Governments do not derive their authority from the consent of the governed. The US government isn't legitimate because we signed some invisible contract... It's legitimate because of human nature. My primary intent here is to show that consent is unnecessary for legitimacy.
First in this order is to clarify what is meant by “necessity”. There are two sorts, hypothetical and absolute. Hypothetical necessity is what is meant when we say, “a heartbeat is necessary for an animal to be healthy,” whereas absolute necessity is what is meant when we say, “Triangles necessarily have internal angles equal to two rights.” In absolute necessity, the principle necessarily produces the effect; in hypothetical necessity, the principle is necessary for the effect but does not always produce it.
That the consent of the governed is absolutely necessary for the legitimate authority of government can easily be dismissed, for then a government could legitimately promulgate an unjust law. Injustice is never legitimate.
Nor can a legitimacy of a government require the consent of the individuals through hypothetical necessity. Were this true, any individual could waltz into a nation whose government he thought to be unjust and break laws at will without the government being able to legitimately stop him! One might retort that the majority has given consent and that this is sufficient, but this would be to posit that Democracy (which is a government type) has legitimate authority ipso facto.
It follows then that if any government has legitimate authority, it is not through the consent of the governed.
And yes, governments can have legitimate authority. Human nature proves this, for we are naturally social animals, but every society must be organized, and a government is a necessary principle of the organization of a society.
noun | au·thor | \ ˈȯ-thər \