Natural rights begin with the idea that a human being is a form of property. The question becomes “who is the owner?” There are three possible alternatives: each person is a self-owner; someone else owns him (slavery); or he is an unclaimed good.
Natural law and common law treat the individual as a self-owner, who also has a strong presumed right to whatever he peacefully produces or acquires through his own labor, such as crops or a chair.
This conclusion may be derived from God, human nature, or logic, but it leads to the same legal place: it is inherently wrong to violate the person or property of a peaceful human being.
Otherwise stated: I do not need to contract with you in order to rightfully prevent or punish your assaulting me, raping me, stealing my purse, or burning down my home. Violent transgressions against my person and property are a priori wrong and should be treated as crimes.