Paragraph: At an enormous research cost, a leading chemical company has…
2024
Paragraph: At an enormous research cost, a leading chemical company has developed a manufacturing process for converting wood fibers into a plastic. According to the company, this new plastic can be used for, among other things, the hulls of small sailboats. But what does the company think sailboat hulls used to be made of? Surely the mania for high technology can scarcely go further than this.
Which of the following, if true, would most seriously weaken the author’s conclusion?
- A.
The wood used in producing the plastic is itself in increasingly short supply.
- B.
The plastic produced by the process is considerably lighter, stronger, and more watertight than wood.
- C.
The cost of the manufacturing process of the plastic increases the cost of producing a sailboat hull by 10 to 15 percent.
- D.
Much of the cost of the research that developed the new process will be written off for tax purposes by the chemical company.
Attempted by 3 students.
Show answer & explanation
Correct answer: B
Concept: In a critical-reasoning “weaken” question, the author's conclusion rests on an unstated assumption. Here the author concludes that switching from wood to a manufactured plastic for sailboat hulls is needless “high-tech mania,” which assumes the new material gives no real reason to be preferred over wood — it's simply change for its own sake. To weaken this conclusion, an answer must attack exactly that assumption by supplying a genuine, boat-relevant reason the new material is NOT a pointless substitute.
Application: Read each option against that assumption. A fact that reports a concrete, hull-relevant edge of the plastic over wood directly knocks out the “no real reason, so it's just mania” assumption: it gives the company an actual justification for the switch, which is precisely what the author's dismissive conclusion denies exists.
Cross-check by contrast — run the same test on the other three options:
This tells us something about the SUPPLY of the raw wood used to make the plastic — a fact about the manufacturing process's inputs. It doesn't engage with the author's argument at all: whether the wood supply is tight has no bearing on whether switching to plastic hulls was a sound decision, so it leaves the conclusion completely unweakened (if anything, it feeds the author's suspicion of the whole venture rather than countering it).
This tells us the new process makes hulls costlier — a fact that argues FOR the author's position, not against it. A pricier alternative supports the claim that adopting it was excessive, so citing extra cost only reinforces the conclusion rather than weakening it.
This is a detail about the company's tax accounting for its research spend — a fact about the firm's finances that has nothing to do with the sailboat hulls themselves or whether making them from the new material was justified. It simply doesn't engage with the argument.
Result: Only the option that reports a genuine, boat-relevant reason to prefer the plastic removes the ground the author's conclusion stands on, so that is the one that most seriously weakens it.