Natural law and natural rights follow from the nature of man and the world. We have the right to defend ourselves and our property, because of the kind of animals that we are. True law derives from this right, not from the arbitrary power of the omnipotent state.
Natural law has objective, external existence. It follows from the ESS (evolutionary stable strategy) for the use of force that is natural for humans and similar animals. The ability to make moral judgments, the capacity to know good and evil, has immediate evolutionary benefits: just as the capacity to perceive three dimensionally tells me when I am standing on the edge of a cliff, so the capacity to know good and evil tells me if my companions are liable to cut my throat. It evolved in the same way, for the same straightforward and uncomplicated reasons, as our ability to throw rocks accurately.