Natural Moral Law is an ethical theory established by Aristotle and further developed by St Thomas Aquinas. Natural Law essentially states humans are able to deduce what is right and wrong by looking at nature, this being the one moral code universally applicable. This theory is absolutist, unchanging and deontological. While natural law is consistent with Christian schools of thought and teachings found in scripture, it is fundamentally a theory rooted in the belief that morality comes from human reasoning and is not therefore inherently Christian.
Natural Law originates from Aristotelian and Platonic ideas that there is a law within nature that can universally be applied to man. While Plato first put forward this idea, Aristotle solidified it in ‘Nichomachean Ethics’, in which he distinguished natural justice and human justice, stating human justice fluctuates and differs depending on culture, region, nation etcetera, whereas natural justice pervades all. St. Thomas Aquinas then built on this idea, tying it to Christianity in the 13th century and establishing it as a formal ethical theory. In ‘Summa Theoliogica’ Aquinas stated that essentially, right and wrong are revealed in nature and therefore humans are naturally endowed with the inclination to do good and avoid evil, and that the morality of an action can be determined by whether it fulfils the Primary and Secondary precepts. He acknowledged also that this was a theory that need not be backed by scripture as while it was supported by the Bible, at the core of it lies human reason, not biblical teachings.
Aristotle also presented the idea of efficient and final causes. The efficient cause is the act of doing something and the final cause is the outcome. For example, an efficient cause could be the act of composing and the final cause would be a piece of music. Aquinas believed one could use reason to determine the final causes of human life, and acting accordingly to said final causes would be considered morally ‘good’. Aquinas sought out to determine what the true final causes of human existence were, and came up with five final causes that are also known as the primary precepts. These are: reproduction, to live in society, to worship God, to educate children and to protect innocent life. Any action that goes against these primary precepts is therefore deemed morally wrong. Aquinas, from this, went on to present the concept of ‘secondary precepts’, which are acts deemed morally good that are essentially extensions of the first five precepts. For example, not aborting unborn foetuses would be an extension of the primary precept ‘protect innocent life’, and would therefore be deemed morally wrong as in doing so would result in a rejection of one of the final causes of human existence. The idea of primary and secondary precepts is useful to us as from it one can determine the morality of any action by seeing if it is a secondary precept or in other words to consider whether the action is in accordance with one of the primary precepts.
Aquinas also acknowledged that while human nature is ‘good’ in essence, it is possible for humans to act out of ‘apparent good’ rather than true good, and in doing so he justified why humans occasionally do immoral things. An example of this would be an affair outside of marriage, as while it is pleasurable and could potentially fulfil the final cause of reproduction, it is fundamentally wrong. He would attribute this immorality to a lack of reason used when making the decision to act in such a way. Aquinas also stated that the motivation behind actions was just as important as the actions themselves, and merely acting in a way that fulfils the precepts is not enough by itself. This means that even if one was to act in a way that would externally be viewed as morally correct, if the persons internal motivation was not also due to a want to adhere to the precepts, then it would still be morally wrong. For example, if someone were to give to charity, but only because it made them feel better about themselves, that would be morally wrong as they were not doing good for goods sake. This example would be a good exterior act, but a bad interior act. Finally he acknowledged that good intentions do not always lead to good actions, due to the double effect. An example of an action with a double effect would be someone acting in a way deemed morally correct by natural law, but that resulted in an unintentional negative consequence, this would not be morally wrong. This is because the persons exterior and interior act was morally sound, but there was an unexpected outcome that was out of their control, and would therefore not make them morally wrong.
To summarise Aquinas, building on Aristotle’s teachings, conceived the concept of Natural Moral Law as an ethical theory set out to establish purpose in human life. He believed that all actions should be performed with the consideration of God’s will, which can be seen both in scripture and in inherent human nature. The following of the Primary and Secondary precepts would lead to an eternal life with God after death as they are derived from human nature and human reason, and as God created man this would be God’s will. Acts that adhere to the precepts are inherently good, and acts that do not are inherently bad, and one must consider the motivation behind their actions in order to truly understand the morality of them. Aquinas offers a comprehensive explanation of human purpose and morality, through his establishment of Natural Moral Law as an ethical theory