Libertarianism holds that we all have a right to lead our lives as we see fit, so long as we respect others’ like right. This right implies a wide range of rights: the right to speak or write freely, without fear of governmental sanction or censorship, and the right to acquire or sell property. The only actions that can violate our rights are actions that initiate or threaten physical force against us, or that defraud us. Hence the centrality of the non-aggression principle in libertarianism. The three main arguments examined here are as follows. (i) A eudaimonistic virtue ethics, which takes the agent’s own flourishing (eudaimonia) as the final end or telos, is the best foundation for libertarianism, as eudaimonia requires self-direction, and self-direction requires strong liberty rights. (ii) The best foundation for libertarianism is the nature of justice. A just person can neither do nor accept the kinds of actions that state agents do, such as raiding our homes for drugs, because these violate our equal moral authority over ourselves, and make it harder for us to be virtuous. (iii) The unity of the virtues supports a conception of justice that takes benevolence into account, and conversely. Our rights are thus neither as stringent as deontology holds, nor as lax as consequentialism requires. A successful libertarian society also needs to care about social justice and justice in the sense of treating people as they deserve, because the unity of the virtues implies that without support and insight from justice in this wide sense, and from the other virtues, we are often likely to act unjustly even in the narrow sense of respecting people’s rights.