What is the legitimate purpose of government? From my radical libertarian perspective, the only legitimate purpose of any government is to protect the rights of the individual from being violated. This is what The Declaration of Independence was talking about. If the government fails in this it has to go. If the government becomes the main culprit violating individual rights it has negated the very reason it had for existing in the first place. Therefore in order to fulfil its duty to protect the rights of the individual it is necessary for that government to abolish itself.
Every government sooner or later, usually sooner, becomes the people's worst enemy.
