Q11 - Feathers recently taken from

[dan]

11. (E)
Question Type: Assumption
The author is assuming that nothing else (aside from the amount of mercury in the eaten fish) could account for the difference in the amount of mercury found in the feathers. More specifically, the author assumes that the process of preserving the old birds didn’t somehow decrease the mercury levels of the old birds’ feathers. Answer (E) expresses this assumption. Notice that when explicitly stated the assumption supports the argument: Today’s bird feathers have less mercury, and the process of preserving the old birds didn’t decrease the mercury levels in old bird feathers, so the old fish must have had less mercury. The argument depends on this italicized assumption.

(A) is very tempting because it seems to provide an alternate explanation for why today’s bird feathers have more mercury (birds back then didn’t eat as much fish), but this would actually weaken the author’s argument. Remember, we want an assumption that is necessary to the author’s argument, not one that destroys the argument.
(B) is wrong. The issue is whether the fish today have more mercury, not why they have more mercury.
(C) is irrelevant to the conclusion of the argument.
(D) is tempting, but it’s very similar to (A) in that it seems to provide an alternate explanation for why today’s bird feathers have more mercury (the old feathers were taken from birds that weren’t fully grown), but this would actually weaken the author’s argument.


#officialexplanation

[BarryM800]

I've a technical question about the expression "as ... as ...," which is used in (A): the proportion of a seabird's diet consisting of fish was not as high, on average, in the 1880s as it is today. Think I came across another question where "as ... as ..." does not simply mean two things are equal and "not as ... as ..." does not simply mean two things are unequal. I remember Patrick gave a very good summary, but I can't remember which question it was. Anyway, clearly, "not as high as," as used here, means only "less than," and precludes the meaning of "more than." But unequal itself could be either direction, i.e., more than or less than. I checked dictionaries and grammar books and only found the distinction as "equality" and "inequality." I thought this would be important especially because with necessary assumption questions we have to apply the negation test and thus we have to have a precise understanding of meaning when statements are negated. But I don't seem to be able to come up with a good rule of thumb. Thanks!

[Misti Duvall]

I've a technical question about the expression "as ... as ...," which is used in (A): the proportion of a seabird's diet consisting of fish was not as high, on average, in the 1880s as it is today. Think I came across another question where "as ... as ..." does not simply mean two things are equal and "not as ... as ..." does not simply mean two things are unequal. I remember Patrick gave a very good summary, but I can't remember which question it was. Anyway, clearly, "not as high as," as used here, means only "less than," and precludes the meaning of "more than." But unequal itself could be either direction, i.e., more than or less than. I checked dictionaries and grammar books and only found the distinction as "equality" and "inequality." I thought this would be important especially because with necessary assumption questions we have to apply the negation test and thus we have to have a precise understanding of meaning when statements are negated. But I don't seem to be able to come up with a good rule of thumb. Thanks!

I usually just think of it as a comparison. You're right that negation can be tricky, but as long as you focus on negating the quantifier (if one) or the main verb (if not), the comparison with as shouldn't change the meaning.

For ex., "my cookie is not as chocolatey as your cookie," negates to "my cookie is as chocolately as your cookie." "Some cats are as likely as birds to fly," still negates to "No cats are as likely as birds to fly."

Hope this helps!