Supplemental Logical Reasoning Questions #1

[srcline@noctrl.edu]

Hello,
I am struggling with some questions on the logical reasoning supplemental questions.

Question 1 stem states that "which one of the following, if accepted by Clay Moltz, would require him to reconsider his conclusion? I'm assuming this means its asking to weaken his conclusion. SO his conclusion that I thought was this indicates that the astronomer's model is wrong, and life as we know it exists only on the planet Earth. Is this correct?

Based on this I choose answer choice A. However the correct answer choice was C. Detecting planets outside our solar system requires more sophisticated instruments than are currently available. IS the key word instruments because the argument mentions model?

Thankyou
Sarah

[Laura Carrier]

Hi Sarah,

Yes, you are correct that you are being asked to find an answer choice that will weaken Clay Moltz’s conclusion, though the question stem is definitely worded in an obscure way. And you have correctly identified the conclusion as the last sentence. At that point in answering a weaken question, you would want to think about exactly what the conclusion is asserting and why the author wants us to believe it, looking for a potential gap between the premises and the conclusion.

Remember that Moltz says, as you quoted, that “[t]his indicates that the astronomer's model is wrong, and life as we know it exists only on the planet Earth.” Thus, he wants us to believe that “life as we know it exists only on the planet Earth.” And you are asked to find an answer choice that makes this conclusion less likely to be true.

Answer choice (A), which is about “forms of life other than life as we know it, doesn’t make Moltz’s specific conclusion about life as we know it any less likely to be true, because (A) is offering evidence about a different group (other forms of life), and we have no reason to believe that this has any bearing on the forms of life Moltz is talking about. To like answer choice (A), you would have to make a leap of reasoning and assume that, if other forms of life can exist, that may mean that life as we know it is more likely to be able to exist as well, so Moltz’s conclusion is less likely to be true. But you don’t want to choose an answer choice that requires an assumption like that to be provided by you.

But think about the evidence Moltz offers to convince us of why his conclusion is right: All he tells us in support of his claim is that “astronomers to date have not detected even one planet outside our solar system.” He is asking us to accept not detecting any planets means that they aren’t there and thus couldn’t be supporting life as we know it. But does that evidence allow any possibility that his conclusion could be too extreme, that there could be an exception to it?

Answer choice (C) comes along and says that detecting planets outside our solar system would require more sophisticated instruments than are currently available, suggesting that Moltz’s sole piece of evidence could have an alternate explanation: maybe the planets haven’t been detected because the instruments can’t see them, rather than because they’re not there. If that’s the case, then it does make Moltz’s conclusion less likely, since it increases the likelihood that there could be planets out there supporting life as we know it, but which simply haven’t been detected.

So it is not really a matter of the word “instruments” relating in any specific way to the model that Moltz is rejecting (though you are right to always be alert for the subtle implications of words on the LSAT!), but more a matter of finding a place where the premises don't fully support the conclusion and looking for an answer choice that will exploit that potential gap.

I hope this helps!
Laura

[srcline@noctrl.edu]

Hello Laura

This explanation helps greatly, I was getting tripped up on finding the gap between the premise and the conclusion.

Thankyou Sarah

[swt2003]

The question seems to test the "absence of evidence is not evidence of absence flaw".

The conclusion essentially states that, if X has not been detected (absence of evidence), then this proves X doesn't exist (evidence of absence).

C. weakens the conclusion by showing that maybe planets and life as we know it do exist but, we can't detect them.

[Francis O'Rourke]

That's exactly right Swt2003!