Must Be True. The correct answer choice is (D)
The author makes an argument about the working of military deterrence, a theory where fear of retaliation (on a military level) typically makes other countries hesitate before or stop attacking altogether. Note the conditional idea within this first sentence: fear of retaliation is often sufficient to stop an attack. Based on this idea, the author continues on to conclude ("Clearly, then, ...") that a nation wishing to maintain military deterrence would need to be believed to have a retaliatory power that would-be aggressors could not defend against. Note the pointed use of "believed" in this conclusion; the author is not claiming that a nation needs to have the actual military power, but rather that it needs to project that image or be believed to have that power.
Within the argument, an interesting relationship occurs between military deterrence and retaliatory power. As described in the first sentence, the fear of retaliation often is sufficient to deter an attack:
- Fear of retaliation Deter attack/military deterrence
The last sentence then states that if a nation wants to maintain military deterrence, it must be believed to have retaliatory power, which appears as
- Deter attack/military deterrence Fear of retaliation
This is basically a Mistaken Reversal but then the question stem does something unusual: it tells you to take the arguments in the stimulus as true. In this case, you should then back off of your critique and take both the premise and the conclusion as true. Thus, the implication is that belief is necessary and somewhat sufficient for military deterrence.
Answer choice (A): This answer states that "certain knowledge" is necessary, whereas the stimulus stated that belief was necessary. This answer choice is thus incorrect.
Answer choice (B): This answer is suspect because it focuses on a nation's "own retaliatory power," and then uses that information to make a judgment about whether that nation will attack. We have no information about this, and it also seems likely to be false given the stimulus. If an aggressor nation believes its retaliatory power is greater than the target nation‘s, why not attack?
Answer choice (C): This answer choice is about belief so it may initially appear attractive. However, it makes a judgment that is unsupported. A nation might fail to attack simply because it is not very aggressive, or has other reasons for not attacking. For example, the United States likely believes itself to to be able to withstand a retaliatory attack from Canada, but at the same time it doesn't attack Canada? Why? Because the two countries are allies of course. Thus, the problem with this answer is revealed: it assumes that every nation is an aggressor and every other nation is a potential victim; that's not how the world works.
Answer choice (D): This is the correct answer choice. You might have been wary of this answer choice, because it discusses a nation's interests while the stimulus did not seem to, but certainly a nation being attacked or not attacked falls under the idea of "national interest."
Viewed in relationship to the conclusion (which establishes requirements for deterrence), the answer addresses the necessary condition here: Deter attack/military deterrence Fear of retaliation.
Essentially, if a nation wishes to have a sufficient condition occur, then it should do everything possible to make sure the necessary condition occurs. This doesn't guarantee that the necessary will occur in this specific relationship of course (because that would be a Mistaken Reversal), but it does at least help allow for the possibility that the necessary occurs. And, when analyzed with the premise, it makes even more sense that this would be a logical path to follow base don all that was said in the stimulus.
To use an analogy, the answer choice relates to the conclusion in the following manner:
- Conclusion: To get into Harvard Law School, they must believe you have a high LSAT score.
(D): It is in the interests of a student that seeks entrance into Harvard and has an unsurpassed LSAT score to let adcomms know about the LSAT score.
A similar analysis can be made of the relationship in the premise but we used the conclusion given the certainty of the relationship.
Answer choice (E): This answer choice is unsupported because it concerns the actual retaliatory power, and then makes the power requirement "greater than that of any other nation." Since the stimulus only suggested that a belief is required there is an issue with the first part of the answer. A further problem is that the relationship in the stimulus was between the relative power of two nations (aggressor and defender), and didn't hinge on having the greatest retaliatory force in the world.