Natural Law is a deontological theory of ethics. According to Thomas Aquinas it is absolutist and depends on the idea that God created everything with a purpose and supreme good is found when that purpose is fulfilled. For Aristotle, who heavily influenced Aquinas’ ideas, he believed that supreme good for humans is happiness. Thomas Aquinas agreed with Aristotle, but saw a human’s supreme purpose to be perfection.
The fundamental principles of Natural Law are the primary precepts. The 5 primary precepts are: The preservation of life, Reproduction, The nurture and education of the young, living peacefully in society, To worship God. These primary precepts are always true in that they point people in the right direction and are necessary for human flourishing. The precepts according to Aquinas were seen to be a ‘reflection’ of Gods Eternal Law. The secondary precepts, which are worked out from the primary precepts are dependent on our own judgement. this makes the secondary precepts more theological than deontological. The secondary precepts cannot be read like the primary. For example, the primary precept of reproduction may need secondary precepts that explain what is acceptable sex and what is an acceptable way to have children e.g. IVF. The primary precepts allows for humans to have a clear-cut approach to morality and it also establishes common rules, making it easier for people to make the right decision. Also as the basic principles of preserving human life, reproduction, learning and living in society peacefully are common to most culture’s it make the Natural Law theory more reasonable.
All the things that we require for happiness are morally good. Things such as our health, our friends and so on. They are good because they make us happy and with happiness come the fulfilment of our natures which is a human’s purpose in life. There are many strengths of Natural Law and they can be applied in nearly all situations and it provides a clear-cut approach to morality and establishes common rules.