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- Sun Jan 20, 2013 12:00 am
#35290
Complete Question Explanation
Flaw in the Reasoning—CE. The correct answer choice is (D)
Remember that on the LSAT, you are generally expected to accept the author’s premises and focus
instead on the relationship between those premises and the conclusion. There are two premises
here: first, geologists discovered what appear to be worm tracks in a piece of sandstone. Second, the
marks predate the earliest known traces of multicellular life by several hundred million years. The
author thus concludes that the marks are more likely to be the result of geological processes than of
worms. This follows from the assumption that the true origin of multicellular life is unlikely to be
significantly earlier than the earliest known traces. This assumption leads the author to suggest an
alternate cause for the marks, which we are asked to weaken.
Answer choice (A): There are at least two issues with this answer. First of all, the argument is not
dependent on estimating the precise age of a piece of sandstone, since the sandstone could be 300
or 400 million years younger and still be too old for the author to accept it as evidence of previously
unknown life. Second, even if the sandstone is misdated, does that make the author’s attribution of
the marks to geological processes less likely or plausible? Geological processes would be a possible
explanation in various timeframes, so changing the age of the sandstone does not weaken the
author’s explanation.
Answer choice (B): If (B) is true, then geological processes are a viable explanation for marks found
in even older pieces of sandstone than the one from the stimulus. If such processes were active
before this piece of sandstone was marked, then they are more likely to have been active when the
sandstone was marked. This does nothing to weaken the author’s argument.
Answer choice (C): This answer is subject to the same assumption as the original premise. For some
unclear reason, the author thinks that life probably did not exist well before the earliest known traces
of life demonstrate. With that assumption, it is irrelevant whether the marks could be confused for
some life form other than a worm, since the author assumes that there were no life forms at all when
the marks were made. (C) does not help weaken the author’s argument.
Answer choice (D): This is the correct answer choice. The author argues that an alternate cause
accounts for the marks. A good way to attack an alternate cause is to show it to be unlikely or
impossible given the other premises. Answer choice (D) suggests that geological processes cannot
explain the marks since they did not occur at the time and place when the marks were formed. This
weakens the argument and is the correct answer.
Answer choice (E): This answer shows why traces of worm activity are difficult to find, but does
not explain why these marks should be considered evidence of worm activity rather than geological
processes. If anything, (E) would make it easier to believe that the marks are not from worms since
“evidence of their earliest existence is scarce”.
Flaw in the Reasoning—CE. The correct answer choice is (D)
Remember that on the LSAT, you are generally expected to accept the author’s premises and focus
instead on the relationship between those premises and the conclusion. There are two premises
here: first, geologists discovered what appear to be worm tracks in a piece of sandstone. Second, the
marks predate the earliest known traces of multicellular life by several hundred million years. The
author thus concludes that the marks are more likely to be the result of geological processes than of
worms. This follows from the assumption that the true origin of multicellular life is unlikely to be
significantly earlier than the earliest known traces. This assumption leads the author to suggest an
alternate cause for the marks, which we are asked to weaken.
Answer choice (A): There are at least two issues with this answer. First of all, the argument is not
dependent on estimating the precise age of a piece of sandstone, since the sandstone could be 300
or 400 million years younger and still be too old for the author to accept it as evidence of previously
unknown life. Second, even if the sandstone is misdated, does that make the author’s attribution of
the marks to geological processes less likely or plausible? Geological processes would be a possible
explanation in various timeframes, so changing the age of the sandstone does not weaken the
author’s explanation.
Answer choice (B): If (B) is true, then geological processes are a viable explanation for marks found
in even older pieces of sandstone than the one from the stimulus. If such processes were active
before this piece of sandstone was marked, then they are more likely to have been active when the
sandstone was marked. This does nothing to weaken the author’s argument.
Answer choice (C): This answer is subject to the same assumption as the original premise. For some
unclear reason, the author thinks that life probably did not exist well before the earliest known traces
of life demonstrate. With that assumption, it is irrelevant whether the marks could be confused for
some life form other than a worm, since the author assumes that there were no life forms at all when
the marks were made. (C) does not help weaken the author’s argument.
Answer choice (D): This is the correct answer choice. The author argues that an alternate cause
accounts for the marks. A good way to attack an alternate cause is to show it to be unlikely or
impossible given the other premises. Answer choice (D) suggests that geological processes cannot
explain the marks since they did not occur at the time and place when the marks were formed. This
weakens the argument and is the correct answer.
Answer choice (E): This answer shows why traces of worm activity are difficult to find, but does
not explain why these marks should be considered evidence of worm activity rather than geological
processes. If anything, (E) would make it easier to believe that the marks are not from worms since
“evidence of their earliest existence is scarce”.
.