Self-paced
Logging industry official: Conclusion Harvesting trees from old-growth forests for use in manufacture can reduce the amount of carbon dioxide in the atmosphere, since Support when large old trees die in the forest they decompose, releasing their stored carbon dioxide. ██████████ ██████████ ███████ ██████ █████████ ████ ████ ███ ███████ ███████ █████ ██████ █████ ██████ ████ ██████ ███████ ████ ███ ██████████ ████ ██ █████ ██ ██████████ ████████
Net Effect
Evaluating this stimulus and the answer choices is much easier if you’ve got a keen eye for weighing factors reasoning. This is, admittedly, an advanced example of the concept, but that just makes spotting it all the more valuable. If you roll into the answer choices hunting for the net effect one, you can save tons of time and mental energy. Here’s a summary, anyway, presented through the net effect lens:
Premise 1 : When we don’t harvest trees, they add CO2 to the atmosphere.
Premise 2 : When we do harvest trees, other trees come in and take CO2 out of the atmosphere.
________
Conclusion: The overall effect of harvesting is to take CO2 out of the atmosphere.
So if we’re trying to reduce CO2, not harvesting has one bad effect and harvesting has one good effect. As in all net effect arguments, we can articulate the flaw like this:
What if there are other factors that outweigh the ones you just mentioned?
We’re anticipating answers that say “something else about harvesting trees actually adds CO2” or “something else about not harvesting trees actually removes CO2.”
11.
Which one of the following, ██ █████ ████ █████████ ███████ ███ ████████████ █████████
a
Many old-growth forests ███ ███ ████ ██ █████████ ██ ██████ ███████ ████ █████ ██ ██████████ ██ ███ ███████ ████ ██ ██ ██████████
Lol I hate to say it, but this argument doesn’t give af about the animals. The official’s conclusion is just about the impact that harvesting trees has on atmospheric CO2. If the conclusion were “harvesting trees is a good thing to do,” then (A) would be relevant.
b
Much of the ███████ ██████ ████ ██████████ ██████ ████████ ██ ███████ ██ ████ ████ ████████ ████ █████████ ████████
This addresses the argument’s net effect reasoning by introducing an additional factor that undermines its overall calculus. The official notes that trees decompose when they’re not harvested, but (B) notes that trees also decompose when they are harvested.
Rapidly puts some icing on the cake, as well, since it suggests harvested trees could introduce more CO2 into the atmosphere than they would if left to decompose naturally.
c
A young tree ████████ ████ ████ ████ ███ ██████ ██ ██████ ███████ ████ ██ ██████ ██ ██ ███ ████ ██ ███ ████ ████████
Here’s the argument’s logic, which (C) fails to weaken:
Old tree has lots of stored CO2. We remove it from the forest, presumably without releasing any CO2. Now we have room for a new tree to grow in that spot and absorb additional CO2.
That’s how it works, according to the official. On this narrative, it doesn’t matter how much young trees store compared to old trees – we’re still storing more total CO2 than we would if we just left the old tree in place.
d
Much of the ██████ ███████ ███████ ██ ███████ ██ ██████████ ████████ ████ ████ ███ █████ ███████ ██████ █████ ██ ███ ██████ █████ ██████████
(D) doesn’t really add anything new, it just provides more detail about the phenomenon the official already established – stuff left in the forest tends to decompose, releasing CO2.
e
It can take ████ █████ ███ ███ █████ ██ █ █████ ███████ ██████ ██ █████ ███ ████ ██ █████ █████ ██ ████████ ██████████ ████████
This arguably strengthens the argument. These new trees are gonna keep sucking up CO2 for a long time!
See (C) for an additional explanation about why the exact amount of CO2 young trees can absorb doesn’t impact the official’s argument much.