As Christians we are called to study the works of the Lord (Psalms 111:2), but did any of the Early Church Fathers between 50-800 AD, believe in natural laws theology/law? (i.e. that knowledge or theology is based on observed facts and experiences, apart from divine intervention)
Did any of the Church Fathers believe in natural theology?
Some of the Church Fathers have written on diverse aspects and beliefs in the natural law.
Paul's Epistle to the Romans is generally considered the Scriptural authority for the Christian idea of natural law as something that was endowed in all men, contrasted with an idea of law as something revealed (for example, the law revealed to Moses by God).
"For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves: Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the meanwhile accusing or else excusing one another." The intellectual historian A. J. Carlyle has commented on this passage, "There can be little doubt that St Paul's words imply some conception analogous to the 'natural law' in Cicero, a law written in men's hearts, recognized by man's reason, a law distinct from the positive law of any State, or from what St Paul recognized as the revealed law of God. It is in this sense that St Paul's words are taken by the Fathers of the fourth and fifth centuries like St Hilary of Poitiers, St Ambrose, and St Augustine, and there seems no reason to doubt the correctness of their interpretation."
Because of its origins in the Old Testament, early Church Fathers, especially those in the West, saw natural law as part of the natural foundation of Christianity. The most notable among these was Augustine of Hippo, who equated natural law with humanity's prelapsarian state; as such, a life according to unbroken human nature was no longer possible and persons needed instead to seek healing and salvation through the divine law and grace of Jesus Christ. Augustine was also among the earliest to examine the legitimacy of the laws of man, and attempt to define the boundaries of what laws and rights occur naturally based on wisdom and conscience, instead of being arbitrarily imposed by mortals, and if people are obligated to obey laws that are unjust. - Natural law
Amongst other Church Fathers who believed in various aspects of the Natural Law are Origen, Tertullian, St. Jerome, St. Hilare of Poitiers, St. Ambrose, St. Augustine and finally St. Isidore of Seville.
In Origen's treatise against Celsus there is an interesting sentence which may be taken as characteristic of the attitude of the Christian thinkers. Celsus had urged that " Law is king of all things," and Origen, after expressing a necessary qualification of the phrase as liable to misunderstanding, agrees that that which is law in the proper sense of the word is by nature king of all things, even though there may be some who have like robbers abandoned the law and deny its validity. The Christians, he says, have come to the knowledge of this law which is by nature king of all things, for it is the same as the law of God, and they endeavour to live in accordance with it. This frank admission of the truth of the conception and the identification of the law of nature with the law of God — an identification already made, at least in terms, by Cicero — is representative of the common attitude of Christian writers towards this conception.
Even Tertullian who, if any man, represents the extreme opposition to the ideas of the Greek world, uses language which is the same as that of the philosophers. Nature, he says, is our first school: we know God first by nature . Nature As the teacher, the soul the disciple) Whatever nature taught, it was taught by God. Lactantius, with his usual somewhat captious way of dealing with ancient philosophy, when discussing Zeno's principle of living according to nature, complains at first that this is too vague: there are many varieties of nature, he says, and the phrase might mean that men are to live like beasts ; but finally he admits that, if the principle means that man, who is born to virtue, is to follow his own nature, it is a good principle. These Fathers, that is, admit that there is a law written by nature in men's hearts which is the true rule of human life and conduct.
The view of the later Fathers is the same. The writer known as " Ambrosiaster," in his commentary on St Paul’s Epistle to the Romans, gives us an interesting tripartite definition of law, and a statement of the relation of the law of nature to the law of Moses. The definition is interesting, but more significant is the conception of the relation of the Mosaic Law to the natural law, as being something intended to supplement as well as to confirm it. The same conception is expressed in a letter of St. Ambrose: The Mosaic Law was given because men had failed to obey the natural law. Again, St. Ambrose says, Law is twofold, natural and written. The natural law is written in man's heart; the written laws in tables. All men are under the law — that is, under the natural law. And again: The law of God is in the heart of the just man. Which law? Not the written but the natural law, for law is not set for the just, but for the unjust man. The natural law, says St. Jerome, speaks in our heart, telling us to do what is good and to avoid what is evil ; and, again, he says that the whole world received the natural law, and the Mosaic law was given because the natural law was neglected or destroyed.
It is interesting to notice that the Fathers frequently, as we have before said, connect their treatment of the natural law with St. Paul's phrases in Romans. St. Ambrose, for instance, says that it is the Apostle who teaches us that the natural law is in our hearts St. Augustine also refers to St. Paul's words in a passage in which he divides law into three species; and St. Hilary of Poitiers does the same in describing the general scope of the natural law. He defines this as being that a man must not injure his fellowman, must not take that which belongs to another, must keep himself from fraud and jury, must not plot against another man's marriage. It is interesting to compare this with the definitions of the natural law by St. Ambrose and by St. Augustine. It is clear that these are derived from Cicero and other ancient writers.
It is unnecessary to multiply quotations. There seems to be no division of opinion among the Fathers upon the subject. Practically they carry on the same conceptions as those of Cicero and the later philosophers, and while they bring these into connection with the suggestion of St. Paul, they cannot be said either to modify these inherited conceptions or to carry them any farther.
The treatment of the law of nature in the Fathers is not complete till we come to St. Isidore of Seville at the beginning of the seventh century. Then we find that distinction which we have considered in Ulpian, Tryphoninus, and Florentinus, and in the Institutes of Justinian, restated with great direct- ness, and defined in a method which is interesting and to some extent novel. - Natural Law Pages 102-106.