#11 - Scientist: To study the comparative effectiveness of

[Administrator]

Complete Question Explanation

Flaw in the Reasoning, SN. The correct answer choice is (A)

The scientist begins this dialogue by describing a study of experimental medications involving two
groups of people with athlete’s foot. One of the groups of athlete’s foot sufferers was given only
medication M, and the other was given only medication N. The only people to be cured had been
given medication M. In other words, if any given study participant was cured, that person was on
medication M. This conditional statement can be diagrammed as follows:

• Cured On medication M

The reporter responds with a statement that indicates that he has made an inaccurate assessment of
the scientist’s statement. The reporter’s invalid conclusion is that anyone who was not cured was not
on medication M. This is actually a Mistaken Negation of the scientist’s statement, which can be
diagrammed as follows:

Mistaken Negation: Cured On medication M

This is not a valid conclusion because all we know from the scientist’s statements is that anyone who
was cured was on medication M. This could mean that just one person was cured from a large group
of participants that had been on medication M. So it is not valid to conclude, as the reporter does,
that everyone on M had been cured.

Thus, we know the flaw in the reasoning of the reporter is conditional in nature, and in seeking the
correct answer choice, we need an answer that describes the conditional error (preferably using
conditional terms such as “necessary” or “sufficient,” although that is not a requirement).

Answer choice (A): This is the correct answer choice. The reporter considers the premise that M
can possibly cure athlete’s foot (perhaps even in just one person), and incorrectly concludes that M
always cures athlete’s foot. This answer is tricky because it actually describes the contrapositive of
the Mistaken Negation above:

Contrapositive of Mistaken Negation: On medication M Cured
(a.k.a. the Mistaken Reversal)

The contrapositive of a Mistaken Negation is the Mistaken Reversal of the original statement
(remember, the Mistaken Negation and the Mistaken Reversal of the same original statement are
contrapositives of each other). Thus, because this answer choice describes a relationship that is
functionally identical to error in the reporter’s statement, it is correct.

Answer choice (B): The reporter’s error is not in drawing invalidly broad conclusions based on a
small sample, but rather in misunderstanding the conditional statement provided by the scientist.

Answer choice (C): The reporter’s statement only concerns people involved in the study, reflecting
no mistaken presumptions about those who were not involved in the study.

Answer choice (D): The reporter’s response deals only with study participants, so there is no reason
to consider the circumstances of those who may be cured without either of the two medications
studied.

Answer choice (E): This potentially confusing incorrect answer choice provides a fairly convoluted
conditional point—that the reporter wrongly presumes that there are not many people who can be
cured only by avoiding medication M. But the reporter’s actual conclusion regards those who took
medication M, and the reporter’s mistake is in presuming that all of those participants were cured.

[reop6780]

Q1 ) Can someone help me with the conditional relation in the last sentence?

"The only people whose athlete's foot was cured had been given medication M."


The way I did in my head was M Cured

Then, I compared it with the reporter's conclusion, "if anyone in the study had athlete's foot that was not cured, that person did not receive medication M."

I created another diagram of M Cured


Finally, I saw the question that asks, "ERROR" that I could not find as both conditional relation was the same in my head.

Q2) Is my conditional relation wrong?

Q3) What is the answer A supposed to mean anyway?

How can we tell the scientist meant that M CAN cure while the reporter interpreted it as M ALWAYS cure???

Thank you

[Nikki Siclunov]

Hi reop6780,

Thanks for your question!

Yes - you have an error in your conditional reasoning diagram. Take a look at the following sentence more closely:

The only people whose athlete's foot was cured had been given medication M.

According to your interpretation of this statement (M Cured), everyone who received the medication was cured. This is not necessarily true: the only people who got cured are those who had been given the medication. In other words, receiving a medication is a necessary, not a sufficient, condition for being cured:

Cured M

Sentence constructions that begin with the phrase "the only" can be tricky. Here's the lowdown:

• Although "only" and "only if" are necessary condition indicators, the element that immediately follows the phrase "the only" is actually the sufficient condition.

Here are a few examples:

The only people who get into law school are those who take the LSAT.

What does that tell us? Taking the LSAT is a necessary condition for getting into law school (LS LSAT)

Another example:

The only way to explore Tibet is to hire a local guide.

Explore Tibet Local guide

Does that make sense? Let me know!

[reop6780]

Oh wow ! You helped me in most direct and efficient way! Thanks, Nikki

[Jkjones3789]

Hello, I went with D for this Flaw question. Could you please explain to me why it's A. I seem to be having a little trouble with Flaw questions. Do you have any suggestions about how to improve my performance on such questions too ? Thank you.

[Adam Tyson]

On this one, take note of the very important conditional language in the stimulus - you'll find it in the last sentence, and it diagrams as:

C (cured) -> M (given medication M)

Seeing that conditionality and knowing that it's a flaw question, you should know to be on the lookout for a mistaken reversal or mistaken negation.

The reporter then says something that you could diagram this way:

C -> M

A clear mistaken negation, right? Answer A describes that for you. If it helps, imagine that of 10 people who took M, only 5 were cured. The scientist would still be right, but the reporter's conclusion would be wrong - there were 5 people not cured who did indeed take M.

So what's wrong with D? That answer suggest that maybe, sometimes, C -> M, and that the reporter didn't think of that. Was that his mistake? No, he didn't overlook that, because his answer was about those that were NOT cured, not those that were. Also, answer D is too broad in it's scope - it could certainly be true that some folks who were not involved in the study get cured without taking M, but within the limited scope of our study that simply didn't happen - our scientist said that anyone in the study who got cured took M, and we accept that premise as true.

When you see conditional language in a flaw question, look for answers that describe conditional flaws and you will be well on the way to picking the credited response.

Good luck!

[bk1111]

Hi, when I read A, I thought that was the Mistaken Reversal. What would the Mistaken Reversal have sounded like?

[Francis O'Rourke]

Hi Bk, the Mistaken Reversal of the stimulus's statement:

The only people who were cured were given medication M
C (cured) M (given medication M)

would be written and diagrammed as

Everyone who had been given medication M were cured
M (given medication M) C (cured)

[ahoward1234]

Question 11, logical reasoning section 2 of the official lsat superprep II --is this a flaw in reasoning questions or a point at issue? The question stem seems like it's a flaw question but the stimulus is set up as a point at issue. I'm lost on this one,.please help me. I don't want to be confused. Taking in June

Thanks!

[Charlie Melman]

Hi ahoward,

This is a flaw in the reasoning question that just happens to have the two-speaker construction that point at issue questions do. When the question stem says "error in reasoning," it identifies itself as a flaw question. You're right about everything you said, but we can still have a flaw question with two speakers.

Hope this helps!