This is an NA question.

The stimulus proceeds in order from premises to the conclusion. Bovine remains were found in a certain place back when that place had an arid (dry) climate. There were people present at that time in that region but no other large mammals. If there were natural sources of water available, there would also have been other large mammals. But we already know there were no other large mammals. We can contrapose to infer that there were no natural sources of water available.

The argument hence concludes that these bovines had been domesticated (people were providing it water) and the people there were no longer exclusively hunter-gatherers.

This sounds like a decent argument, right? If you think so, then you’re already supplying the missing assumption, that if they weren’t domesticated, they couldn’t have survived. But really, we don’t know that. Perhaps they were wild and crafty and survived by taking advantage of man-made water sources. That would be bad for the argument. So we do need to supply the assumption connecting the premises (arid climate, no natural water sources) to the conclusion (domestication).

This is what Correct Answer Choice (A) does. Translating the “unless,” (A) says that if the bovines weren’t domesticated, they were unlikely to exist in a region without natural sources of water. The premises fail the necessary condition (the bovines likely did exist), which allows us to infer the failure of the sufficient condition (the bovines were domesticated) as the conclusion. This connects the premises to the conclusion. More than that, it truly is necessary. If we deny this conditional relationship, we’re asserting that it’s possible for the bovines to be wild yet survive anyway in this arid region. That’s exactly the possibility that we contemplated above that would ruin the argument.

Answer Choice (B) says that domesticating animals is one of the first things that a society must do when transitioning from hunter-gatherer to agriculture. This is unnecessary. Why first? Why not second or third? Also notice that it’s trying to bridge the two concepts in the conclusion, that of “domestication” and that of “no longer exclusively hunter-gatherer.” But we don’t need to build that bridge. They are already connected by their definitions. Domestication necessarily implies no longer exclusively hunter-gatherer. A culture that practices domestication cannot be exclusively hunter-gatherer.

Answer Choice (C) says that other large mammals would have been able to inhabit this arid region with the help of humans. So, like what? Horses? That’s required? No, it’s not. Let’s imagine this were false. Even with the help of humans, this arid region could not have supported horses. Who cares? The argument is still as strong as it ever was.

Answer Choice (D) says no human culture can be a hybrid of agriculture and hunter-gatherer. So (D) is claiming that all human cultures must be exclusively either an agricultural society or else a hunter-gatherer society. You can’t do both. But that’s silly. It doesn’t affect the argument if there was a culture that both planted wheat and hunted meat. In fact, the conclusion in the stimulus claims that these people are a kind of hybrid culture.

Answer Choice (E) says that a domesticated cow doesn’t need as much water as a wild cow. This might strengthen the argument? Like their modest demand for water might help explain why humans were able to domesticate them in an arid climate. But it’s not necessary. Imagine this were false and the cows required the same amount of water, regardless of whether they were domesticated or wild. The argument would still be fine. It would just have been not as easy to domesticate them.


6 comments

This is an NA question.

The argument begins with a pretty long sentence that turns out to be just context. It tells us similarities between the “chorus” in a play and the “narrator” in a novel. They share many similarities. Both introduce a point of view untied to other characters. Both allow the author to comment on the characters’ actions and to introduce other information.

With the word “however,” we transition from context to argument. And it’s a simple argument with one premise and one conclusion. The premise is that the chorus sometimes introduces information inconsistent with the rest of the play. The conclusion is that the chorus is not equivalent to the narrator.

What’s the missing link? It’s a premise-to-conclusion bridge. We have to assume that the narrator never introduces inconsistent information.

This is what Correct Answer Choice (D) provides. It says that information introduced by a narrator can never be inconsistent with the rest of the information in the novel. That’s it. And with this assumption, the argument is valid. This is an example of where a necessary assumption is also a sufficient assumption. This tends to happen when the argument structure is simple and therefore there is only one assumption to bridge the premise to the conclusion.

Answer Choice (A) is attractive. It says the narrator is never deceptive. This sounds necessary, right? Because the premise said the chorus was deceptive and so in order for the narrator to not be equivalent with the chorus, it must be that the narrator is never deceptive. But no, this isn’t necessary. The premise just said that the chorus sometimes introduces information that’s inconsistent with the rest of the play. That doesn’t mean the chorus is being deceptive. We’re projecting intent onto the chorus without evidence. Maybe they’re trying to deceive. Maybe they’re trying to help us see through the deception of a character in the play. The chorus is telling the truth to the character’s lies. So no, (A) is not necessary. The narrator can be deceptive and the conclusion can still follow that the narrator is not equivalent to the chorus.

This also explains why Answer Choice (E) is unnecessary. (E) claims that authors sometimes use choruses to mislead audiences.

Answer Choice (B) says the voice of a narrator is sometimes necessary in plays that employ a chorus. What? Get out of here with this basic BS. This is just a mish-mash of ideas from the stimulus. There’s no reason why a play that employs a chorus must also employ a narrator.

Answer Choice (C) claims that information necessary for the audience to understand the events in a play is sometimes introduced by the chorus. No, this isn’t necessary. Let’s say that all the information introduced by the chorus is “extra” information: nice to have but not required for the audience to understand the play. What impact would that have on the argument? Not much. The narrator can still be not equivalent to the chorus as long as the narrator does what (D) says.


1 comment

This is an NA question.

The argument begins with a pretty long sentence that turns out to be just context. It tells us similarities between the “chorus” in a play and the “narrator” in a novel. They share many similarities. Both introduce a point of view untied to other characters. Both allow the author to comment on the characters’ actions and to introduce other information.

With the word “however,” we transition from context to argument. And it’s a simple argument with one premise and one conclusion. The premise is that the chorus sometimes introduces information inconsistent with the rest of the play. The conclusion is that the chorus is not equivalent to the narrator.

What’s the missing link? It’s a premise-to-conclusion bridge. We have to assume that the narrator never introduces inconsistent information.

This is what Correct Answer Choice (D) provides. It says that information introduced by a narrator can never be inconsistent with the rest of the information in the novel. That’s it. And with this assumption, the argument is valid. This is an example of where a necessary assumption is also a sufficient assumption. This tends to happen when the argument structure is simple and therefore there is only one assumption to bridge the premise to the conclusion.

Answer Choice (A) is attractive. It says the narrator is never deceptive. This sounds necessary, right? Because the premise said the chorus was deceptive and so in order for the narrator to not be equivalent with the chorus, it must be that the narrator is never deceptive. But no, this isn’t necessary. The premise just said that the chorus sometimes introduces information that’s inconsistent with the rest of the play. That doesn’t mean the chorus is being deceptive. We’re projecting intent onto the chorus without evidence. Maybe they’re trying to deceive. Maybe they’re trying to help us see through the deception of a character in the play. The chorus is telling the truth to the character’s lies. So no, (A) is not necessary. The narrator can be deceptive and the conclusion can still follow that the narrator is not equivalent to the chorus.

This also explains why Answer Choice (E) is unnecessary. (E) claims that authors sometimes use choruses to mislead audiences.

Answer Choice (B) says the voice of a narrator is sometimes necessary in plays that employ a chorus. What? Get out of here with this basic BS. This is just a mish-mash of ideas from the stimulus. There’s no reason why a play that employs a chorus must also employ a narrator.

Answer Choice (C) claims that information necessary for the audience to understand the events in a play is sometimes introduced by the chorus. No, this isn’t necessary. Let’s say that all the information introduced by the chorus is “extra” information: nice to have but not required for the audience to understand the play. What impact would that have on the argument? Not much. The narrator can still be not equivalent to the chorus as long as the narrator does what (D) says.


2 comments

This is an NA question.

The stimulus opens with context that the premises call upon with a referential phrase. To establish a human colony on Mars, it requires the presence of a tremendous quantity of basic materials on Mars. And then we need to assemble those materials. The premise states that the costs of transporting those materials through space would be very high. Therefore, the argument concludes that it wouldn’t be economically feasible to establish a colony on Mars.

The assumption is that the costs in the premises are a consideration that matters. What are those costs again? Costs of “transporting material through space.” Now, why would we need to transport materials through space? Because a Martian colony requires a tremendous amount of basic materials. But again, why must we transport that “tremendous amount of basic materials” through space? The assumption is that those materials cannot be found on Mars.

This is absolutely necessary for the premises to even matter to the conclusion. This is what Correct Answer Choice (E) says. That Mars isn’t a practical source of the basic materials required for establishing human habitation there. If Mars were, then there’d be no need to transport those materials through space.

(E) seems pretty obvious once you get there. But the hard part is in getting past the other trap answers.

Answer Choice (A) is one such trap. It uses “only if” to lay out a necessary condition for establishing human habitation on Mars: the decrease in cost of transporting materials from Earth to Mars. This sounds good but it isn’t necessary. First, note that the conclusion didn’t claim that it would be physically impossible to colonize Mars. Rather, just that it would be economically infeasible. Economically infeasible means highly unlikely, but it doesn’t mean impossible. Economic constraints are softer than physical or technological constraints. Economic constraints are a matter of collective resource allocation. Physical or technological constraints are imposed by what knowledge we have access to. Second, note that the premises cited the costs of transportation through space. Surely Earth to Mars is through space but so is the moon to Mars. And so is the asteroid belt to Mars. If the materials aren’t even coming from Earth in the first place, then why should we care about the transportation costs of Earth to Mars?

Answer Choice (B) is another trap. It says that the cost of transportation through space (note already the improvement upon (A)) isn’t expected to decrease in the near future. Again, this sounds good. Don’t we need the costs to not decrease? Well, first notice that (B) isn’t about what will actually happen to the costs. It’s about what we expect to happen to the costs. We don’t need expectations to point in any particular direction. We need actual costs to not decrease. Second, even if actual costs decrease in the near future, the argument can still survive as long as the costs don’t decrease too much. For example, imagine if the costs decrease by 0.01%. That’s presumably not enough of a decrease to make a difference. In order to hurt the argument, we need to have the costs decrease to the point of being economically feasible to transport enough basic materials to Mars.

Answer Choice (C) claims that Earth is the only source of basic materials necessary for a Martian colony. This is a classic Strengthen answer in an NA question. If (C) were true, then that definitely helps the argument. Earth is the only source of raw materials and therefore, to get those materials to Mars, we must transport them through space. But this isn’t necessary. What if one of Mars' two moons had the requisite materials? That would still require transportation through space and so the argument would still survive. (C) isn’t necessary.

Answer Choice (D) says that no significant benefit would result from establishing a human colony on Mars. This isn’t necessary. The argument didn’t express a value judgment. It wasn’t about the pros and cons of establishing a Mars colony or whether we should do it. It was just an argument about the costs and economic feasibility of such an endeavor. (D) is not only unnecessary, it is also irrelevant.


9 comments

This is an NA question.

The stimulus opens with context that the premises call upon with a referential phrase. To establish a human colony on Mars, it requires the presence of a tremendous quantity of basic materials on Mars. And then we need to assemble those materials. The premise states that the costs of transporting those materials through space would be very high. Therefore, the argument concludes that it wouldn’t be economically feasible to establish a colony on Mars.

The assumption is that the costs in the premises are a consideration that matters. What are those costs again? Costs of “transporting material through space.” Now, why would we need to transport materials through space? Because a Martian colony requires a tremendous amount of basic materials. But again, why must we transport that “tremendous amount of basic materials” through space? The assumption is that those materials cannot be found on Mars.

This is absolutely necessary for the premises to even matter to the conclusion. This is what Correct Answer Choice (E) says. That Mars isn’t a practical source of the basic materials required for establishing human habitation there. If Mars were, then there’d be no need to transport those materials through space.

(E) seems pretty obvious once you get there. But the hard part is in getting past the other trap answers.

Answer Choice (A) is one such trap. It uses “only if” to lay out a necessary condition for establishing human habitation on Mars: the decrease in cost of transporting materials from Earth to Mars. This sounds good but it isn’t necessary. First, note that the conclusion didn’t claim that it would be physically impossible to colonize Mars. Rather, just that it would be economically infeasible. Economically infeasible means highly unlikely, but it doesn’t mean impossible. Economic constraints are softer than physical or technological constraints. Economic constraints are a matter of collective resource allocation. Physical or technological constraints are imposed by what knowledge we have access to. Second, note that the premises cited the costs of transportation through space. Surely Earth to Mars is through space but so is the moon to Mars. And so is the asteroid belt to Mars. If the materials aren’t even coming from Earth in the first place, then why should we care about the transportation costs of Earth to Mars?

Answer Choice (B) is another trap. It says that the cost of transportation through space (note already the improvement upon (A)) isn’t expected to decrease in the near future. Again, this sounds good. Don’t we need the costs to not decrease? Well, first notice that (B) isn’t about what will actually happen to the costs. It’s about what we expect to happen to the costs. We don’t need expectations to point in any particular direction. We need actual costs to not decrease. Second, even if actual costs decrease in the near future, the argument can still survive as long as the costs don’t decrease too much. For example, imagine if the costs decrease by 0.01%. That’s presumably not enough of a decrease to make a difference. In order to hurt the argument, we need to have the costs decrease to the point of being economically feasible to transport enough basic materials to Mars.

Answer Choice (C) claims that Earth is the only source of basic materials necessary for a Martian colony. This is a classic Strengthen answer in an NA question. If (C) were true, then that definitely helps the argument. Earth is the only source of raw materials and therefore, to get those materials to Mars, we must transport them through space. But this isn’t necessary. What if one of Mars' two moons had the requisite materials? That would still require transportation through space and so the argument would still survive. (C) isn’t necessary.

Answer Choice (D) says that no significant benefit would result from establishing a human colony on Mars. This isn’t necessary. The argument didn’t express a value judgment. It wasn’t about the pros and cons of establishing a Mars colony or whether we should do it. It was just an argument about the costs and economic feasibility of such an endeavor. (D) is not only unnecessary, it is also irrelevant.


12 comments

This is an NA question.

This is a very difficult argument to understand substantively. Let’s first approach this question by breaking it up into its parts. Conveniently, it progresses in order from minor premise to major premise to main conclusion. The two conclusion indicator words “thus” and “therefore” help us recognize this.

There may be a way to get to the right answer without fully understanding the argument substantively, but I wouldn’t bank on it. You’ll have to pick up in the main conclusion the new reference to “other characteristics.” What other characteristics? We’ve only talked about a star’s brightness. So the “other characteristics,” whatever they may be, had better be determinable.

If you picked up on that, then you’re probably down to Answer Choice (B) and Correct Answer Choice (D). The problem with (B) is that it’s too specific and hence unnecessary. We don’t need “differences in the elements each is burning” to be detectable from Earth. We just need some difference to be detectable from Earth, like how (D) has it.

Okay, but let’s back up and try to actually understand this argument.

The minor premise tells us that the distance between Earth and a distant galaxy overwhelms the distance between Earth and any object in that distant galaxy. Imagine you’re on a tiny island and we’re trying to measure the distance between you and two people on a different faraway tiny island. They’re not equidistant from you. One of them is actually closer, because, say, one is standing at the shore and the other is standing on the other side of the island. But the first sentence is saying that the distance between the two islands is so vast that that’s the only thing that really matters. The islands themselves are so small and the vast space between the islands so large that it hardly matters where anyone is standing on their islands. That difference is so small that it’s negligible.

So it follows that if two stars are in the same distant galaxy (two people on the same distant island), then the distance between those two stars to Earth will in effect be the same (because whatever difference is negligible). But if we still observe a difference in their brightness, that difference can’t be due to their (negligibly different) distance. It must be due to their actual brightness as in how bright they’re actually burning and not just how bright they appear to be.

Now the argument reaches for its main conclusion. It concludes that we should be able to figure out the correlation between two stars' relative actual brightness and the two stars’ other characteristics. We see “other characteristics” appear out of nowhere. We did talk about brightness and how if two stars are in the same distant galaxy, we can in effect treat them as being equidistant from Earth in terms of their brightness. But in order to correlate their brightness with “other characteristics,” we first have to be able to detect and measure those “other characteristics.”

Again, this is what Correct Answer Choice (D) picks up on. It says that there are stars in distant galaxies that have characteristics, other than brightness, discernible from Earth. This must be true. If this were false, that would mean that we could discern only a distant star’s brightness and nothing else. If that’s true, then we would be unable to correlate brightness with anything else.

Note that (D) doesn’t care to specify what the “characteristics” are. That’s good because the conclusion didn’t care to specify either. This is what makes Answer Choice (B) unnecessary. While (B) would certainly strengthen the argument, we don’t need the differences in the elements each is burning to be detectable from Earth. Who knows what “other characteristics” the conclusion wanted to correlate with brightness? Maybe it’s the elements that each is burning. Maybe it’s the color of the stars, their size or mass, or their temperature. It could be any of those characteristics that need to be detectable from Earth.

Answer Choice (A) says that if two stars are in two different galaxies... Eh, we can stop. We don’t care. The argument cares about two stars in the same distant galaxy. (A) talks about two stars in two different (near or far?) galaxies. Whatever else (A) is about to say for these two stars will be irrelevant so you should move on to the next answer.

But for review, we can negate this and see that it has no impact on the argument. So what if it is possible to determine their distances from Earth? That doesn’t hurt the argument.

Answer Choice (C) is similarly irrelevant for it talks about stars in our own galaxy. Again, for the same reasons as in (A), we don’t care. We should move on.

If we negate (C), that’s just fine for the argument. It would be absolutely bizarre if all the stars in the Milky Way were all approximately the same distance from Earth but it wouldn’t affect the argument.

Answer Choice (E) can also be similarly eliminated as soon as you see that it’s talking about stars that are significantly different in distance from Earth. The argument contemplated two stars that are not significantly different in distance from Earth. That’s what the sub-argument established by placing the two stars in distant galaxies to begin with. We should move on.

(E) goes on to say that if there are significant differences in how far away two stars are from Earth, then those stars will differ significantly in apparent brightness. This isn’t required. It’s fine for the argument if two stars of significant difference in distance from Earth are about the same in brightness. The argument contemplated two stars of insignificant difference in distance but significant difference in brightness. After all, a major assumption of the argument is that distance is only one factor in determining a star’s brightness.


6 comments

This is an NA question.

This is a very difficult argument to understand substantively. Let’s first approach this question by breaking it up into its parts. Conveniently, it progresses in order from minor premise to major premise to main conclusion. The two conclusion indicator words “thus” and “therefore” help us recognize this.

There may be a way to get to the right answer without fully understanding the argument substantively, but I wouldn’t bank on it. You’ll have to pick up in the main conclusion the new reference to “other characteristics.” What other characteristics? We’ve only talked about a star’s brightness. So the “other characteristics,” whatever they may be, had better be determinable.

If you picked up on that, then you’re probably down to Answer Choice (B) and Correct Answer Choice (D). The problem with (B) is that it’s too specific and hence unnecessary. We don’t need “differences in the elements each is burning” to be detectable from Earth. We just need some difference to be detectable from Earth, like how (D) has it.

Okay, but let’s back up and try to actually understand this argument.

The minor premise tells us that the distance between Earth and a distant galaxy overwhelms the distance between Earth and any object in that distant galaxy. Imagine you’re on a tiny island and we’re trying to measure the distance between you and two people on a different faraway tiny island. They’re not equidistant from you. One of them is actually closer, because, say, one is standing at the shore and the other is standing on the other side of the island. But the first sentence is saying that the distance between the two islands is so vast that that’s the only thing that really matters. The islands themselves are so small and the vast space between the islands so large that it hardly matters where anyone is standing on their islands. That difference is so small that it’s negligible.

So it follows that if two stars are in the same distant galaxy (two people on the same distant island), then the distance between those two stars to Earth will in effect be the same (because whatever difference is negligible). But if we still observe a difference in their brightness, that difference can’t be due to their (negligibly different) distance. It must be due to their actual brightness as in how bright they’re actually burning and not just how bright they appear to be.

Now the argument reaches for its main conclusion. It concludes that we should be able to figure out the correlation between two stars' relative actual brightness and the two stars’ other characteristics. We see “other characteristics” appear out of nowhere. We did talk about brightness and how if two stars are in the same distant galaxy, we can in effect treat them as being equidistant from Earth in terms of their brightness. But in order to correlate their brightness with “other characteristics,” we first have to be able to detect and measure those “other characteristics.”

Again, this is what Correct Answer Choice (D) picks up on. It says that there are stars in distant galaxies that have characteristics, other than brightness, discernible from Earth. This must be true. If this were false, that would mean that we could discern only a distant star’s brightness and nothing else. If that’s true, then we would be unable to correlate brightness with anything else.

Note that (D) doesn’t care to specify what the “characteristics” are. That’s good because the conclusion didn’t care to specify either. This is what makes Answer Choice (B) unnecessary. While (B) would certainly strengthen the argument, we don’t need the differences in the elements each is burning to be detectable from Earth. Who knows what “other characteristics” the conclusion wanted to correlate with brightness? Maybe it’s the elements that each is burning. Maybe it’s the color of the stars, their size or mass, or their temperature. It could be any of those characteristics that need to be detectable from Earth.

Answer Choice (A) says that if two stars are in two different galaxies... Eh, we can stop. We don’t care. The argument cares about two stars in the same distant galaxy. (A) talks about two stars in two different (near or far?) galaxies. Whatever else (A) is about to say for these two stars will be irrelevant so you should move on to the next answer.

But for review, we can negate this and see that it has no impact on the argument. So what if it is possible to determine their distances from Earth? That doesn’t hurt the argument.

Answer Choice (C) is similarly irrelevant for it talks about stars in our own galaxy. Again, for the same reasons as in (A), we don’t care. We should move on.

If we negate (C), that’s just fine for the argument. It would be absolutely bizarre if all the stars in the Milky Way were all approximately the same distance from Earth but it wouldn’t affect the argument.

Answer Choice (E) can also be similarly eliminated as soon as you see that it’s talking about stars that are significantly different in distance from Earth. The argument contemplated two stars that are not significantly different in distance from Earth. That’s what the sub-argument established by placing the two stars in distant galaxies to begin with. We should move on.

(E) goes on to say that if there are significant differences in how far away two stars are from Earth, then those stars will differ significantly in apparent brightness. This isn’t required. It’s fine for the argument if two stars of significant difference in distance from Earth are about the same in brightness. The argument contemplated two stars of insignificant difference in distance but significant difference in brightness. After all, a major assumption of the argument is that distance is only one factor in determining a star’s brightness.


12 comments

This is a Sufficient Assumption question.

The argument starts with a conditional: a thriving population of turtles in a pond requires beneficial conditions at the pond.

thriving → beneficial

Wallakim Pond, we’re told, has acidic water.

acidicw

We’re also told that Sosachi Pond doesn’t but the conclusion doesn’t care about Sosachi and so we shouldn’t either.

Finally, the conclusion says that the population of turtles at Wallakim Pond must not be thriving.

/thrivingw

Let’s put this all together.

thriving → beneficial

acidicw

_________________

/thrivingw

Looking at the conclusion, you can see that the argument is trying to contrapose on the conditional. It’s trying to fail the “beneficial” condition. If it’s successful in doing that, then we can conclude “/thriving.” But the problem is that the only other premise doesn’t hook up to “/beneficial.” We don’t know what “acidic” means for turtles. Is that beneficial for them or not? If we’re able to establish that “/acidic” is a necessary condition, then this argument becomes valid:

thriving → beneficial → /acidic

acidicw

_________________

/thrivingw

This is what Correct Answer Choice (E) gives us. It says that the conditions of a pond are beneficial only if the water is not acidic. That’s exactly what we’re looking for: beneficial → /acidic.

Answer Choice (A) says that if the water is not acidic, then the conditions are beneficial. /acidic → beneficial. That’s the sufficiency-necessity confused version of (E).

Answer Choice (B) says that the acidity of water is the most important factor that determines whether the population of turtles will be thriving. But that doesn’t tell us whether acid is good or bad. It just says it’s powerful. In which direction? Even if (B) said that it’s in the bad direction, it would merely strengthen the argument, which would still fall short of the SA requirement.

This is what we in effect get in Answer Choice (C). It says that the conditions at Sosachi are more beneficial than the conditions at Wallakim. We have to assume that all other conditions are held equal between Sosachi and Wallakim. On that assumption, we can infer that the difference is caused by the difference in their waters’ acidity. But even then, it just means that acidity is relatively less beneficial.

Answer Choice (D) says that Wallakim would have a thriving population if the water were not acidic. That translates to /acidic → thriving. But that doesn’t fit what we’re looking for.

That means it’s the acidity in the water that’s causing the population to not be thriving.


1 comment

This is a Sufficient Assumption question.

The argument starts with a conditional: a thriving population of turtles in a pond requires beneficial conditions at the pond.

thriving → beneficial

Wallakim Pond, we’re told, has acidic water.

acidicw

We’re also told that Sosachi Pond doesn’t but the conclusion doesn’t care about Sosachi and so we shouldn’t either.

Finally, the conclusion says that the population of turtles at Wallakim Pond must not be thriving.

/thrivingw

Let’s put this all together.

thriving → beneficial

acidicw

_________________

/thrivingw

Looking at the conclusion, you can see that the argument is trying to contrapose on the conditional. It’s trying to fail the “beneficial” condition. If it’s successful in doing that, then we can conclude “/thriving.” But the problem is that the only other premise doesn’t hook up to “/beneficial.” We don’t know what “acidic” means for turtles. Is that beneficial for them or not? If we’re able to establish that “/acidic” is a necessary condition, then this argument becomes valid:

thriving → beneficial → /acidic

acidicw

_________________

/thrivingw

This is what Correct Answer Choice (E) gives us. It says that the conditions of a pond are beneficial only if the water is not acidic. That’s exactly what we’re looking for: beneficial → /acidic.

Answer Choice (A) says that if the water is not acidic, then the conditions are beneficial. /acidic → beneficial. That’s the sufficiency-necessity confused version of (E).

Answer Choice (B) says that the acidity of water is the most important factor that determines whether the population of turtles will be thriving. But that doesn’t tell us whether acid is good or bad. It just says it’s powerful. In which direction? Even if (B) said that it’s in the bad direction, it would merely strengthen the argument, which would still fall short of the SA requirement.

This is what we in effect get in Answer Choice (C). It says that the conditions at Sosachi are more beneficial than the conditions at Wallakim. We have to assume that all other conditions are held equal between Sosachi and Wallakim. On that assumption, we can infer that the difference is caused by the difference in their waters’ acidity. But even then, it just means that acidity is relatively less beneficial.

Answer Choice (D) says that Wallakim would have a thriving population if the water were not acidic. That translates to /acidic → thriving. But that doesn’t fit what we’re looking for.

That means it’s the acidity in the water that’s causing the population to not be thriving.


2 comments

This is an NA question.

The editorial begins with a premise that last year, many polls found that most people in the country say that they’re tired of celebrity gossip on TV news and that they’re not willing to watch them anymore. But last year’s ratings for TV news soared.

Okay, so something’s not quite adding up. But what is it? At this point in the stimulus, it resembles an RRE, doesn’t it? What’s going on? How can both of these claims be true?

Well, the editorial thinks (concludes) that often people portray themselves as they wish to be perceived, rather than as they actually are, whether or not they’re aware of it.

That could be the explanation. But in order for that to be the explanation, the argument must assume at least two things.

First, we know that somebody's watching those shows otherwise the ratings couldn’t have soared. And it’s a lot of somebodies. In order for the conclusion to follow, we have to assume that at least some of those same people who responded to the polls saying they’re sick of the shows and don’t want to watch them anymore ended up watching anyway. There must be at least some overlap between the set of people who say they don’t want to watch and the set of people who watched. If there’s no overlap, then that means everyone who ended up watching either didn’t respond to the polls or responded to the polls saying they wanted to watch. If that’s the case, then the conclusion cannot be supported on these premises. The argument falls apart.

But even with this first assumption, the conclusion still doesn’t yet follow. What does follow is that often people say one thing and do another. In other words, people are often hypocritical. But that’s not what the actual conclusion says. The actual conclusion says that people often “portray themselves as they wish to be perceived.” Where did that come from? Is being sick of those shows how they “wish to be perceived” or were they simply answering the poll questions without regard to how they “wish to be perceived”? If I tell you I don’t like ice cream, you can’t automatically assume that I wish to be perceived as someone who doesn’t like ice cream. Perhaps I’m just telling you that I don’t like ice cream and the thought never occurred to me that it would make me look bad. Seriously, what kind of degenerate doesn’t like ice cream? That’s the second assumption. At least some people who told the polls that they’re sick of the shows and don’t want to watch them anymore wish to be perceived as being sick of the shows and not wanting to watch anymore.

These two assumptions show up in Answer Choice (B) and Correct Answer Choice (E).

(B) goes after the first assumption and says that last year, “almost everyone” who said they’re sick of the shows and unwilling to watch anymore continued to watch. This is really helpful for the argument. But it’s not necessary. We don’t need “almost everyone.” We just need “some” people. Think about what “almost everyone” means. Yeah, it’s ambiguous but that doesn’t mean it has no obviously right and wrong interpretations. 95% would obviously be “almost everyone” and 60% would obviously not be “almost everyone.” But if it is in fact the case that 60% of those who said they’re sick of the shows yet watched anyway, then it's still really good for the argument. It’s not as good as 95% but it’s still good. That demonstrates (B) as unnecessary.

(E) goes after the second assumption and says that last year, “at least some” people who responded to the polls wished to be perceived as unwilling to watch the shows. That’s exactly right. If this were false, then that means nobody who responded to the polls wished to be perceived as unwilling to watch the shows. That would render the conclusion unsupportable on the basis of the premises.

Answer Choice (A) can be eliminated because of “everyone.” That’s even more unnecessary than “almost everyone” in (B). There’s another problem. (A) is trying to say that there must be an overlap between people who said they’re sick of the shows and people who said they’re unwilling to watch the shows. That’s not necessary. What we actually need is an overlap between either of those two sets with the set of people who in fact watched the shows.

Answer Choice (C) says “at least some,” which is good. The rest of it is not. (C) says at least some people who responded to the polls don’t believe that in their responses they’re portraying themselves as they actually were. In other words, some people were intentionally misrepresenting themselves through their response. Do we need that to be true? No. It’s fine if no one intentionally misrepresented themselves. They still could have unintentionally misrepresented themselves. The conclusion accommodated this already when it said “whether or not they’re aware of it.”

Answer Choice (D) says “no one” who responded to the polls portrayed themselves as they actually were. So everyone misrepresented themselves, whether they meant to or not. We don’t need this either. The argument doesn’t care if half of the people misrepresented themselves.


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