No, according to research by Max Bazerman, author of the best book on decision making I've ever read: Judgment in Managerial Decision Making.
Contrary to F. Scott Fitzgerald's famous quote, “the test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function,” evidence suggests that even the most intelligent find it difficult to sustain opposing beliefs without the two influencing each other.
One reason is a bias from incentives. Another is bounded awareness. The auditor who desperately wants to retain a client’s business may have trouble adopting the perspective of a dispassionate referee when it comes time to prepare a formal evaluation of the client’s accounting practices.
In many situations, professionals are called upon to play dual roles that require different perspectives. For example, attorneys embroiled in pretrial negotiations may exaggerate their chances of winning in court to extract concessions from the other side. But when it comes time to advise the client on whether to accept a settlement offer, the client needs objective advice.
Professors, likewise, have to evaluate the performance of graduate students and provide them with both encouragement and criticism. But public criticism is less helpful when faculty serve as their students’ advocates in the job market. And, although auditors have a legal responsibility to judge the accuracy of their clients’ financial accounting, the way to win a client’s business is not by stressing one’s legal obligation to independence, but by emphasizing the helpfulness and accommodation one can provide.
Are these dual roles psychologically feasible?; that is, can one person successfully play different roles that require different, and often competing, perspectives? No.
This paper explores the psychology of conflict of interest by investigating how conflicting interests affect both public statements and private judgments. The results suggest that judgments are easily influenced by affiliation with interested partisans, and that this influence extends to judgments made with clear incentives for objectivity. The consistency we observe between public and private judgments indicates that participants believed their biased assessments. Our results suggest that the psychology of conflict of interest is at odds with the way economists and policy makers routinely think about the problem. We conclude by exploring implications of this finding for professional conduct and public policy.