Natural law is a fusion of the secular philosophy of Aristotle (who claimed that everything had a purpose and therefore the fulfilment of these purposes was good, e.g. a good knife cuts well) and the religious tradition of the church by Aquinas. Natural law was to be a supplement of the laws given in the scriptures and draws much inspiration from the bible. Paul in Romans 1-3 argues that the moral law of God is evident from the nature of humans and the world, “Ever since the creation of the world, his invisible nature, has been clearly perceived in the things that have been made.” (Romans 1:20) In Matthew 19:3-9, Jesus observes that natural law should make it clear that divorce is wrong, “For your hardness of heart Moses allowed you to divorce your wife, but from the beginning it was not so.” Marriage was designed for the building up of the married couple by each other and for birth and secure upbringing of children; divorce goes against God’s aim.
Peter Mullen, Working with Morality, states, “Reason and the regularities of the natural world should be your guide.” Though are ability to reason we can get a sense of right and wrong. We can think freely for ourselves and discover God’s intention and follow natural law. In other words we must use our reasoning powers in order to work out what is moral. This helps us deal with ethical issues which are not dealt with in the scripture e.g. euthanasia.
In his book, Summa Theologiae, Aquinas maintained that we have four cardinal virtues (‘cardo’ meaning ‘a hinge’) on which are morality hinges and these four things inform as reason as well as the Decalogue. It has also maintained that we have seven capital vices. The cardinal virtues are prudence, justice, fortitude and self control. Pursing what is morally right will help us to develop these virtues and vice versa. The seven sins of morality are just the vices of pride, avarice, lust, envy, gluttony, anger and sloth. Aquinas maintains that these, in contrast with the four virtues are totally opposed to achieving the goals set out for humans in natural law. These natural virtues are expanded by the revealed virtues of faith, hope and charity derived from St Paul in Corinthians and “Aquinas held that the greater the extent to which these are developed by the individual, the greater the obedience will be to natural law.”(Vardy and Grosch)
When people sin according to Aquinas, it is because they are pursuing what they think is good. Human nature is generally good and therefore if we do wrong it is because we are in pursuit of an apparent good, e.g. abortion, can seem like at a good thing at times. According to Vardy and Grosch, “Humans seek apparent good, but this is not true good; only apparent good because it does not conform to the perfection of human nature which all humans share.” A historical example would be that of Hitler and Stalin, who did not seek out evil but sought what they thought, was right. The theory of natural law states that you are only responsible for the immediate consequences of your actions – not for the secondary or unintended effects of your action. This adds flexibility to the theory of natural law in such areas as just war and etopic pregnancy. According to Thompson, “Natural law is based on nature as seen by human reason enlightened by Christian faith. In the light of Jesus’ teaching and belief in God, reason can decide, by looking at nature, what is right.”
Natural law however has some faults. It depends on the belief that the world was designed by a creator. Aquinas assumes that all men must seek to worship God, atheists not taken into consideration. According to Thompson, “...if someone does not believe in God, then the natural law theory loses its foundation.” The theory also suggests that reproduction is one of God’s natural purposes of creating humankind, not considering those who are biologically incapable of having children. Thirdly, naturalistic fallacy, there is a problem with the assumption that just because something is a matter of fact in nature does not mean it ought to be obeyed by everyone. Hume argued that what is the case and what ought to be the case are different ideas. According to Jenkins, “sex does produce babies by this does not necessarily mean that people ought to have sex only for this purpose.” In some situations it may be necessary to against natural law to achieve a better end result, natural law is too flexible. According to Peter Mullen, “it may be necessary, for example to torture an innocent person to save the lives of thousands.” Finally, how do we define what is natural and what isn’t, there are some basic ideals but these are too vague to apply to specific situations. For example should we try to prolong the life of someone who is ill, for death is the ‘natural’ result? Natural law also puts too much emphasis on human reason. Human reason can be corrupted by sin, e.g. holocaust.
However there are strengths of the natural law theory. First of all, it is a universal guide. It provides humanity with a set of common moral principles and can be sued if you are religious or not (Aristotle). Secondly it is a simple, straightforward set of rules – we look at the evidence of the natural world and apply our reason to consider if something is right or wrong. And thirdly, the principles of natural law can be applied to solve specific moral problems – casuistry.
In conclusion, “The natural law is written and engraved in the soul of each and every man; because it is human reason ordaining him to do good and forbidding him to do sin.” (Pope Leo XIII)
