What bestows legitimacy upon a government? Views differ. I take John Locke’s view as the conventional one. Chapter VIII of the Second Treatise of Civil Government, sections 95-122, treat this question. Locke argues that citizens tacitly consent to governments in a social contract. In my opinion, neither tacit consent nor social contract are defensible grounds for declaring a government to be legitimate.
Contracts should have explicit terms and signatories. For what reasons are governments to be thought of as established by a tacit rather than an explicit consent of those governed? For what reasons are governments to be thought of as arising from a non-explicit social contract, whatever that is? There are no justifiable reasons that I can think of. Locke endorses consent of the governed, but then he completely buries it under the ideas of implicit tacit consent to an implicit social contract.
If someone should say, as they have said in criticism of libertarian thinking, that “representative government is a legitimate authority”, my response is simple. If that government is legitimate, then let that government have a referendum on its existence. Let people who are claimed to be tacitly consenting have the opportunity to dissociate themselves from or associate themselves with this government. What possible objection could there be to such a procedure if government really is supposed to be via consent of the governed? But since governments do not do this and use force to suppress breakaway movements and secessions, and since they use force to gather their taxes and impose their laws that extend far beyond the suppression of criminal activities and violations of property rights, often themselves violating property rights, I can only conclude that they are afraid that many of their citizens would reject their legitimacy if asked. So that by their own deeds and failures to obtain consent, so-called representative governments provide strong evidence that they are not the legitimate authorities they claim to be.
From a citizen’s point of view, if he is forced to pay taxes and obey unjust laws of a government he rejects, such a government is no different than a criminal enterprise that extorts money from those under its control. For such a citizen who does not consent to that government, taxes are robbery. Hence, if some critic of libertarian thought says, as they have, “The fact that taxation is a legitimate function of representative government is indisputable,” I would argue that taxation cannot be a legitimate function of a representative government if that government is not legitimate, and for those of its citizens that do not consent to that government, it is indeed not legitimate. If governments wanted to represent people legitimately, they could seek subscribers who would pay fees in lieu of taxes. That they do not do this but instead throw people in jail or steal their property if they fail to pay taxes shows again that governments are not the legitimate authorities they claim to be.
Taxation with or without representation is robbery to the non-consenting persons because they do not agree to the representation that is being claimed as a proxy for their consent. If someone tells me that I am being represented because a group of other persons have voted in someone who then declares a law imposing a tax on me, my response is that this procedure has no different result than if they all donned sheets and masks, appeared at my doorstep on horseback, and threatened to burn my house down unless I paid them tribute. Unless I have agreed to be associated with the system of voting and its outcome, it is to me tantamount to naked force. Telling me I have been represented, tacitly consented and entered a social contract is some kind of psychotic fancy.