During this topic, we will be exploring these key questions:
- Do all human beings share a common nature or purpose?
- Does it matter if we do good for bad motives?
- Is morality about reason or emotion?
Task: Write the following key terms and definitions.
- Deontological – from the Latin for ‘duty’, ethics focused on the intrinsic rightness and wrongness of actions
- Telos – the end, or purpose, of something
- Natural Law – a theory based on behaviour that accords with given laws or moral rules that exist independently of human societies and systems
- Synderesis – to follow the good and avoid the evil, the rules which all precepts follow
- Primary precepts – the most important rules to follow in life
- Secondary precepts – the laws which follow from primary precepts
- Practical reason – the tool which makes moral decisions
- Eudaimonia – living well, as an ultimate end in life which all other actions should lead towards
Introduction and the telos
Task: Watch the video below for a brief introduction to Natural Law
Natural Law is an ethical theory which was developed by St Thomas Aquinas (1225-74). His thinking is central to Catholic moral thought and his major work was Summa Theologica (1265-74). It is often believed to be a solely catholic ethical theory, however not all natural law supporters are catholic.

Natural Law thinkers believe that there is a human nature, which we should live in accordance with.
Good is to be done and evil is to be avoided. All other precepts of the natural law are based upon this.
Summa Theologica
Hugo Grotius (1583-1645) also developed the theory of natural law as rational principles that all people should follow. John Locke, Samual Clarke and William Paley have all also developed the natural law theory.
Where did natural law theory come from? The Greek Stoics believed that human beings had a divine spark which enlightens the laws needed for human happiness. The Greek philosopher Aristotle wrote:
The natural is that which everywhere is equally valid, and depends not upon being or not being received… that which is natural is unchangeable, and has the same power everywhere, just as fire burns both here and in Persia.
Nicomachaen Ethics; Book V, ch.7
Natural law predates Christianity and does not rely on Christian belief. It appeals to the belief that some things are known to be wrong intrinsically, due our ability to be rational. An example of this is incest. Humans understand incest to be wrong, and can be observed to be counter productive to human flourishing. Human flourishing is the ultimate goal of natural law. Incest leads to disabilities and illnesses and can have a negative psychological impact. Therefore, by natural law, incest is wrong.

Even in ancient societies, incest was thought to be wrong. In Ancient Egypt, the Pharaoh was permitted to marry his sister, as they were believed to be Gods and not humans. However, for the rest of society, incest was strongly forbidden. Tutankahmen was the product of incest, and was disabled and died very young.

A supporter of natural law argues that we can know by reason alone, what is right, and what is wrong. Therefore, they would argue that murder, theft, rape etc all prevent human flourishing and therefore are wrong.
When Aquinas became central to teaching within the Catholic Church, natural law became entwined with God and Christianity. Aquinas’ version of natural law is referred to as Thomas natural law, which has the sole goal of achieving true happiness for humans.
Natural moral law is that moral order which man can recognise in the nature of beings by means of his reason; independent of positive divine revelation.
C. Henry Peschke: Christian Ethics Volume I, p. 105
Aquinas built upon his master’s teaching (Albertus Magnus), and he tried to reconstruct thought away from Divine Command Theory. Aquinas believed in the importance of the light of reason and thought that morality is known through reason alone.

Divine Command Theory (DCT) is the belief that something is right because God commands it to be right. Aquinas believed that God commands what is right, not that it is right because God commands it.
Task: To understand DCT further, watch this video.
Aquinas argues that natural law is a development of Aristotle’s virtue ethics. Virtue ethics teaches that being moral is to practice being virtuous and aiming for the median between extremes. For example, it is virtuous to be brave which is the median between being cowardly and being rash. For Aquinas, being virtuous is essential in human flourishing, and that all humans should aim to be prudent (using practical reason) in determining what is the right thing to do in each situation.

For Aquinas, everything on earth is seeking to achieve its goal (telos). Some things do so blindly and others have a full consciousness.
Task: Give five examples of things which seek to achieve their goal blindly.
Aristotle argued that humans are working towards achieving eudaimonia, or human flourishing. Aquinas agreed, however he thought this was not possible in this life, but that humans should live in faithful service of God and by the light of reason, in order to flourish.

Natural law is not a set of rules, as the name ‘law’ would suggest. It does not set out to permit of forbid individual actions. In Latin, there are two words for the English word ‘law’, lex and ius. Lex is a rule, as in a statute law. However, ius is the principle of the law, which is what Aquinas is referring to. Natural law does not give a series of actions which are permitted or forbidden, which is was lex would refer to. However, ius refers to justice and the actions that are taken to achieve it.
Task: Is it true that human nature is purposive? Do we all have a clear idea of what the purpose might be?