- Thu Jan 24, 2013 12:00 am
#35732
Complete Question Explanation
Flaw in the Reasoning. The correct answer choice is (E)
We tend to approach strangers if the stranger is of our own approximate age, and most long-term
friendships begin by approaching a stranger. On that basis, the author considers it likely that longterm
friends are of the same approximate age.
It may be helpful to diagram the argument contained in the stimulus as if it contained conditional
reasoning. However, keep in mind that the relationships in each premise are less than absolute, due to
the use of such phrases as “likely,” “probably,” and “most.” Nevertheless, since our primary objective
is to understand the logical structure of the argument as clearly as possible, such a conditional
approach would be justified, albeit with a caveat.
The first premise of the argument can be diagrammed as follows:
StrangerSimilar Age = One is of a similar age as a stranger
CAStranger = Comfortable approaching stranger
Premise (1): StrangerSimilar Age CAStranger (likely)
The second sentence contains two clauses: the first clause is the conclusion of the argument
(“therefore”), whereas the second clause is a premise (“since”):
Premise (2): Most Friendships CAStranger
Conclusion: FriendshipsSimilar Age (probably)
You should immediately recognize that this argumentation takes the form of a Mistaken Reversal:
just because age similarity is often enough to make us feel comfortable approaching a stranger does
not mean that we only approach strangers of the same approximate age. The author is confusing a
condition sufficient to guarantee a certain outcome with a condition required for that outcome to
occur. Consequently, even if most friendships begin when someone felt comfortable approaching a
stranger, it is quite possible that not all long-term friends are of the same approximate age, because
one might feel comfortable approaching a stranger who is not one’s approximate age. This prephrase
reveals answer choice (E) to be correct.
Answer choice (A): This answer choice suggests that we only feel uncomfortable approaching
strangers:
Uncomfortable Stranger
Clearly, this is not an assumption upon which the argument depends. Even if we sometimes feel
uncomfortable approaching people who are not strangers, this would not undermine the validity of
the conclusion. Hence, the author does not presume the statement in this answer choice to be true.
Answer choice (B): The author does not conflate the occurrence of a characteristic in most situations
with its occurrence in a particular situation. The characteristic in question (same approximate age) is
qualified by such terms as “likely,” “probably,” and “most” throughout the argument.
Answer choice (C): The comparative likelihood of approaching strangers vs. non-strangers whose
age is similar to ours has no bearing on whether most long-term friends are the same age as each
other. Even if one finds it easier to approach a non-stranger who ultimately becomes a long-term
friend, the two friends would still be of the same approximate age.
Answer choice (D): This is an attractive, but ultimately incorrect, description of the logical flaw in
this argument. Because the statement in it is phrased as an assumption (“presumes, without warrant,
that…”) there is an easy way to test if it is indeed something upon which the argument depends.
Apply the Assumption Negation technique and ask yourself whether the logical opposite of this
statement weakens the conclusion of the argument:
One sometimes approaches strangers even if one does not feel
comfortable doing so.
This statement would neither support nor weaken the conclusion of the argument, because merely
approaching strangers is not something that necessarily leads to long-term friendships; feeling
comfortable approaching a stranger does. So even if we sometimes approach strangers without
feeling comfortable doing so, and these strangers are not of our own approximate age, there is no
evidence that they would ever become life-long friends. Since the logical opposite of the statement
described in this answer choice does not weaken the conclusion of the argument, this statement is not
an assumption upon which the argument depends.
Answer choice (E): This is the correct answer choice. Based on the initial premise, it is entirely
possible that feels comfortable approaching a stranger who is not one’s approximate age. If a
friendship begins (as most friendships do), the friends would not be of the same approximate age as
each other, which directly undermines the conclusion of the argument.
Note that there are multiple ways to describe the same flaw in conditional reasoning. Compare the
following examples, all of which amount to the same description of a Mistaken Reversal:
The author treats something that is sufficient for bringing about a state of affairs as
something that is necessary to bring about that state of affairs.
From the assertion that something is often sufficient for a long-term friendship to
occur, the author concludes that the same thing is necessary for such friendships to
occur.
The author takes for granted that one is likely to feel comfortable approaching a
stranger only if the stranger is of one’s approximate age.
Because there are so many ways to describe a conditional reasoning flaw, it is important to prephrase
an answer describing a Mistaken Reversal but keep an open mind—do not let yourself get “boxed in”
the exact language of your prephrase.
Flaw in the Reasoning. The correct answer choice is (E)
We tend to approach strangers if the stranger is of our own approximate age, and most long-term
friendships begin by approaching a stranger. On that basis, the author considers it likely that longterm
friends are of the same approximate age.
It may be helpful to diagram the argument contained in the stimulus as if it contained conditional
reasoning. However, keep in mind that the relationships in each premise are less than absolute, due to
the use of such phrases as “likely,” “probably,” and “most.” Nevertheless, since our primary objective
is to understand the logical structure of the argument as clearly as possible, such a conditional
approach would be justified, albeit with a caveat.
The first premise of the argument can be diagrammed as follows:
StrangerSimilar Age = One is of a similar age as a stranger
CAStranger = Comfortable approaching stranger
Premise (1): StrangerSimilar Age CAStranger (likely)
The second sentence contains two clauses: the first clause is the conclusion of the argument
(“therefore”), whereas the second clause is a premise (“since”):
Premise (2): Most Friendships CAStranger
Conclusion: FriendshipsSimilar Age (probably)
You should immediately recognize that this argumentation takes the form of a Mistaken Reversal:
just because age similarity is often enough to make us feel comfortable approaching a stranger does
not mean that we only approach strangers of the same approximate age. The author is confusing a
condition sufficient to guarantee a certain outcome with a condition required for that outcome to
occur. Consequently, even if most friendships begin when someone felt comfortable approaching a
stranger, it is quite possible that not all long-term friends are of the same approximate age, because
one might feel comfortable approaching a stranger who is not one’s approximate age. This prephrase
reveals answer choice (E) to be correct.
Answer choice (A): This answer choice suggests that we only feel uncomfortable approaching
strangers:
Uncomfortable Stranger
Clearly, this is not an assumption upon which the argument depends. Even if we sometimes feel
uncomfortable approaching people who are not strangers, this would not undermine the validity of
the conclusion. Hence, the author does not presume the statement in this answer choice to be true.
Answer choice (B): The author does not conflate the occurrence of a characteristic in most situations
with its occurrence in a particular situation. The characteristic in question (same approximate age) is
qualified by such terms as “likely,” “probably,” and “most” throughout the argument.
Answer choice (C): The comparative likelihood of approaching strangers vs. non-strangers whose
age is similar to ours has no bearing on whether most long-term friends are the same age as each
other. Even if one finds it easier to approach a non-stranger who ultimately becomes a long-term
friend, the two friends would still be of the same approximate age.
Answer choice (D): This is an attractive, but ultimately incorrect, description of the logical flaw in
this argument. Because the statement in it is phrased as an assumption (“presumes, without warrant,
that…”) there is an easy way to test if it is indeed something upon which the argument depends.
Apply the Assumption Negation technique and ask yourself whether the logical opposite of this
statement weakens the conclusion of the argument:
One sometimes approaches strangers even if one does not feel
comfortable doing so.
This statement would neither support nor weaken the conclusion of the argument, because merely
approaching strangers is not something that necessarily leads to long-term friendships; feeling
comfortable approaching a stranger does. So even if we sometimes approach strangers without
feeling comfortable doing so, and these strangers are not of our own approximate age, there is no
evidence that they would ever become life-long friends. Since the logical opposite of the statement
described in this answer choice does not weaken the conclusion of the argument, this statement is not
an assumption upon which the argument depends.
Answer choice (E): This is the correct answer choice. Based on the initial premise, it is entirely
possible that feels comfortable approaching a stranger who is not one’s approximate age. If a
friendship begins (as most friendships do), the friends would not be of the same approximate age as
each other, which directly undermines the conclusion of the argument.
Note that there are multiple ways to describe the same flaw in conditional reasoning. Compare the
following examples, all of which amount to the same description of a Mistaken Reversal:
The author treats something that is sufficient for bringing about a state of affairs as
something that is necessary to bring about that state of affairs.
From the assertion that something is often sufficient for a long-term friendship to
occur, the author concludes that the same thing is necessary for such friendships to
occur.
The author takes for granted that one is likely to feel comfortable approaching a
stranger only if the stranger is of one’s approximate age.
Because there are so many ways to describe a conditional reasoning flaw, it is important to prephrase
an answer describing a Mistaken Reversal but keep an open mind—do not let yourself get “boxed in”
the exact language of your prephrase.