#13 - In early 2003, scientists detected methane in the

[Robert Carroll]

TB,

At to your first post - answer choice (A) is wrong because what happened prior to 2003 is not relevant. Methane could have been present, getting exposed to UV and dissipating as soon as it's created. Or it might not have been present. Either way, it wouldn't matter for this argument.

LSAT2018,

It does seem like answer choice (D) conflicts with information in the argument, making it a very bad answer choice for an Assumption question.

TB,

If the methane dissolved, it would not be detected. So there definitely is a contrast between detection and dissolution.

Your interpretation of the argument appears correct.

The argument does involve a causal relationship between events, so it counts as a causal argument.

Robert Carroll

[cxmss170]

The explanation for D on the first post is confusing.
"So, we have no reason to think that the methane must have been hit by radiation, and reason to think that it could not have been"

Answer choice said "had been" My thought on this answer choice is wrong because the stimulus talks about "recently" but D said:"had been" which means M had fallen apart, not recently. Please correct me if I am wrong. Thank you

[Jeremy Press]

Hi cxmss170,

Since answer choice D is talking about the methane the scientists detected, it's only talking about a limited slice of methane in the Martian atmosphere, and not about "any" methane in the Martian atmosphere (which the conclusion refers to). The reason answer choice D is probably counter to the stimulus (and not required by the stimulus) is that, since we know methane breaks down when exposed to UV radiation, it is highly likely that the methane the scientists detected in the Martian atmosphere had NOT been exposed to UV radiation. If that methane HAD been exposed to UV radiation, it would have fallen apart, and it would be much less likely that the scientists would have detected it at all. Thus, answer choice D runs counter to the first claim in the stimulus and is not being assumed by the argument. Does that clarify? Hopefully so!

Jeremy

[lsatprep1215]

Hi, I am not 100% getting this question. My original anticipation for this question is: "only recent time methane did not hit by Ultraviolet / all methane before "recently" were gone due to ultraviolet" I did not find what I want to look for in the answer choices, I still end up choosing B as my answer by process of elimination, which is no the ideal way to do the LSAT. Can someone explain if my anticipation make sense/ appropriate?

[James Finch]

Hi LP 1215,

This question contains conditional logic, so identifying the conditional relationships is our first step. Starting with the first sentence, a premise, the stimulus breaks down to:

P1: MethaneMars

P2: Methane UV

Conclusion: MethaneMars is recent

What we don't have accounted for is the UV condition; if there's UV radiation, then the methane will break down. So the correct answer choice will have to address UV radiation.

(A)--Completely off base, as there could have been methane prior that broke down, or methane that existed in 2002 and still was there in 2003

(B)--Contender, as it deals with UV radiation (in sunlight)

(C)--Could be true, but would only suggest that methane on Mars is exposed to sunlight, not that it's recent

(D)--If it were exposed, it would have broken down, so how would it have been detected in the first place?

(E)--Totally irrelevant, as we don't care about what happens in Earth's atmosphere

So (B) is the only contender, but we can still prove it's necessary to the conclusion by using the Assumption Negation Technique:

Not all Martian methane is exposed to sunlight Martian methane isn't necessarily recent

Since it wouldn't have been exposed to UV radiation, it wouldn't be breaking down and thus not necessarily recent. Works perfectly, making it correct.

Hope this clears things up!

[lynnb]

I totally misunderstood this question because I didn't have my "science brain" on and didn't understand that "falls apart" was synonymous to disappearing (I kind of assumed methane could still be detected after having 'fallen apart', but now that I read the chemical explanation it makes much more sense). I ended up choosing A because it seemed to sort of support the idea that the methane had been recently released if there had been no methane previously detected (and I also realize that's a very loose connection, but it was the best I could come up with!). I guess if I run across another science-y question that I'm having trouble understanding I'll try to approach it with a more technical lens. Oh well!

[Jeremy Press]

Hi lynn,

I'll agree that you do need to bring the understanding of the term "falls apart" as meaning "not detectable/recognizable as methane anymore" to the question to capture the assumption. Although I would say that's pretty close to the ordinary and non-scientific meaning of the term "falls apart," right? If my nephew's lego house "falls apart," I can't tell anymore that my (7-year-old-genius; yes you can tell him I said that about him!) nephew made a house (and he'll be very upset, as a result!).

Anyway, with answer choice A you've got a really good reason built into the wording of the answer to eliminate it. The argument is only talking about post-2003 detecting of methane in the Mars atmosphere. How could I know what the author thinks about whether anyone was looking for Mars methane prior to 2003? And how could I know what the author thinks about whether they did or didn't find methane if they were looking? There's no way I can know the author's thoughts on either of those questions. So there's no way to attribute to the author the assumption that there was absolutely no methane in the atmosphere prior to 2003. Answer choice A might work to strengthen the argument a little bit (through a modest showing that the finding of methane was relatively recent). But it's not necessary for the author to assume it.

I hope this helps!

Jeremy

[gwlsathelp]

P1: MethaneMars

P2: Methane UV

Conclusion: MethaneMars is recent

Hi James Finch,

Can you elaborate more on how you diagram out the second part? I recognized that the "when" indicated a sufficient condition, but I diagrammed it as:

sunlight Methane

And how would the assumption connect the premises to the conclusion?

Edit: why is this question considered a CE if there is clearly conditional reasoning present?

[Jeremy Press]

Hi gw,

Let's see if I can help, though James is always welcome to weigh in as well! What you've diagrammed for the second sentence is (in its essence) the contrapositive of what James diagrammed.

The second sentence says, "Methane is a fragile compound that falls apart when hit by the ultraviolet radiation in sunlight." In other words, when hit by UV, methane falls apart. So, as you've correctly observed, that could be diagrammed: UV Methane (where "UV" stands for "hit by the ultraviolet radiation in sunlight"). The contrapositive of that is, "when methane is present (i.e. when it hasn't fallen apart), then it has not been hit by UV," which could be diagrammed as James has: Methane UV.

The connection to the conclusion comes in thinking about that contrapositive. Why would our author think that any methane in the atmosphere must have been released relatively recently? Because we know from our contrapositive that if the methane is present, it has not been hit by UV. So our author must be assuming the methane will not stick around forever, because UV will (in a relatively short time) hit it. There's answer choice B!

Some conditional statements blend causal ideas into them, as this one does. So don't get too thrown off by the labeling. Some people (like the author of the explanation here) will emphasize the causal relationships more and arrive at the answer from that angle. Some (like James) will emphasize the conditional relationships more and still arrive at the correct answer too. That's occasionally a possibility the test affords us!

I hope this helps!

[gwlsathelp]

Yes, this absolutely makes sense! Thank you for your response.