You should read Machiavelli. It's instructive. Here is an exerpt that deals with this from the pragmatic prince perspective but makes it clear that it is wrong.

And it must be understood that a ruler, and especially a new ruler, cannot always act in ways that are considered good because, in order to maintain his power, he is often forced to act treacherously, ruthlessly or inhumanely, and disregard the precepts of religion. Hence, he must be prepared to vary his conduct as the winds of fortune and changing circumstances constrain him and, as I said before, not deviate from right conduct if possible, but be capable of entering upon the path of wrongdoing when this becomes necessary. (Machiavelli, 1988: 62)