#19 - Court analyst: Courts should not allow the use of DNA

[Administrator]

Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (C)

The court analyst argues that DNA should not be admissible in court because experts disagree as to how reliable DNA evidence is. The concern seems reasonable, and it’s tempting to agree. However, the analyst does not present the details of the nature of the disagreement. Imagine the disagreement were about something more familiar, such as the temperature of a drink. If everyone agrees that a certain drink is scalding hot, it doesn’t matter how scalding hot it is. One should still be cautious when taking a sip. However if some believe that the drink is hot, while others believe it is cold, it would make sense to try to get more information before taking a sip.

In this stimulus, the analyst is unclear as to the details of the uncertainty in the scientific community. If some believe DNA tests are 50% reliable while others think they are 100% reliable, the disagreement would be significant enough to suggest that the DNA tests may not be reliable. However, if it is a case where some scientists believe the testing is 99.998% accurate while others believe the testing is 99.999% accurate, the disagreement in the scientific community is one of degree rather than of substance. That is, in the second example, the scientific community seems to agree that the testing is pretty reliable; they just differ as to exactly how reliable it is. If the experts agree that the testing is in fact reliable to at least some degree, it should not be controversial to admit the evidence.

Answer choice (A): It is always important to be sensitive to the difference between fact and opinion. An argument that describes what should be is never tell us objective facts about the world. The stimulus is about what should or should not be admissible. The fact that courts could admit evidence regardless of reliability does not affect if they should admit.

Answer choice (B): The analyst does not say that the evidence should not be admitted unless it is certain to be accurate; he or she argues that it should not be admitted unless there is agreement as to how accurate it is.

Answer choice (C): This is the correct answer choice. The author fails to consider the nature of the degree of disagreement among scientists. As explained in detail above, the failure to distinguish between significant disagreement and minor disagreement makes the conclusion suspect.

Answer choice (D): The stimulus does not argue that witnesses would be required to agree on the reliability of evidence prior to admission. In fact, according to the stimulus, scientific witnesses agreeing on the reliability of evidence would not necessarily be enough. The scientific community as a whole must agree.

Answer choice (E): Though the argument limits itself to what should be true in criminal cases, this is not a problem with the argument. Limiting the scope of an argument is not always problematic; it is only when the limitation leaves out a key consideration that it becomes a flaw. Here, the problem with the argument was related to the issue of consensus within the scientific community, and not with the specific venue. The argument would have been just as faulty if the author had also considered using the evidence in civil cases.

[akanshalsat]

For this question, I got C correct but how does the stimulus
*fail* to take into account that experts may disagree about exactly how reliable they are if in the second sentence it says "there exists considerable controversey among scientific experts about how reliable these tests are"--> arent they taking that exact sentence into account?

[Vaidehi Joshi]

@akanshalsat, yes, I think you're hitting the nail on the head without realizing it. What you're pointing out is true, but that's also the flaw.
The flaw is that the stimulus assumes from the fact that there is controversy among experts about HOW reliable these tests are that some scientists do NOT think they are reliable. (C) basically points out the flaw by saying something like "but scientists can all be on board that these tests are generally reliable, while disagreeing about the extent to which they are reliable. in other words, scientists don't necessarily think they are UNreliable!"

so what you're pointing out is a flaw, but it isn't properly taken into account in the stimulus, because the stimulus makes an unwarranted leap in logic, from the possibility that experts could be mildly-to-strong on board with the accuracy of these tests, to instead saying that some experts are NOT on board with these tests at all.

Does that help clarify? Essentially, the nuance that you yourself seem capable of seeing here is not seen by the court analyst!

[ronibass]

I chose answer choice A. I understand why C is correct I just am not completely sure why A is incorrect. Is it because answer choice A is using information outside the scope of the LSAT about the court's authority? I chose answer choice A because if courts had the authority to exclude information then that could point to the need for there being "widespread agreement in the scientific community" as a flaw since the courts could just exclude this anyways.

[Claire Horan]

Hi Ronibass,

Administrator does a great job above of explaining why (A) is incorrect:

Answer choice (A): It is always important to be sensitive to the difference between fact and opinion. An argument that describes what should be is never tell us objective facts about the world. The stimulus is about what should or should not be admissible. The fact that courts could admit evidence regardless of reliability does not affect if they should admit.

The stimulus says courts should exclude certain evidence. Answer choice (A) says courts have the authority to exclude any evidence. In general, you cannot say an argument about what "should" happen (a normative argument) is flawed because it leaves out what does or could happen (a descriptive argument).

[ToadKing]

Hi,

I was hoping you could resolve my confusion with answer (C).

My problem is that the 3rd sentence of the stimulus uses the same language as the 2nd sentence, but answer (C) forces you to interpret the phrasing in two different ways:

(2) There exists considerable controversy among scientific experts about how reliable these tests are.
(3) Unless there is widespread agreement in the scientific community about how reliable a certain test is...

In my opinion, answer (C) forces you to interpret sentence (2) as there being a percentage disagreement (99.999% accurate vs 99.998%) but sentence (3) would have to be interpreted as a distinction between classes (not reliable, reliable, highly reliable, etc.) — even though both sentences use almost identical phrasing (the only difference being a change from plural [these tests are] to singular [a certain test is]).

For this reason, I was hesitant with choosing (C) and even went back to this question at the end to spend extra time on it. Admittedly, no other answer choice is attractive. However, answer (C) seems to commit a flaw that has shown up on past flaw questions: shifting the interpretation/usage of a phrase. In other words, you have to commit a flaw to point out a flaw in the stimulus. Is this too far fetched?

Thank you!

[Robert Carroll]

Toad,

Answer choice (C) does not force a changed interpretation for the second and third sentence. The author has pointed out in the premises that there is controversy about how reliable the tests are. It's fair to say there is disagreement about how reliable the tests are. The author then says that one constraint on allowing such tests would be widespread agreement about how reliable the tests are. So there is disagreement, and we need agreement in order for the tests to be used. The author concludes we shouldn't use the tests. The problem is that disagreement is compatible with agreement in this (and many other) situations. The experts disagree about something. Do they disagree about everything? In order for the last premise to entail that we shouldn't use the tests, they must be no agreement at all. Proving there's some disagreement doesn't prove there is total disagreement. So the issue is that the author does not realize that experts may agree and disagree about different things, so evidence of disagreement is not incompatible with the existence of agreement as well.

Robert Carroll

[ltowns1]

Hi, so I actually thought about this question a little differently. Since you really can’t quantify the words “considerable” and “widespread” other than to say that the former means at least some and the latter means at least a majority, I saw a scenario possible where there were some scientists (let’s say 10 percent of all scientists) who could’ve thought the percentage of reliability was 50 percent for the test , whereas 90 percent of all scientists believed it was reliable within the 90-99 percent range? That for me was a little easier to wrap my head around. That’s a little different than what some explanations have said, so I’m wondering if that is a valid way to think about the argument? Thanks

[Chandler H]

Hi ltowns,

Good question! I see where you are coming from, but in this case, I'd say that the test authors are using the word "considerable" not in a strictly quantifiable sense, but instead meaning "worth consideration" or "notable."

If an answer choice brought up the meaning of the word "considerable," it would make perfect sense to consider the exact meaning of that word, but since none of the answer choices do, it's best for you to assume that "considerable controversy" is mutually exclusive with "widespread agreement."

I hope this makes sense!

[ltowns1]

Hi ltowns,

Good question! I see where you are coming from, but in this case, I'd say that the test authors are using the word "considerable" not in a strictly quantifiable sense, but instead meaning "worth consideration" or "notable."

If an answer choice brought up the meaning of the word "considerable," it would make perfect sense to consider the exact meaning of that word, but since none of the answer choices do, it's best for you to assume that "considerable controversy" is mutually exclusive with "widespread agreement."

I hope this makes sense!

Got it! Thanks so much for the help!