Explaining Libertarianism: four theses: 1. Interpersonal liberty requires an explicit, pre-propertarian, purely factual, theory. 2. Liberty is and need only be morally desirable in systematic practice, not in every logically possible case. In practice, there is no clash between the two main moral contenders: rights and consequences. 3. Nothing can ever justify, support or ground any theory of liberty or its applications because it is logically impossible to transcend assumptions. Theories can only be explained, criticised and defended within conjectural frameworks. 4. The state is inherently authoritarian and also negative-sum. It reduces welfare overall, with the losses compounding over time. Libertarian anarchic order is the positive-sum solution to illiberal political chaos. J C Lester is a philosopher of libertarianism. He has written widely on the subject in books, articles and dialogues. His solution to the crucial philosophical problem of interpersonal liberty provides an explicit theory of liberty and explains how its application entails self-ownership and external property, and relates to all other interpersonal matters.