Natural Law Theory

Here is a small video I created explaining Natural Law Theory (Below is transcript):

In this video I explore the strengths and weaknesses of Natural Law:

Transcript of Natural Law Theory

St Thomas Aquinas developed Natural Law theory from Aristotle and the Stoics in the 13th century. Natural Law is an absolutist and deontological theory. To believe and use Natural Law theory, one has to believe in God because Natural Law believes there is one Natural Law which has been issued by God. This means that what is wrong in one situation is wrong in ever situation and to determine what is right and wrong we look at the action itself, not the consequences. There is emphasis on innate human reason to work out how you should be living. Natural law is useful on issues where is the Bible is silent e.g. IVF.In order to use Natural Law correctly we need to identify what is known as the primary precepts. These are the basis of the theory. We need to first agree that these are the main function of life. The primary precepts are the five purposes of human life. The five primary precept are: (i) reproduction (ii) life – to live/ the supreme good (iii) education – makes people independent and fully adult (iv) worshipping God and (v) law and order – upholds justice. These precepts are immutable; they cannot be changed. From the primary precepts, secondary precept form. For example if we examine the principle of life and it is there to ensure that all actions which are life threatening are in the moral law as wrong e.g. murder, abortion, euthanasia, suicide etc are all wrong because the involve going against the precept of life.However, in reality it is not as easy as one action is good and one is evil. Some actions lead to both good and bad consequences which ever way you try and deal with it. For example, a pregnant women finds out she has cervical cancer. If the doctor performs a hysterectomy the baby dies and the mother survives. On the other hand, if she gives birth both the mother and the baby are at risk of dying. So whatever action the doctor takes there will both goos and bad consequences. This is called the principle of double effect. In these situations, two criteria need to be met to make it a permissible action. Firstly, the act itself must not be wrong and secondly, the person doing the action must not directly intend the evil outcome. So he doctor would do the hysterectomy with good intentions of saving the mother. This justifies his action.Casuistry is what applies these primary precepts to individual circumstances. These makes Natural Law quite flexible. It ensures that a solution can be produced from any situation. However, many consider this to be a weakness of the theory.They use the term casuistry pejoratively. This is because on one hand it states it is an absolutist theory and on the other it is allowing room for flexibility.

Natural Law allows us to know the divine and moral law through reason and revelation. Following Natural Law helps us perfect our virtues; both natural and theological. Natural virtues include prudence, temperance, fortitude and justice. Theological virtues include faith, hope and charity. For example, the primary precept of life means that life is extremely important. Therefore, the natural virtue of fortitude is perfected because no matter what happens, one is encouraged to stand strong and take care of our life and as mentioned before suicide will be considered immoral. 

Natural Law is based on five assumptions: (i) everything in nature has a purpose, (ii) nature was created by God, (iii) failure to develop this nature to the fullest is an imperfection, (iv) nature and its moral laws are knowable through reason and (v) natural law is part of some divine plan. Thats why for some people the theory fails. However, it has worked well and influenced the Roman Catholic denomination. For example, Roman Catholics believe abortion is wrong based on that it destroys the purpose of life: to live.

As mentioned, at the beginning Aristotleʼs philosophy influenced the Natural Law theory quite a lot. Aristotle in his theory of causality distinguishes between four causes which helps to explains something fully. Two of the four causes, efficient and final cause, Aquinas used to formulate the Natural Law theory. The efficient cause is what gets things done and the final cause is the end product. Hence, Aquinas goes on to say with us the accomplishment of the final cause/end product that equates to ʻgoodʼ we are doing the correct thing. If we can understand the final cause of an organism we can then work out the efficient cause/ the necessary processes to get the final cause done.

Natural Law is part of the branch of normative ethics. This is different to descriptive ethics. Natural Law is part of normative ethics because the impact of Aristotle’s causes moves it from being a theory that deals with what the population actually think it is right and wrong (descriptive ethics) to what they should think is right and wrong (normative ethics). This is because the natural processes required to fulfill the final cause are what should be right, not necessarily what is right at any given time. 

Natural Law: Strengths & Weaknesses

In the table below are the strengths and weaknesses of Natural Law. Please find underneath it a show video on the same topic. 



1. There is emphasis on innate human reason which is a positive because unlike emotions reason does not change. It also means the theory is universal and can attract a large number of supporters.

1. Natural Law finds it difficult to relate to complex decision to basic principles in practice e.g. should more money be spent on hospitals or schools?

2. Clear-cut approach to morality and establishes common rules.

2. It commits a Naturalistic Fallacy according to G.E.Moore. One cannot derive an ought from an is i.e. is we assume God created a moral law is a fact or that we have a natural inclination to care for others as a fact- this does not we ought to follow the moral law or care for others.

3. The basic principles of preserving human life, reproduction, learning and living in a society are common in all cultures hence Natural Law is a reasonable theory.

3. Natural Law is based on five assumptions, the primary one being that humans and the world in general has a purpose, however, modern science can be used to show why this isn’t the case.

4. Natural Law does not just dictate what should be done it goes beyond that, like Virtue Ethics, it concentrates on human character and virtues.

4. Neilsen uses cultural relativism to question Natural Law and the belief in one common law.

5. Natural Law relies on practical wisdom as well as reason including the body, some emotions and passions sometimes.

5. Baron says that relying too much on reason is bad because this leads to corruption as human nature is corrupt. He believers it is better to follow scripture and revelation. 

6. All things required for happiness e.g. health, friendship etc are morally good and can be achieved through Natural Law.

6. It is difficult to work out the primary purpose of everything e.g. is the primary purpose of sex to procreate or enhance a relationship – the clitoris provides evidence that the sole purpose of sex is not just to have children.

7. It is useful for the issues where the Bible is silent e.g. IVF

7. Some Catholic Scholars believe Natural Law is not enough on its own to be a true Catholic- Church teaching and revelation are of utmost interest too!

8. One cannot rely on predicting consequences because often we are wrong so Natural Law provides a good alternative to consequentialist theories

8. Vardy and Grosh criticize the way Aquinas works from general principles to lesser purposes and sees his view of human nature as unholistic and simplistic. 

9. It puts a high premium on life and protects the vulnerable.

9. It is self-contradictory you cannot say that clear-cut rules are provided and then uses casuistry to allow room fro flexibility.

10. It upholds human rights and has been included in the UN declaration of human rights.

10. What is more important actions or consequences? e.g. if a man with an axe asked you where your friend was surely it is more moral to lie and save the life of your friend?

11. Casuistry allow it benefit from flexibility as well as adhering to benefits from being absolutist.

Kantian Ethics: Strength & Weaknesses

I have recently updated this table so not all strengths and weaknesses are discussed in the above video.



1. Creates a distinction between duty and inclination. Inclination is may be because something benefits us but morality is something above that it is about duty.

1. No rules if two duties conflict e.g. our duty to make other happy and our duty not use an embryo for genetic research even though genetic research makes people happy. Strangely Kant would argue in this situation one duty must not be a true duty. Furthermore, it can impractical in terms of trying to fufil all duties e.g. the duty to care for all patients equally in a hospital faced with a fixed budget.

2. Makes justice impartial because you cannot promote happiness if that happiness undermines another happiness. This is also a criticism of utilitarianism.

2. Personalised rules can not exist as they cannot be universalised. (Could also be a strength)

3. Humans are given intrinsic worth, dignity and respect. Demonstrates that humans have rights.

3. No allowance for compassion or sympathy.

4. We are equal individuals unlike some forms of Christian ethics which suggests that if you do not follow the Lord Jesus Christ you are not equal to other people.

4. What is more important consequences and people or actions? e.g.. man with axe example.

5. Easy to follow with a clear criteria because it is based on innate human reason. More importantly gives us answers which arguably other theories like Situation Ethics do not.

5. Kant’s second formulation of the categorical imperative can be difficult to use in terms of world politics. For example, we cannot scarifice the few at war for the sake of many.

6. People generally do have the same idea about morality.

6. Kant’s deontological theory of ethics is in fact vague. The reason being no two moral situations are the same hence can one maxim fill both situations. No. Is murder the same as self-defence, suicide, abortion?

7. People recognise the idea of duty as a part of being human.

7. The theory only works if everyone agrees with it which is clearly not true. For Natural Law or Virtue Theory to work one doesn’t need everyone to work.

8. It is wholly secular which means it does not rely on the assumption that there is a God unlike Natural Law which if the existence of God is rejected then so is Natural Law.

8. It commits a Naturalistic Fallacy according to G.E.Moore. One cannot derive an ought from an is i.e. can ought really imply can?

9. Is it really universal can everyone really be classified a rational moral agent?

10. Kant argues that happiness is the by-product of morality not the intention behind it – is this suggestion really logical – why would you follow it then?

11. Not everyone is capable of ration decision-making hence theory is not universal.

Strengths and Weaknesses of Utilitarianism

Utilitarianism Bentham – Act Utilitarianism Mill – Rule Utilitarianism
Strengths (Bentham 2 – 5 taken from Wiki answers ) 1. Easy to use – clear criteria and offers a systematic approach to ethics.

2. Utilitarianism cannot be faulted on its morals as it clearly seeks the happiness and fairness for the largest number of people, which has always been an important consideration in the works of government and other major powers, as well as in everyone’s everyday life.

3. Designed for global politics unlike Kantian ethics.
Also, it considers the consequences of all actions, which is key in building a civilized society. If people were not aware of consequences then there would be no deterrent to commit crime.

4. Also, it encourages a democratic approach to decision making, and minorities are not allowed to dominate.

5. It does not rely on any controversial or unverifiable theological or metaphysical claims or principals, so it is accessible to everyone.

1. Mill considers emotions a form of higher pleasure which is a strength because it can make the theory a little less impartial and allow more room for emotions. In the house on fire example (Bentham Weakness 3) Mill could possibly allow you to save your mother arguing  your emotions are a higher pleasure and since he gives no explanation of what to do if pleasures clash we could justice the saving of the mother.

2. Mill’s idea of creating generalized rules makes the theory more objective and provides us a means to creating universal rules.

Weaknesses 1. Difficult to predict consequences e.g. if you plan to hit someone you might predict that they will be upset because 99.9% of the time this is the result however, what if the person turns out to enjoy it and get pleasure out of pain – all you consequences are wrong!

2.Utilitarianism is a demanding theory as something as simple as buying an ice-cream can be deemed immoral because you know that the money could be spent elsewhere in order to get the greatest good for the greatest number.

3. Some critics argue it is too impartial – if a house was on fire and you could only save your mother or the world’s best sergeant you would according to the PoU (principle of utility) have to save the sergeant. No room for emotions. John Rawls advocates this criticisms pointing out that it could support a more dictatorial society just because it produces the greatest amount of pleasure.

4.Utilitarianism is subjective – what is moral for one person isn’t the same for another implying that no such universal law system can exist.

5. Utilitarianism implies that everyone has a moral faculty (awareness that gives us a sense of moral judgement) and not everyone has this young kids, disables persons etc. This alienates people from the theory.

6.Bentham and Mill both commit a naturalistic fallacy according to G.E.Moore, just because something is desirable and produces a lot of pleasure does not imply that we ought to pursue that action.

1. Difficult to predict consequences e.g. if you plan to hit someone you might predict that they will be upset because 99.9% of the time this is the result however, what if the person turns out to enjoy it and get pleasure out of pain – all you consequences are wrong!

2. Utilitarianism is a demanding theory as something as simple as buying an ice-cream can be deemed immoral because you know that the money could be spent elsewhere in order to get the greatest good for the greatest number.

3. Utilitarianism implies that everyone has a moral faculty (awareness that gives us a sense of moral judgement) and not everyone has this young kids, disables persons etc. This alienates people from the theory.

4. Mill makes several elitist claims e.g. for example it is better to a dis-satisfied Socrates than a satisfied pig (comparing not so intelligent people to pigs), claiming that the higher your moral faculty the more difficult to find pleasure (as not so intelligent people are satisfied with almost anything). Yet what Mill fails to acknowledge is if through utilitarian values a pig can be satisfied then this devalues the intellectual ability of all humans.

5. Mill uses non-utilitarian values such as justice (supreme moral good) and from this we can infer that there are more important things than happiness and this inference destroys the foundation of utilitarianism.

6. As mentioned previously, Mill does not discuss what happens if rules/higher pleasure conflict. Adding to the ambiguous nature of utilitarianism.

7. Furthermore, given that the rules are generalized and formulated through experience this means that they are not absolute and can be broken. But it is difficult to see how one would know when an exception could be added and if we keeping using exceptions and don’t make Mill’s utilitarianism rigid then this some scholars imply collapse it back to act utilitarianism. E.g. the rule tell the truth unless a lie produces more pleasure isn’t that essentially Bentham’s form.

8. No two moral situations are exactly the same so how can rules based on past different (Albeit similar) circumstances helps us with new situations?

9. Moreover, Mill argues that a competent judge would always pick higher pleasures over lower pleasures yet this is not true for all circumstances e.g. if Mill was somehow stranded in a desert he would not pursuit poetry or imagination he would pursue drinking water – which is a lower pleasure- doesn’t this mean he has an infirmity of the mind?

10. Bentham and Mill both commit a naturalistic fallacy according to G.E.Moore, just because something is desirable and produces a lot of pleasure does not imply that we ought to pursue that action.

Deontological and Teleological Ethics

Deontology and Teleology are two specialist terms used to separate ethical theories. They difference between deontology and teleology, is in essence, the same as the difference between absolutist and relativist theories.

Deontology: This means the same as absolute. The ethical systems are based on some form of a rule system. Following a deontological system such as Kant, Natural Law or some forms of Christian ethics means that the moral thing to do is one that does not change from situation to situation. For example, according to Kantian ethics it will always be wrong to lie even if it saves someone’s life. This is because consequences are not taken into account and the universal law does not change.

Teleology: Teleological theories are the same as relativist theories. They state that the moral thing to do is one which will change from situation to situation because the consequence of an action is sovereign. Ethical systems like Utilitarianism and Situation ethics voice this belief. They suggest that lying can only be moral if it results in the most pleasure for the most people (Act Utilitarianism) or the most love towards the most people (Situation Ethics).

Below is a video outlining this and some key strengths and weaknesses:

Kantian Ethics

Kantian Ethics is summarised in the video tutorial below:



The strengths & weaknesses of the theory can be summarised as follows:

Strengths and weaknesses to Kant’s deontological theory of ethics

  1. The clear distinction between ‘emotions’ and ‘duty’ is important, it ensures that decisions are made out of something more than ‘urges of the moment’. For example, if you see someone hurt on the street, rather than acting just out of compassion, it is better to act of duty. This is gives something extra to the action taken.
  2. The theory can be applied to everyone, regardless of culture, race, religion etc.
  3. The appeal to innate human reason establishes a clear criteria for what constitutes a moral action. This makes it easier to deduce right actions to take.
  4. It respects human life without exception. Kant’s deontological of theory goes against suicide, abortion, murder etc. Even killing out of love is seen as unmoral.
  5. This respect in time demonstrates that human beings have rights e.g. they have a right to be told the truth.
  6. It is wholly secular which means it does not rely on the assumption that there is a God.
  1. It works only if everyone agrees to it especially when fulfilling the maxim of Kingdom of Ends.
  2. There can be conflicts of duty e.g. we have a duty to protect human life as well as we have duty not to lie but what if lying is the only way to save someone’s life? Kant’s reply to this criticism is interesting, he says that there is no such thing as a conflict in duty we need to identify which one of the two is not a duty.
  3. Kant’s theory falls into making a naturalistic fallacy – can ‘ought’ really imply ‘can’ and if this fails so does Kant’s ethical system.
  4. Can we really say that the action itself is really more important than the consequences?
  5. Does this theory really apply to everyone – what if someone is not capable of rational decision- making like a baby or someone with a disability.
  6. There is not a mutual consensus between everyone tat ‘my duty in one situation is my duty in every situation’
  7. Can this theory really be used in real life e.g. to be moral does everyone really need to try and fulfill their potential or give others happiness, can they not just be happy in themselves without causing others harm.
  8. Is Kant correct in saying that happiness is a by-product of leading a moral life not the intention behind it.
  9. For Kant, ‘rationality’ is extremely important, but just following the above point is it really realistic for Kant to overlook ‘fellowship’ because emotions, concerns, hopes etc are not part of his moral equation. I mean after all we are mortals.
  10. Obviously, for some theist the fact that God is excluded from the moral exclusion is a definite negative.


Evaluation of the use of analogy for ‘God-talk’


1. Defects the problems raised by equivocal and univocal language

2. Shows religious language is not absurd and can provide some understanding of God.

3. It avoids anthropomorphism.

4. Hick argues that enables to make statements yet still preseve the mysterious element to the Judaeo-Christian God.

5. Affirm the nature of the deity to the believer as well as allowing the believer to believe they are in a purposeful relationship with the deity


1. If we say John is bad is that also a refection of God’s attribute? How do we know which analogies are appropriate to God.

2. Duns Scotus argues that it is vague and leaves us unable to understand God and his actions.

3. Assumes similarity between humans and God which is difficult to accept if God is an external being which is completely different to humans.

4. In respect to the analogy of proportion, is it really possible to make comparisons between necessary and contingent beings, its like comparing apples and pears.

5. Why bother with religious language if God is mysterious? It is far too neat – is the believer just trying to have his cake and eat it.

6. Patrick Sherry points out the believers usually use religious claims literally not analogically.