He was influenced by Aristotle’s idea of an efficient and final cause the difference being that Aristotle’s final cause was eudemonia, happiness of humanity, whereas Aquinas believed it was to be in God. Aquinas believed that the universe was created by God and therefore everything has a design and purpose. The human purpose can be discovered through examination of the natural world and study of the bible. He believed humans were given reason and freedom by God and therefore were able to choose to follow the good which allows them to fulfil their final purpose of connecting with God. He called this Natural moral law, the understanding and following of God’s final purpose.
Natural Law is an Absolute, Objective and Deontological theory. It is absolute as it is universally valid, the same everywhere. Aquinas believed that natural law could be applied to any situation, anywhere in the world, over the whole of time as it is inside humans and will never change. It is objective as it stops the user being influenced by their personal feelings or opinions when making a decision. It is Deontological as Aquinas believed it was people’s duty to follow natural law and that it is a moral obligation or commitment.
Aquinas believed that humans can access natural law and achieve their final purpose of connecting with God due to reason. Reason is the ability to think about situations and decide what action is right or wrong. God gave reason to humans so that they could access and interpret innate natural law. Aquinas believes reason is what separates humans from the rest of the animal world.
Aquinas created 5 primary precepts these were; Preservation of life, Reproduction, Educating the young, living harmoniously, and worshiping God. He believed that humans must uphold the primary precepts in order to fulfil gods will and to achieve their final purpose, this is good. Evil is to break the primary precepts. Reason is needed in order to be able to follow the primary precepts, without reason humans would never have been able to form them let alone understand them.
Aquinas accepted that the primary precepts however would not be enough information to base all decisions on so more specific secondary precepts can be created which state what actions we should or should not do based on whether or not they uphold all the primary precepts. For example, a secondary precept could be: not use contraception, as while it upholds some precepts e.g. educate the young by teaching them to protect themselves from diseases it breaks precepts such as reproduction by preventing this from happening. Reason is also needed in order to create the secondary precepts as you need to be able to understand the primary precepts and work out whether the secondary precepts uphold or break them.
Aquinas believed there were four levels of law in existence. The highest is Divine law which humans do not have access to as it is set by god however can get a glimpse into it through Divine Law which are clues give in sacred texts and teachings of the Christian church. Natural Law which is the innate human ability to know what is right and finally Human law which is the law develop with in society such as legal systems. Reason is needed for each level of law. Firstly in order to follow human law you need to be able to justify whether a law is worth following. For example, the law to not murder will only be followed if people agree that this is wrong. Reason is need to follow natural law as while it is an innate human sense of right and wrong you need reason to be able to interpret the ideas into everyday life.
Aquinas believed that there was a link between happiness and virtuous behaviour. Reason guides people to develop the right virtues. Virtues are important as they represent the human qualities needed to live a moral life and ultimately connect with god. There are four cardinal virtues which Aquinas believed reason