Do you believe that governments derive their just powers from something other than the consent of the governed?

1) "Just" is in the eye of the beholder.
2) Their powers are only "just" if they are "just" in your opinion.
3) The power of government does not require consent of the governed; see history for details. What it does require, historically, is monopoly of force. I'll be happy to point you to the requisite political science texts dealing with the subject.