This page is part of my unofficial solutions manual to the GRE Paper Practice Book (2e), a free resource available on the ETS website. They publish the questions; I explain the answers. If you haven’t worked through the Practice Book, give Section 3 a shot before reading this!
3.25: Dolphins and Boat Paint
It’s time for another round of “Same, Worse, or Better.” The way to approach this problem type (as I explained in my solution to 3.14) is to separate the answer choices into three piles: those that weaken the argument, those that strengthen the argument, and those that have no clear effect. Here, we’re only concerned with those answers that would strengthen the argument; thus, our first goal is to identify and reject the “Weaken” and “No Effect” answers so that we can focus on the most promising answer choices.
A good preliminary step is to identify the argument and try rephrasing it in your own words. In this case, you might come up with something like:
“Compounds in boat paint are contributing to increased dolphin mortality rates. Therefore, banning the paints will cause the mortality rate to drop quickly.”
Note that this argument is a prediction about what will happen if we take a certain course of action, not an ethical judgment about what we ought to do.
Now for the answers. Our first choice, (A), actually weakens the argument, if it has any effect at all. If concentrations of these harmful compounds are dropping, but mortality rates are rising, how can we be sure that the compounds are causing the die-off, or even contributing to it? And if we’re not sure that the compounds are causing the die-off, why should we believe that banning the paints will help?
Answers (B) and (D) are carefully-crafted distractors that blur the difference between a logical argument and an appeal to our emotions. If, as (B) suggests, other sea creatures are harmed by the paints too, then that gives us an added incentive for banning them (assuming we care about sea creatures). But this new information doesn’t affect the validity of the original argument, which only concerned the compounds’ effects on dolphins. The fact that manatees or seahorses are poisoned by the paints doesn’t tell us whether we are correct in blaming them for the dolphin die-off as well, just as the fact that chocolate is poisonous to dogs doesn’t imply that it’s harmful to humans. (D), likewise, attempts to cloud the issue: we can’t use other “marine animals” as the basis for predictions about dolphins. In a way, it’s the reverse of (B): the fact that anemones and clownfish can tolerate the compounds doesn’t mean that the same is true of dolphins. (After all, many types of berries are safe for birds but toxic to humans.) Both of these answers belong in the “No Effect” pile.
Answer (C), in contrast, strengthens the argument by answering a possible objection that someone might raise: “What about all the boat paint compounds that have already been released? Won’t those keep harming the dolphins?” (C) anticipates this line of reasoning and suggests that the compounds already in the ocean (and therefore exposed to water) will pose a threat only for “a few months.” If this is true, and we stop introducing these compounds via boat paint, then the problem should quickly resolve itself. Just as raising questions about an argument weakens it (answer A), anticipating and answering questions is one way to strengthen an argument.
Finally, answer (E) fails to address the original argument that banning the boat paints will lower the mortality rate. If the compounds are getting into the water in the first place, it’s fair to assume that the “manufacturer’s directions” are being disregarded, and banning the paints remains a reasonable course of action. In other words, (E) goes into the “No Effect” pile as well, leaving us with (C) as the only answer that strengthens the argument.