 Moreover, if trade-offs are possible between these dimensions, we will want to know why we should sacrifice one in favor of the other. And in order to answer that question, we may need to invoke some further, underlying value. This threatens the status of self-ownership as a foundational principle in libertarian theory. Presumably, foundational principles are not based on underlying values. For many libertarians, this is not much of a concession, however. If few endorse full self-ownership, even fewer endorse it as a foundational principle.