Aristotle is often said to be the father of natural law. Like his philosophical forefathers, Socrates and Plato, Aristotle posited the existence of natural justice or natural right (dikaion physikon, δικαιον φυσικον, Latin ius naturale). His association with natural law is due largely to the interpretation given to him by Thomas Aquinas. This was based on Aquinas' conflation of natural law and natural right, the latter of which Aristotle posits in Book V of the Nicomachean Ethics (= Book IV of the Eudemian Ethics). Aquinas' influence was such as to affect a number of early translations of these passages, though more recent translations render them more literally.
Aristotle notes that natural justice is a species of political justice, viz. the scheme of distributive and corrective justice that would be established under the best political community; were this to take the form of law, this could be called a natural law, though Aristotle does not discuss this and suggests in the Politics that the best regime may not rule by law at all.
The best evidence of Aristotle's having thought there was a natural law comes from the Rhetoric, where Aristotle notes that, aside from the "particular" laws that each people has set up for itself, there is a "common" law that is according to nature. The context of this remark, however, suggests only that Aristotle advised that it could be rhetorically advantageous to appeal to such a law, especially when the "particular" law of ones' own city was averse to the case being made, not that there actually was such a law;Aristotle, moreover, considered two of the three candidates for a universally valid, natural law provided in this passage to be wrong. Aristotle's theoretical paternity of the natural law tradition is consequently disputed.
