Marine Biologist: To restore the declining coral reefs off the coast of Marland Island, the local government banned commercial fishing within a 10-mile radius three years ago. Recent surveys show that the coral density in this protected zone has increased by 30%. Therefore, the ban on commercial fishing directly caused this recovery of the coral reefs.
Which of the following are necessary assumptions upon which the marine biologist's argument depends? Select all that apply.
- The observed increase in coral density was not entirely the result of environmental changes independent of the fishing ban.Answer
- Prior to the ban, commercial fishing operations were negatively impacting the health of the coral reefs in the protected zone.Answer
- CMarland Island's coral reefs will eventually return to their historical maximum density if the commercial fishing ban is strictly maintained.
- DNeighboring marine areas that did not implement similar commercial fishing bans experienced continued declines in their coral reef densities over the same period.
- EThere are no marine environments anywhere in the world where active commercial fishing and healthy coral reefs coexist.
Answer
The correct assumptions are that independent environmental changes were not the sole cause of the recovery, and that commercial fishing was actually negatively impacting the reefs before the ban.
When an argument concludes that one event directly caused another simply because it occurred beforehand, it relies on two primary types of necessary assumptions. First, it must assume that there was no alternate cause entirely responsible for the observed effect (a 'defender' assumption). Second, it must assume that the supposed cause actually had a mechanism to influence the situation. The correct choices establish that natural environmental changes did not act alone, and that commercial fishing was genuinely harming the reef prior to the ban.
Step-by-Step Solution
Key Concept
Necessary Assumption (Defending Causal Claims)