Complete Question Explanation
Assumption. The correct answer choice is (D)
Premise: Scientists in the private sector can earn 50 percent more than in a government job requiring similar skills. Additional premise: Government-employed scientists would have no problem finding private-sector jobs. Conclusion: The most-skilled government scientists will leave for the private sector, unless their sense of public duty trumps their self-interest.
This argument implicitly assumes that monetary compensation is the only factor entering self-interest. What if the government jobs are safer? What if the government jobs have better job security? What if the government jobs have more reasonable hours? Any of these factors could undermine the argument. Thus, to make the argument work, it is necessary that we dismiss all of these possibilities.
Notice the question stem: We are looking for a necessary, though perhaps not sufficient, assumption which will fill in at least one gap in this argument.
Answer choice (A): Applying the Assumption Negation test: What if government scientists are equally or more likely to receive recognition and kudos for their work? This would undermine the argument, as it suggests an additional reason why public-sector work might be more attractive. This answer choice looks like an attractive candidate. However, note that we do not completely destroy the argument by applying the Assumption Negation test. Private-sector jobs could still be better in terms of self-interest, even if they do not win on the recognition factor.
Answer choice (B): What if some government research scientists earn more than the highest-paid private-sector scientists? At first glance, this seems to undermine the argument: perhaps the government is giving a salary premium for scientists at the very top of the skills ladder, and thus such scientists will not leave. However, this story would not entirely destroy the stimulus. Perhaps there is only one government scientist who receives such a premium, and perhaps he is receiving the premium for entirely unrelated reasons (maybe he's dating the boss). The author's fundamental argument could still hold in this case. Thus, the statement in this answer choice is not absolutely necessary.
Answer choice (C): The number of scientists currently employed in government jobs vs. private sector jobs is irrelevant to the issue of the incentives for scientists to switch jobs.
Answer choice (D): This is the correct answer choice. Apply the Assumption Negation test: What if government scientists do get unusually good working conditions or fringe benefits that more than compensate for low salaries? This would destroy the argument; in this case, clearly self-interest would not push the scientists toward private-sector jobs. Thus, the statement in this answer choice must be necessary for the argument.
Answer choice (E): Applying the Assumption Negation test: What if private-sector scientists work shorter hours? This would actually support the argument, not destroy it.