Logical reasoning PrepTest 119 · Section 3 · Question 20

Incorrect. This answer is too broad. The argument relies only on these two instances being ethical, not all potential manipulations.

Incorrect. The selective breeding isn't accomplished by nature—it's accomplished by humans. It may be through a natural means, but that's not the same thing.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Background - Genetic engineering has led to developments

Opposing point: It involves manipulating genes, so it's unethical

Scientist: We've been manipulating genes for a while—just look at selective breeding. Therefore, it's not unethical.

Answer Anticipation:
The Scientist's argument is designed to counter an opposing viewpoint, but he agrees with that viewpoint's premise—that genetic engineering involves manipulating genes (it's kinda in the name).

How does she rebut that argument, then? By comparing genetic engineering to selective breeding. Since they both involve manipulating animals to get certain genes, the Scientist reasons that they're sufficiently similar that the ethics are the same.

However, there are two problems there.

First, the Scientist never establishes that selective breeding is ethical. If she wants to rely on the similarities being sufficient for the same conclusion to be drawn in one case as the other, she needs to establish what that conclusion is in one of the cases. In failing to do so here, her argument is flawed. She's assuming that selective breeding is ethical, so we can look for that as an answer.

Second, as in almost all arguments that rely on a comparison, she's assuming that the similarities she brings up are the relevant ones, or at least the ones that determine whether the ethics of the two cases are the same. However, she never establishes that the points she compares genetic engineering and selective breeding on are the only relevant ethical considerations. The correct answer, then, can rule out a potential difference that would be determinative here, strengthening the similarity.

Answer Explanation:
This answer establishes that the situation the Scientist claims is analogous leads to the desired conclusion. If selective breeding is unethical, then it being a type of genetic engineering undermines the Scientist's conclusion. This answer is correct.

Key Takeaway:
When an argument relies on a comparison or analogous situation to support a conclusion, make sure that it establishes the relevant conclusion for that similar situation!

Incorrect. The debate is over the ethics of certain practices, not whether they're related to human survival. While that may play into the ethics of the practice, we can't assume that without it being established.

Incorrect. This answer draws a whole bunch of new connections in order to reach the conclusion. While it may be sufficient to support that conclusion, it's definitely not necessary.