. Strange seeming, but valid!

Powell –S.N.S. –appointed arbitrator
appointed arbitrator Powell S.N.S.

Remember, for matching questions, the order of the argument is not important as long as the underlying pieces fit together logically in the same manner.

Let's look at the wrong answers, and we'll try comparing what we would “want” each answer to say (to make it a match) to what it actually says:

(A) starts off like this: Sawyer negotiating city takes matter seriously. To complete the structure, we'd want –city takes matter seriously –Sawyer negotiating.

Instead, we find a statement about Sawyer's availability.

(B) is clearly wrong because there are not two conditional statements. Furthermore, “seems absurd,” seems absurd!

(D) begins as follows: Varga away Rivera conduct negotiation. To complete this, we'd want –Rivera conduct negotiation –Varga away.

Instead, we find Rivera conduct negotiation Varga unavailable. This is the negation of what we need.

(E) starts off with this statement: Wong appointed prompt decision. To complete the match, we'd want –prompt decision –Wong appointed.

Instead, the second sentence is quite different: unreasonable to NOT appoint Wong prompt decision expected.

10. PT22, S2, Q23

The flawed pattern of reasoning exhibited by which one of the following is most similar to that exhibited by the argument above?

Answer choice (E) is correct.

We're asked to match the flaw of this question, so let's find it! The conclusion is that people who want to reduce their risk of serious heart disease shouldn't eat meat. Why? Because avoiding meat increases one's chances of avoiding that serious heart disease. That seems like a reasonable argument. However, that premise is actually an intermediate conclusion based on the premise that 75 percent of vegetarians reached 50 without developing heart disease. Since the problem uses numbers to draw a conclusion, we can expect the gap to involve the numbers.

In this case, the health of the vegetarians doesn't tell us much without a control group. There are a couple of problems with using this data to draw that conclusion, but the most glaring is that we don't know if the vegetarians are healthier than meat eaters. Perhaps far more meat eaters reached 50 without heart disease. To summarize, we're looking for an argument that uses a statistic about one group to draw an intermediate conclusion that involves a comparison between groups. It then should go on to use the intermediate conclusion to proscribe something.

Answer choice (E) has the same flaw and structure. The conclusion suggests exercise to help people handle stress. And, like the original, this is based on an invalidly-drawn intermediate conclusion; we don't know how well people who don't exercise are able to handle stress.

Let's look at the wrong answers:

(A) is missing an intermediate conclusion. Also, the conclusion introduces a new element, police officers, an addition that doesn't match the original.

(B) The premise compares two groups, and so the intermediate conclusion can be drawn.

(C) starts out promisingly: the premise is about only one group. However, the intermediate conclusion is much weaker than the original. “Correlation” is a far cry from causation. Similar to (A), there is also the suspicious introduction in the last sentence of “the government,” a new element.

(D) is similar to (B) in that it avoids the flaw we're trying to match. Similar to (A) and (C), the conclusion adds a new element at the end, doctors.

11. PT23, S3, Q18

The pattern of reasoning in the argument above is most similar to that in which one of the following arguments?

(E) If this painting is a portrait done in acrylic, it cannot be by Élisabeth Vigée-Lebrun, since acrylic paint was developed only after her death. Thus, since it is definitely a portrait, the paint must not be acrylic.

Answer choice (C) is correct.

In this argument, the author evaluates a claim: “Louis Armstrong recorded in concert in 1989.” He supports one part of the claim (that Louis Armstrong did record the particular work) but provides evidence (when Louis Armstrong was alive) that definitively proves that another part of the claim (“in 1989”) is incorrect.

We need an answer that matches this reasoning structure:

In (C), we have a painting that is supposed to be both from the seventeenth century and painted by Frida Kahlo. We're told that the painting is indeed from the seventeenth century, but we are provided evidence (Frida Kahlo is a twentieth century artist) that definitely proves that she couldn't have painted it.

Though not all parts of (C) match up perfectly with the original argument, when it comes to the key reasoning issues (evidence that proves a claim to be definitively incorrect), (C) matches up far better with the original argument than the remaining choices do.

(A) is tempting. It begins with a similar type of claim, involving someone who created a certain piece of artwork and involving timing. However, unlike the original argument, it fails to provide sufficient evidence to show that a part of the claim is incorrect. The museum simply stated that Malvina Hoffman was an artist who died in 1966. No part of that can be refuted with the evidence provided. Furthermore, the fact that she was a sculptor, and not a painter, does not mean the museum can't have work that she painted. Many museums have paintings and drawings and such created by people who were not considered painters.

(B) does not present a claim to be proven false. The painting simply has the title “La Toilette” and there is no disputing that title. The author goes on to discuss how the painting can't be a particular painting called “La Toilette,” but this, if anything, only eliminates a possibility about what the painting can be—it does not refute any claim about what the painting actually is.

(D) is similar to (A). Even though Käthe Kollwitz is known for her prints, we have no definitive evidence that she doesn't sculpt, and so we can't say that the claim about the sculpture is wrong.

(E) does not involve the refutation of a claim. It presents clues that help shed light on characteristics that can or can't go together in a portrait (for example, a portrait cannot, at the same time, be created by Élisabeth Vigée-Lebrun and have acrylic), but it does not present this information in order to show that a claim is incorrect. The reasoning in answer (E) is also heavily flawed. We don't have nearly enough evidence to say that if something is a portrait, it can't be done in acrylic. Since the reasoning in the original argument was not flawed, this is a clear sign (E) can't be correct.

12. PT23, S3, Q23

The flawed reasoning in which one of the following arguments most closely parallels the flawed reasoning in the candidate's argument?

Answer choice (B) is correct.

Since we're matching a flawed argument, let's identify the flaws. Reading like a debater, one might counter with the following:

1. It's possible that shifting funds away from highway safety will lead to many more car accidents, endangering more lives instead of saving them, regardless of the increased focus on cigarette smoking. Perhaps the reason the number of highway accidents is so low is because of the well-funded highway safety program.

2. Will the increased investment in preventing smoking actually result in lives saved? Will the government-sponsored anti-smoking campaigns be effective?

More formally, increasing an investment in X at Y's expense does not necessarily result in Y becoming more effective.

Looking at the structure, notice the similarity between the original and answer (B):

The original argument:

Gov't invests more into HS than into CS.
But, CS is more of a problem in terms of Death,
So, Gov't would improve situation with Death
if it shifts investment from HS to CS.

Answer choice (B):

Musician invests more into G than into S.
But, S is more crucial than G in terms of $.
So, musician would improve situation with $
if she shifts investment from G to S.

This isn't a perfect match (for example, the original discusses investing in reducing a problem, while the answer discusses investing in what is more important), but it is the closest when compared to the other answer choices.

(A) does not match the original's structure. It begins by discussing the comparative investment in tollway and freeway safety in terms of how closely the speed limit is enforced in each place. However, (A)’s conclusion is about the amount of money spent. To match the original, it should draw a conclusion about shifting enforcement of speed limits. Furthermore, the argument actually reverses the argument's conclusion. If it were to match the original, the fact that more people die on the freeways should support the idea that there be more focus on freeways. Instead, the argument suggests increasing enforcement (or funds for enforcement) for tollways.

(C) can be eliminated because there is no discussion of the current level of comparative investment in two related options.

(D) is extremely tempting:

Swim team invests more in Back than Breast.
But, Breast is better in terms of time.
So, team would win more meets
if it shifts time from Back to Breast.

Notice that line three does not reference “time,” and instead switches to “meets.” The original continues to argue its point in terms of Death. Furthermore, in the original, the situation with the choice that's receiving less investment is supposed to be worse (more smoking deaths), but in answer (D), the situation with the under supported choice is already better.

(E) can be eliminated because it is missing a comparison of how much is invested in each of two choices. Profit margin is not a match with this.

13. PT24, S3, Q16

Which one of the following contains questionable reasoning that is most similar to that in the argument above?

Answer choice (A) is correct.

The flaw here is apparent if you are reading like a debater. The fact that recent evidence does not show any mischief doesn't mean that the accusation of falsification based on now-missing data should be dismissed. K may have falsified the data that has disappeared!

(A) has the same flaw. Just because the current records don't show any embezzlement does not mean that the charge of embezzlement should be ignored. Just like with the original, the missing records might indicate embezzlement.

The wrong answers can all be quickly eliminated because of specific phrases:

(B) is clearly a mismatch since it states the accusation “should be discussed.” The original is about dismissing accusations.

(C) has no loss of evidence. Also, the discussion of work being done after something else does not correspond to anything in the original argument.

(D) should be quickly eliminated upon seeing “justified.” The argument is supposed to conclude by suggesting that the charges be dismissed.

(E) can be eliminated because it discusses “some points of view.” There's no match for that in the original.

14. PT24, S3, Q21

Which one of the following arguments has a pattern of reasoning most similar to the one in the argument above?

Answer choice (A) is correct.

The argument we're to match is pretty straightforward:

P: E is directly proportional to H.
P: H was higher in August this year than in previous year.
C: E was higher this year.

(A) has the same structure:

P: Art supplies is directly proportional to # of students.
P: # of students 20% higher last year than previous year.
C: More art supplies were used last year.

(B) can be eliminated because of the mismatched modifier “usually.” Furthermore, (B) is missing a premise about one time period having more of something; instead it states that the number of courses remained constant.

(C) is easily eliminated because it ends with a suggestion. If an original argument doesn't include a suggestion, the match can't either. (C) is also missing a match with the second premise, similar to (B).

(D) first discusses the number of classes an individual student enrolls in, and then switches to discussing the number of students. This shift is not found in the original.

(E) is a clear mismatch because it includes a second factor that affects the proportional relationship (it's both the number of classes and the number of students). Furthermore, the argument's conclusion is a relationship (“Thus, the number of classes…is proportional…”), instead of a simple statement about number (“…more energy was consumed…”).

15. PT25, S2, Q22

The pattern of reasoning in which one of the following is most similar to that in the argument above?

(A) The claim that any driver who is not arrested does not break the law is absurd, as one can see by rewording it: Every driver who breaks the law gets arrested.

(B) The claim that any driver who is not arrested does not break the law is absurd, as one can see by rewording it: Every driver who gets arrested has broken the law.

(D) The notion that every scientist who is supported by a government grant will be successful is absurd, as one can see by rewording it: No scientist lacking governmental support will be successful.

Answer choice (A) is correct.

Bring out the formal logic notation!

It is an absurd idea that whatever artistic endeavor the government refuses to support it does not allow,

Absurd: –gov. support –gov. allow

as one can see by rephrasing the statement to read: No one is allowed to create art without a government subsidy.

gov. allow gov. support

For either sentence you may have first derived the contrapositive of what is written above. That's fine, as long as the argument's structure became apparent to you:

It's absurd to say –X –Y, and this is clear if you reword that as Y X.

This matches answer choice (A).

It's absurd to say –arrested –break law, and this is clear from break law arrested.

Most of the incorrect answers are quite tempting until you uncover each one's logic:

(B) has an illegal negation: It's absurd to say that –arrested –break law, and this is clear from arrested break law.

(D) has an illegal negation: It's absurd to say that supp. succ., and this is clear from –supp. –succ.

(E) shifts terms. The first statement is about support and success, while the second is about support and being allowed to do research.