LSAT 14 - Section 2 - Question 19

The question stem asks, “Which one of the following most accurately expresses the main point of the passage?” So, we know this must be a main conclusion question.

First off, we learn about this report that presents some sort of information. Right away I’m thinking that LR stimuli really are so predictable, as introducing the stimulus with a study or report is something we’ve seen before that can help lay out context or background information. After reading that first sentence, it looks like my prediction was right––the author is giving us the background info we need to understand the argument and its upcoming conclusion.

Pause before we move onto the next sentence, though, and let’s break the content down into its separate parts. The first sentence fragment before the comma tells us the subject matter of the report: someone wanted to explore the “likely effects” that current air pollution levels have on forest growth in North America. What two variables do we care about? just air pollution and forest growth. Where? only in North America, as far as we know now. Do we know anything else? Again, just that the study concluded something.

Now, let’s jump to the sentence fragment after the first comma (still in the first sentence). We have seen the word “since” used to indicate a premise, or a statement that leads us to our conclusion. Because we have already decided this first sentence is likely context, we need to remind ourselves that this might not be a premise leading to the author’s main conclusion, but just a stopping point on the way to getting there. Instead, this looks like its a premise for the study’s conclusion, which is likely to be different from the author’s conclusion as we have seen in other LR arguments. So, the study’s conclusion has this premise, which tells us that one reason to accept the conclusion is that nitrogen is a necessary nutrient for plant growth. Then, the study makes a conclusion about one effect of air pollution: air pollution actually deposits nitrogen on the soil (more context built into the conclusion) which (here’s the actual conclusion of the study) “probably benefits eastern forests.” To recap: All we know so far is contextual information about a study and its conclusion.

We jump right into the next sentence with “however.” That’s a cookie cutter! We’ve seen it elsewhere to indicate a shift or contrast, which can lead us to the argument of the stimulus. We keep reading and find out that another group is being introduced: European soil scientists. Before, we only knew about whoever conducted the initial study, which was on North American air pollution and forest growth. These European soil scientists, on the other hand, have concluded something new. We know now that yet another conclusion from a group distinct from the author is being presented. What we learn from this new group is that, for a specific sub-group of all forests, those saturated in sulfate and nitrate, nitrogen deposits may not be as helpful to trees as the first study led us to believe. This group actually tells us that when the ratio of nitrogen deposited to nitrogen absorbed is too high, trees begin to die. That sounds bad for the trees! Beyond that, though, how do we know if this is a premise or conclusion? Well, let’s see if it is the claim providing support or being supported. I can’t find any support for the claim in the same sentence, just a claim itself. So, it might be a premise, or a claim supporting another claim (the eventual conclusion). After reading this claim, though, I’m left wondering if this only applies to some forests. How do we know these findings apply to forest growth in North America?

The last sentence begins with another “Since!” Let’s see... does this sentence reference another individual or group’s position? As far as we can tell, no. So, it’s safe to assume this is where the author’s real position is going to come in. Plus, we’re running out of sentences. All of those clues prime me to read what follows the “since” as the author’s premise that connects the context to our main conclusion. The premise says that the European soil scientists’ finding is “likely to apply everywhere.” Not sure how or why this is true, but who cares. My end goal is not to attack this argument (although pointing out where it falls short might help us gain insight), but instead to understand its parts. So, what follows the premise is expected to be the author’s main conclusion here: that huge parts of eastern forests in North America have already and undoubtedly been affected negatively.

Let’s double check: does the rest of the stuff in the argument seem to be supporting this statement? Well, if I were to switch it around and try to use the idea that large areas of the eastern parts of North American forests have already and undoubtedly been affected negatively to support the findings of the first study, that wouldn’t make any sense at all. Now, we are certain that the claim from the second group’s findings was a premise that provided support for the main conclusion, because it didn’t have any support itself. And, well, if it were true, combined with the following premise that we can apply these findings to trees everywhere, we are much more likely to accept the conclusion.

The author took us on that journey through those seemingly different arguments to finally end up at their own conclusion, which applies findings from the second group to the geographic location that the first study was interested in. And the conclusion definitely can’t be what follows the “since” before the first comma in the last sentence, as that statement has no premise itself (remember… we didn’t know how or why it was true) and instead is used as support to arrive at the final conclusion.

Now, we know exactly what to look for in the answer choices: something that paraphrases or explicitly states the very last statement in the stimulus, that huge parts of eastern forests in North America have already and undoubtedly been affected negatively by air pollution and its nitrogen deposits.

Answer Choice (A) This is not stated or implied as any part of the argument, let alone the conclusion. First of all, the conclusion isn’t just an implication of the report cited, but instead an application of the findings of group 2 on the area the report cared about. And then beyond that, why would the author have ended their argument with a strong statement that there have already been negative effects on the forests in question if this was the author’s main conclusion? They wouldn’t have. We have no reason to think that eastern North American forests DO have that optimal ratio of nitrogen deposited and absorbed, we only have reason to think otherwise (due to the second group’s findings and the author’s premise).

Answer Choice (B) Same thing here, this isn’t stated as any part of the argument. We don’t know what the author would say about this hypothetical! That’s beyond the scope of the argument. Plus, this isn’t a Most Strongly Supported question. We just want to know what the author actually concluded, not if they might agree with this “would” statement about what things might be like if circumstances were a certain way.

Answer Choice (C) Again, not stated in the argument and seems inaccurate based on what we know. We know nothing at all about the type of analysis used by the European soil scientist group, but the author actually stated as their premise that the findings themselves are LIKELY to apply to all forests, so if anything we might use that evidence to assume the opposite of what this AC states.

Answer Choice (D) ONLY! Since when did we say this conclusion ONLY applied to the eastern forests? I’m always skeptical of strong words like ONLY, as we will need explicit evidence from the text to support anything this strong.

Correct Answer Choice (E) This is a perfect rephrase of the author’s main point! The author’s conclusion is in contrast to the findings of the first report, and this AC posits the correct relationship between air pollution and trees in eastern forests: that nitrogen posits from the air pollution are more likely to have a negative effect on forest growth than a positive one!