"Surprising" Phenomenon
High-stress points make a bridge likely to fracture, but aren’t the sites of fractures themselves.
Objective
The right answer will be a hypothesis that explains why stress points don’t themselves fracture, despite stress points contributing to fractures. The explanation must also explain why stress points are especially unlikely places for fractures, given that the stimulus tells us fractures generally don’t occur on those points.
A
In many structures other than bridges, such as ship hulls and airplane bodies, fractures do not develop at high-stress points.
This backs up the stimulus, but it doesn’t explain why high-stress points don’t fracture despite making fractures more likely.
B
Fractures do not develop at high-stress points, because bridges are reinforced at those points; however, stress is transferred to other points on the bridge where it causes fractures.
This explains the mechanism behind fractures. High-stress points are reinforced against fractures, but transfer stress to weaker points where fractures occur. We now know why high-stress points contribute to fractures without themselves fracturing.
C
In many structures, the process of fracturing often causes high-stress points to develop.
High-stress points make fractures more likely. We don’t care what happens after a fracture.
D
Structures with no high-stress points can nonetheless have a high probability of fracturing.
This doesn’t matter. We’re concerned with bridges that do have high-stress points.
E
Improper bridge construction, e.g., low-quality welding or the use of inferior steel, often leads both to the development of high-stress points and to an increased probability of fracturing.
This doesn’t explain why high-stress points themselves aren’t the site of fractures, despite high-stress points making fracturing more likely. It doesn’t explain the surprise in the stimulus.
Summarize Argument: Phenomenon-Hypothesis
The representatives hypothesize that the deformity in bluefin cod was caused by the chemical waste dumped into Cod Bay. This is because those chemicals are known to cause genetic mutations.
Notable Assumptions
Based on a mere correlation, the representatives assume that the presence of chemicals caused the deformity in bluefin cod. This means the representatives don’t believe some third factor in fact caused the deformity, and that the deformity rates didn’t in fact precede the chemical waste being dumped in Cod Bay.
A
What is the incidence of deformed fins in bluefin cod that are not exposed to chemicals such as those dumped into Cod Bay?
If the incidence of deformity in bluefin cod is generally 3%, then it would seem the chemicals made no difference—a weakener. If the incidence was generally 0%, then the chemicals (or some other factor) would explain the 3% rate in Cod Boy—a strengthener.
B
What was the incidence of deformed fins in bluefin cod in Cod Bay before the chemical dumping began?
If the incidence of deformity in bluefin cod was 3% before chemical dumping, then it would seem the chemicals made no difference—a weakener. If the incidence was 0% before dumping, then the chemicals would explain the 3% rate in Cod Boy—a strengthener.
C
Has the consumption of the bluefin cod from Cod Bay that have deformed fins caused any health problems in the people who ate them?
We don’t care about how these deformities impact human health. The representatives hypothesize about what caused the deformities in the first place.
D
Are bluefin cod prone to any naturally occurring diseases that can cause fin deformities of the same kind as those displayed by the bluefin cod of Cod Bay?
If the answer is yes, then these diseases rather than the chemical may have been responsible for the deformities. If the answer is no, then chemicals remain a highly viable explanation of the deformities.
E
Are there gene-altering pollutants present in Cod Bay other than the chemical wastes that were dumped by the companies?
This points to an alternate cause. If other pollutants can cause deformities, then chemical waste might not be to blame. If other pollutants can’t cause deformities, chemical waste remains a highly viable explanation.
A
a nation that fails to invest in its infrastructure need not experience any resulting decline in its standard of living
The author’s conclusion is about a nation experiencing a rise in its standard of living as a result of investment in its infrastructure, not a decline in standard of living as a result of failing to invest in infrastructure.
B
many nations are unable to make the needed investments in infrastructure
Like (C) and (E) this may be true, but it doesn’t impact the author’s argument. Even if many nations can’t invest in infrastructure, it doesn’t affect the conclusion that such investments are necessary for a higher standard of living.
C
the rise in a nation’s standard of living that is prompted by investment in its infrastructure may take a long time to occur
Like (B) and (E) this may be true, but it doesn’t impact the argument. Even if the rise in standard of living takes a long time, it doesn’t affect the conclusion that investments in infrastructure are necessary for it to occur. The author even notes that it happens “over time.”
D
a rise in a nation’s standard of living need not be the result of major investments in its infrastructure
The author mistakenly assumes that investments in infrastructure are necessary, rather than merely sufficient, for a nation to experience a rise in its standard of living. But a nation’s standard of living could improve for other reasons, without investments in infrastructure.
E
nations often experience short-term crises that require that resources be diverted to purposes other than the maintenance and improvement of infrastructure
Like (B) and (C) this may be true, but it doesn’t impact the argument. Even if a nation can’t invest in infrastructure, it doesn’t affect the conclusion that such investments are necessary for a higher standard of living.