Brad:
The point is not _whether_ elections produce governments by the consent of the governed - because sometimes they do and sometimes they do not- but to determine _under what conditions_ they are likely to produce "just powers" as you call them, and under what conditions they are not.
On the pain of oversimplicification, that point is one of the main differences between radicals and liberals.
The radicals believe that elections, or even the type of a political regime do not bring what we call here "social justice" - the material conditions and distribution of resources do. If these material resource base produces conditions that are unfavourable for the exercisie of "liberties and the pursuit of happiness" - neither election nor other political in the world can change that sitution into a democracy (e.g. the material conditions in E.Europe have been unfavorable for a democracy, so the formal abrogation of democratic institutions does not really matter).
The liberals, on the other hand, think that it is the other way around - political superstructure has a profound effect on the material conditions (e.g. had the E. Europe adopted western-style democracy and market economy, it would have been as good a place to live as the West).
cheers,
Wojtek