Libertarianism is a political philosophy whose defenders have set its foundations in the principle of self-ownership. But self-ownership supplies an uncertain basis for such a theory as it is prone to a number of serious difficulties, some of which have been addressed by libertarians but none of which can ultimately be overcome. For libertarianism to be a plausible way of looking at the world, it must look elsewhere for its basic principles. In particular, it needs to rethink the way it understands property and its foundations.