Q11 - Logging industry official: Harvesting

[aidanmenzul]

I'm not quite sure why C can't be the right answer or why B is because it doesn't seem to address the second half of the question.

[ManhattanPrepLSAT1]

A good understanding of your task on weakening questions might help. Your task is to undermine the conclusion of the argument. Many people lose sight of the task and focus too much on the evidence.

Answer choice (B) would undermine the argument because if old-growth trees were turned into products that decomposed rapidly, then all of that carbon dioxide stored in that material would be released. Thus, while the young trees might absorb more carbon dioxide, the net effect would undetermined.

Answer choice (C) doesn't undermine the argument, because all it tells us is that there is a great deal of carbon dioxide in old-growth trees relative to young trees. But it doesn't tell us whether that carbon dioxide would be released into the atmosphere.

I think if you're focused on the conclusion, you'll have an easier time weakening and strengthening arguments.

Does that help clear this one up? If not, let me know. I'd be happy to keep working through this one with you.

[aidanmenzul]

Thanks.. It helps. Focusing on the conclusion definitely helps not get side tracked with all of the fluff material in the question... I just need to remember to do it.

[geverett]

I just did this question and was more stuck between B and D. Here are some of the things I was thinking about that helped me arrive at the right answer choice (albeit after 5 minutes of consideration) and eliminate answer choice D.

Conclusion: cutting down trees from old growth forests for use in manufacturing can cause a reduction of carbon dioxide in the atmosphere.

Premise 1: When the large trees die in the forest they decompose and release their stored carbon dioxide.

Premise 2: Harvesting of the old growth forests makes room for young trees which absorb more carbon dioxide from the atmosphere than old growth trees

We need to weaken this argument

Prephrase: Okay we have talked about a reduction of carbon dioxide released from the old growth forests that causes a reduction of carbon dioxide in the atmosphere. Could there be some kind of concomitant process whenever old growth trees are harvested that offsets the loss of carbon dioxide from the loss of those trees? I go to the answer choices with this in mind.

(A) Wrong. This would give another reason not to harvest old growth forests, and so would serve as a strengthener. It also does not approach the conclusion about a reduction of carbon dioxide in the atmosphere from harvesting of old growth trees.
(B) Right. Okay we are told that "much of the material from old growth trees not used in the manufacturing process decomposes quickly"
Remember in weaken and strengthen questions we only need to weaken or strengthen the argument by a little bit or a lot. Anywhere from 1-100% to qualify as a weaken or strengthen answer. This answer gives us reason to reconsider the argument because it's basically saying that some of the material in the old growth trees still releases carbon dioxide. Is it enough to offset what is potentially being lost by not letting the entire old growth tree decompose in it's natural environment? We are not sure. But if you look back at some of the words in the stimulus that I put in bold and italics you will notice that many of the assertions in the stimulus are also intentionally ambiguous so this answer causes us to doubt the conclusion of the argument even if just a little bit.

(C) We are not really sure what this does. Will this tree grow up and have as much carbon dioxide when it is as old as the old growth tree? We don't know. Are most of the young trees that are replacing the old growth trees members of species whose carbon dioxide levels never reach the same amount as the trees they are replacing? We have no idea. This answer choice affects nothing in it's present form.

(D) This answer choice strengthens the argument. If much of the carbon dioxide present in the forests is released when wood and other organic debris found on the forest floor decompose then the fact that the logging industry is removing some old growth trees that would be potential sources of wood to decompose on the forest floor and release carbon dioxide would serve to strengthen this argument.

(E) This is wholly irrelevant. We need something that talks about how loss of old growth trees can affect carbon dioxide in the atmosphere. The length of time it takes for newly planted trees to reach the size of those in old growth forests tells us nothing about carbon dioxide levels.

[jiyoonsim]

I, too, was stuck between B and D (and got this question wrong initially ) but I took a bit different approach.

The stem says

Conclusion:
Let's use old trees for manufacturing, so we can reduce CO2.

Premise:
Once old trees die, they release CO2.
Harvesting old trees make room for young trees, which absorb CO2 better than old trees.

The assumption here is-
CO2s are released only when old trees die/decompose.
No CO2s are released from old trees once they are harvested.

Keeping these in mind, let's take a look at the answers.

D is similar with what the stem is already saying: that once old trees die, they release CO2 as they decompose.

B does weaken the assumption of the argument. B says otherwise. If B is true, that means the old tress can still release CO2 even after they are chopped down and made into some kind of manufacturing product. If this is true, what's the point of harvesting old trees and use them in manufacturing for the sake of CO2 reduction?

[soyeonjeon]

A good understanding of your task on weakening questions might help. Your task is to undermine the conclusion of the argument. Many people lose sight of the task and focus too much on the evidence.

Answer choice (B) would undermine the argument because if old-growth trees were turned into products that decomposed rapidly, then all of that carbon dioxide stored in that material would be released. Thus, while the young trees might absorb more carbon dioxide, the net effect would undetermined.

Answer choice (C) doesn't undermine the argument, because all it tells us is that there is a great deal of carbon dioxide in old-growth trees relative to young trees. But it doesn't tell us whether that carbon dioxide would be released into the atmosphere.

I think if you're focused on the conclusion, you'll have an easier time weakening and strengthening arguments.

Does that help clear this one up? If not, let me know. I'd be happy to keep working through this one with you.

I do see that B makes more logical sense because it undermines the main premise of the stimulus about CO2 being reduced. But can you help me understand precisely why A is incorrect? I thought that A could be adding a third possibility or a new consideration to take into account thereby weakening the argument?

Oh, I just spotted something. Would A be correct if "forests" were changed to "trees from old-growth forests"?

[ManhattanPrepLSAT1]

Answer choice (A) is completely irrelevant. The argument is not about whether it's a good a idea to harvest old-growth forests, but whether harvesting old-growth forests can reduce the amount of carbon dioxide in the atmosphere.

Endangered animals may be important to us, but not to the level of carbon dioxide in the atmosphere.

Hope that helps!

[WaltGrace1983]

Ya know, you might even say (D) is a premise booster. We know that when "large old trees die in the forest they decompose." (D) is just saying that that carbon dioxide is released when wood/organic debris decompose. It's not exactly the same but it is similar enough to probably warrant an elimination.

Looking at (B) again, it seems that it is basically saying that old-growth trees are made into products that also decompose rapidly. I mean, isn't a tree completely "organic matter?" Looks like LSAC was trying to throw us off!

[coco.wu1993]

I think C is a good answer. But I finally chose C because, if young tree contains less CO2 than older tree, there will be more CO2 in the atmosphere. Why am I wrong?

[maryadkins]

I'm not sure how you are getting the idea that (C) means there would be more CO2 in the atmosphere. All (C) tells us is that young trees have less CO2 than old trees. Okay...so what? Are they going to release their CO2 when they get old and have more of it? What happens to their CO2 now—presumably, they'll just keep it because we're TOLD that young trees absorb more CO2 than old trees.

Basically (C) leaves a lot unknown and therefore is not a weakener. It does not mean there is more CO2 in the atmosphere.

[Michaelbmoss]

I do not see how B can be right.

B suggests that part of the tree is being used as lumber and that the other part can decompose.

But if part of the tree is being used as lumber and thus not adding carbon dioxide to the atmosphere then there will be a decrease.

So how does B weaken the argument that there will be a decrease?

[Mab6q]

I do not see how B can be right.

B suggests that part of the tree is being used as lumber and that the other part can decompose.

But if part of the tree is being used as lumber and thus not adding carbon dioxide to the atmosphere then there will be a decrease.

So how does B weaken the argument that there will be a decrease?

Try thinking of how B weakens the reasoning underlying the argument.

The author says x so y.

In this case, the author says that trees release CO2 when they die and decompose. But if we harvest them and use them for manufacturing, the CO2 won't be released.

Thus the amount of CO2 will decrease.

If B is true, then it's not true that we will be preventing the decomposition that leads to the release of CO2. Even if, as you suggest, some of the trees are used in manufacturing as lumber, it doesn't matter because this attacks the reasoning underlying the argument. The answer choice tells us that manufacturing might not be such a great alternative after all.

[seychelles1718]

How come C does not weaken the argument when the premise tells us younger trees absorb more CO2 than older trees, and C instead states a contradictory point, saying a younger tree has less CO2 than an old tree?

I thought "absorb CO2= contain CO2." Am I overstretching the concepts?

[maryadkins]

Please see above where Matt and I both addressed this and if you're still confused let me know.