LSAT 105 – Section 4 – Question 05

LSAT 105 - Section 4 - Question 05

February 1999

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Question QuickView	Type	Tags	Answer Choices	Curve	Question Difficulty	Psg/Game/S Difficulty	Explanation
PT105 S4 Q05	+LR	Weaken +Weak	A 1% 159 B 88% 166 C 8% 162 D 1% 154 E 3% 160	120 131 150	+Easiest	144.839 +SubsectionEasier

The most reliable way to detect the presence of life on a planet would be by determining whether or not its atmosphere contains methane. This is because methane completely disappears from a planet’s atmosphere through various chemical reactions unless it is constantly replenished by the biological processes of living beings.

Summarize Argument: Phenomenon-Hypothesis

The author draws the hypothesis that looking for methane in a planet’s atmosphere is the most reliable way to tell whether or not that planet has life. This is because methane will disappear from the atmosphere unless it’s constantly replenished by living organisms’ biological processes. In other words, methane will only persist in the atmospheres of planets with methane-producing life. The author is claiming that where there is methane, there is life, and where there is no methane, there is no life.

Notable Assumptions

Based on the knowledge that only planets with life will have methane in their atmospheres, the author assumes that all planets with life will have methane in their atmospheres. This means that the author is assuming that all life produces methane.

There are other ways of detecting the presence of life on a planet.

This does not weaken the argument. Whether or not there are other ways to detect life on a planet doesn’t affect whether or not methane detection is the most reliable way. All the other methods could be unreliable, we don’t know.

Not all living beings have the ability to biologically produce methane.

This weakens the argument. The author uses “reliable” to mean that methane indicates life, and an absence of methane indicates no life. However, if some living beings don’t produce methane, there could be a planet with no methane that still has life.

We are incapable at present of analyzing a planet’s atmosphere for the presence of methane.

This does not weaken the argument. Whether or not detecting methane is practical doesn’t make a difference to whether or not it would be the most reliable means of detecting life.

Some living beings biologically produce only very small amounts of methane.

This does not weaken the argument. The author never specifies how much methane would be required to detect it in the atmosphere; maybe even the tiniest amount is enough. This is like a weaker version of (B), trying to trick you into thinking it does the same thing.

Earth is the only planet whose atmosphere is known to contain methane.

This does not weaken the argument. Just because we haven’t found other planets with methane in their atmospheres, that doesn’t make a difference to whether methane is a reliable indicator of life. It’s not as though we have another verified life-containing planet to test.

LSAT 105 – Section 4 – Question 05

LSAT 105 - Section 4 - Question 05

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LSAT PrepTest 105 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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