by timmydoeslsat Mon Aug 06, 2012 12:44 pm
This is a classic weaken EXCEPT question with a correlation-causation issue. Same thing can happen with strengthen EXCEPT as well.
In the stimulus we are told that a new pesticide (X) was used in a pear orchard. During the three years that this pesticide was used, a lower proportion of fruit was lost to insects than during the three year period in which another pesticide (Y) was used previously. The conclusion of this argument is that X is more effective in the realm of losing fruit to insects.
This is coninciding of events, a correlation, could be explained in a multitude of ways based on the evidence given. To weaken the causal argument, we want to think what in fact weakens causation.
A) This does nothing for us. We were talking about proportions, so the overall amount does not damage anything in the argument.
B) Alternative cause. What if it were the case that during the period of pesticide X being used, there was an insect assault campaign. That could have been what caused the fruit to have not been harmed by the insects, maybe the insects were lessened due to this campaign that is unrelated to the pesticide used.
C) Alternative cause. What if the predatory birds that go after these insects are becoming more common in the area. That could explain why insects are becoming less of a problem to the fruit.
D) Alternative cause. What if the insects are losing their habitat and can no longer be a nuisance in the area.
E) Alternative cause. Maybe the pesticide that was used prior to the newly introduced one was actually the one was responsible for the great effects.
Think of it this way: You take a pill for 6 days in order to get rid of a cough. You see no effects during the sixth days. You did not read the pamplet where it states that the medicine is cumulative. After six days, you stop taking the pill. But you now, however, have enough build up of this medicine for it to begin to work. You then go to the drug store and pick up "Grandmother's Amazing Cough Medicine." After the first dose of the stuff, your cough is gone. In this case, it could be a false attribution to claim that the second medicine is what caused your cough to go away. This so due to the fact that the first medicine finally had the opportunity to cure you.