The Influence of Augustine in Aquinas in His Theory of Natural Law

The Influence of Augustine in Aquinas on His Theory of Natural Law

        Natural law is as ancient as the Greeks, but it has lost none of its power to defend human dignity and it is a solid foundation for human rights. According to Cicero’s famous definition of natural law, ’[t]rue law is right reason in agreement with nature; it is of universal application, unchanging and everlasting… It is a sin to alter this law, nor is it allowable to repeal any part of it, and it is impossible to abolish it entirely… God is the author of this law, its promulgator and its enforcing Judge.’ Beside Cicero, Saint Augustine and Thomas Aquinas are also very important concerning natural law. However, in order to understand Aquinas’s theory of natural law, first we need to understand Augustine’s concept. Aquinas was born almost 800 years after Augustine’s death. Having said that, his influence in Aquinas’s theory of natural law is unquestionable.

        Augustine was a Christian theologian. That is to say, Christian thoughts had an important role in his philosophy and concept of natural law. As a starting point, it is very important to understand what he means concerning law and Divine Intellect.  In his view, ‘[w]hat does it matter to a man, in this brief mortal life, under whose rule he lives, provided that the rules do not force him to do evil.’ Among his many significant thoughts, one of the most important to legal philosophy is his understanding of Plato’s philosophy about Ideas. In this theory, Plato says that there are two different worlds, the world we live in and the world of Ideas. These Ideas, the non-physical forms represent the most accurate reality. Augustine interpreted this theory: he says that the Ideas are contained in the Divine Intellect.

We can see the presence of this thought in his second important reflection to legal philosophy: he says that it is dangerous to identify the lex aeterna with God Himself as the Stoics made it before. However, it is an act made by God: ’the Divine Wisdom is the universal law.’ He believes that there is an inner natural order to which all things are subjected. This leads us to the distinction between the human law, which is temporal and the eternal law, which is ’the Divine Intellect and the Will of God which commands us to observe the natural order, and forbids us to disturb it.’ This definition of lex aeterna was adopted by Aquinas. Augustine defined the lex aeterna as something that surrounds everything in the world: ’there cannot be anything disorderly or lawless in the universe, whether we know this or not.’ Augustine also talks about lex naturalis, which is the conscious participation of human beings in lex aeterna. This can be also called law of reason, lex rationis, which is the imprint of lex aeterna in rational men’s heart or soul. Augustine also talks about the two moral principles of lex naturalis: to render to everyone his due, and to do nothing unto another you would not have done unto yourself. Aquinas called these later the primary principles of natural law. This is an outstandingly important establishment, because these two principles define the essential meaning of natural law. To that end, Augustine’s distinction between human law and eternal law is recovered in Aquinas’s theory of natural law, which says that there are three types of law: eternal law, the reason of the mind, the reason that establishes the universe; natural law, participation of men in eternal law, it comes from reason and it is applied to everyone; human law, ius positivum, which is created by human beings.

Augustine’s another important statement is that lex aeterna is the standard of all human laws and nothing can be lawful if it is not derived from its principles. Another key thing to remember is that according to Augustine, a good lawgiver will always respect aeternal law, and the law which does not respect it is unjust law, so people should refrain from abiding by such unjust laws. In Aquinas’s theory, there is a hierarchy between human law and natural law: human law must obey natural law, because if it is unjust, it is violating natural law. In light of this hierarchy, we have a better understanding of Aquinas’s theory of resistance, which also sources from Augustine’s above mentioned thought: if there is an unjust law, people in some cases have the right to resist, they do not have to follow it.