Natural moral law is concerned with the moral law of how a human should behave. It’s understood by reflecting on human nature and rationally working out what leads to happiness. It has prescriptive laws recommending a particular way of behaving, what one ought to do. It’s a teleological approach meaning its based on consequences but its also deontological meaning it has rules to follow thus it becomes a hybrid system. Its universal any religion can use it to guide them. It’s easy as it provides clear and concise rules ‘ there will be one law eternal and unchangeable binding all times upon all people’.
It is often used by Roman Catholic and is often over looked by more liberal thinkers. Aristole first developed Natural Moral Law and decided that although we share qualities with animals such as desires and inclinations but unlike animals we have the ability to reason. So by following a reason as apposed to desires humanity will be able to fulfil their natural and intended purpose. Thomas Aquinas liked this idea and introduced the idea of God. If God created the world ex nihilo ‘out of nothing’ God is the author of the natural world, and the world is as he intended it to be.
This made it compatible with Christianity. The imago dei (ideal plan for humans) exists within the divine mind before creation, meaning that things are planned. So when this idea is applied to embryology people who follow natural moral law argue that it doesn’t fit with Gods plan. That and embryo once fertilized should reach its end goal, which is becoming a human and any act that prevents that, is morally wrong. Natural moral law believes that it’s natural for humans to be good.
However this idea can be seen to accept embryology as it is natural for people to be good and as embryology can be seen to bring about greater good for society. Aquinas believes naturally humanity has freedom of will and rationality so may interact with nature for the benefit of humanity. This means designer babies and things which benefit the creator not the society will be deemed a sin. A sin is seen to be a misuse of freedom. In situation ethics the key premise is do the most loving thing. It focuses on agape and doing the best for society.
This means that embryology would be allowed as it’s doing the most loving thing for society as it could potentially help millions of people. Although it may seem simple situation ethics is almost antinomian as it has few rules and people are left to use their own guidance. It can be subjective and create confusion on what one person think is right and what one person thinks is right. In conclusion I think that it’s easier to follow natural moral law as it has its five set principles and clear guidelines. However this may not always bring about the best for society.