In general, political philosophy is concerned with the distinction between the ruler and the ruled. That is, who ought to be in charge and why? How much power do various rulers have and why?
The interesting question for political philosophy, though, is whether it should be practical or theoretical. Should philosophers concern themselves with what is possible in human politics or with what is the best inhuman politics?
The divide is largely historical. Aristotle, and most philosophers of the tradition, did politics by contemplating the best human society and describing existing human societies in comparison to the best. He was not interested in directing human affairs, but in discovering the nature of human affairs.
Machiavelli (1469-1527) came along and said, no, political philosophy is a matter of finding the most effective way to get the job done. The idea of the best is impractical, because it cannot be realized in the "earthly city," as Augustine would call it. Looking at human nature is not a major concern, either, because whatever that nature is, it is clearly corrupted.
Which side you fall on depends on your answers to a few questions. Is there a human nature that has a determined best? Is there a knowable best human political associations? In other words, is there an end in human politics that humans do not create for themselves?
Without an end, or a best, political philosophy cannot be contemplative (or theoretical). There would be no ideal against which to judge the actual communities and governments we live in. Without an end that is built into human nature, politics becomes a matter of getting power in order to enforce your own, self-determined purposes. (See "ends and purposes," June 2007)
That's the drama of politics.