A final strength is that to follow this key principle, both exterior and interior acts have to be good. A good exterior act is when you act in a good way for the wrong reasons, an example of this is giving money to charity, (good exterior act), to impress someone (bad interior act).
When both exterior and interior acts are used for a good nature, it shows that this key principle too the theory is very important for it to be a successful theory. If everyone obeyed this rule it would make it very easy to follow as everyone would have the right intentions. Aquinas also believed that everyone had either intrinsically good or bad actions because it humans act with their ultimate power, god is glorified. This also links with Kant’s theory on Deontology. He believed that justice was an absolute; this meant that only intrinsically good or bad. Kant said that only good will is a good so if someone acts out of good will, their exterior and interior acts will be good.
On the other hand, people argue that Natural Law fails to be a practical ethical theory.
A major weakness to this theory is the primary precept of worship God. The main weakness to this is not everyone believes in God so how can they worship God if they don’t believe in him. It is not a practical theory if some people can obey God as it is their religions and others cannot put the theory into practise as they don’t believe in a religion. Another point is that people worship different Gods so they may ask which the right God to worship is and why must it be this God instead of another. Hans Kung is a respected Catholic scholar and he says
‘Jesus talks a lot about natural things such as birds he never mentions a natural law and never justifies his teachings by referring to a natural law’
This is a weakness within the theory as to worship God you must read the Bible and as you can see Jesus does not follow any of the acts of Natural Law so how can you put it into practise if he is your moral guidance.
However if everyone did worship God it would make the Natural Law practical because everyone can achieve this principle with no issues raised.
Another weakness to this theory is that is takes away individuality by assuming all humans are similar. This shows the theory is not very practical and lazy by assuming that everyone is the same when full well everyone knows people have different qualities and opinions from one and another. By taking away individuality a lot of people question the theory asking why they cannot do this and that, picking out faults to the theory. Hughes says
‘What neither Aristotle nor Aquinas believes is that from general moral principles we can deduce what we ought to do in individual cases’
This means by using our own moral principles we have been given by living in society, we can act on most situations by ourselves with positive outcomes and without considering an ethical theory. This shows that our own individual knowledge of the situation is not taken into account making the theory unpractical and frustrating for many people.
Although if all humans were similar these guidelines would be easy to apply as everyone would go on the same principles.
Finally another weakness is that the secondary principles are there to give direct guidance upon how to live your life but these principles are hard to apply to everyday life. As the secondary precepts are generally about taking care of your own life and others around you it is hard to apply this in everyday life as most people do not come across murder or suicide on a daily basis, this therefore makes the theory hard and unpractical for everyday use. These secondary precepts are generally taught to everyone throughout society so most people would not have to be taught these.
However these secondary precepts are very important because even with the Natural Law theory these precepts fit into most societies and are very important. People could argue that they are easy guidelines to live your life by and by not doing these acts you are using them in your everyday life as you are not going against them.
Overall I feel the theory of Natural Law is an unpractical theory, this is because it is hard for someone to apply this theory in their everyday life as it has many weakness compared to the strengths. I feel the primary and secondary precepts are a very good basis to live your life but I feel even if you do not have the knowledge of this theory you would be able to put it into practise by living in society as they follow the basis of society. Thomas Aquinas had every good intention when making this theory but as you cannot use your own personal views on situations I feel it is too legalistic and with modern society today everyone feels they have the right in a say, so by following this theory it will not give them that opportunity to have their say and many people will be off put by this.