Natural Moral Law



Not by Christianity - laws deduced by human reason.

Based on idea that there is an objectively ideal way to be human and we measure our humanity against this- this rational human nature is given by God and without God, reason can still discover laws.

Came from Ancient Greek world - 4th century ARISTOTLE wrote that natural justice is independant and so should be applied to all laws despite the laws themselves varying from from place to place.He believed that everything has a purpose and 'supreme good' (eudaimonia) is when this purpose is fulfilled. He uses human ability to reason as a justification for natural law.

AQUINAS then developed Aristotle's ideas : (DIFFERENT TO ARISTOTLE'S) took view of end goal being happiness and joined it to Christian view of that goal being union with God in the next life (not eudaimonia).

Aristotle = purpose is to flourish.

Aquinas = purpose is to flourish to God.

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deontological - focus on intent/nature of action and not it's consequence BUT not fully when the goodness of act is considered alone.


knows from start what is 'good' = humans achieving their purpose.


found in human nature and not an externally imposed law.

reasoned by humanity.

written in Aquinas' 'Summa Theologica'.

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Aquinas believes that God has installed in all humans, certain inclinations to behave in order to lead life of highest good. Most important inclination is acting to avoid evil as humans were designed for perfection so wouldnt pursue evil. The reason not everyone does act 'perfectly' is because humans seek the 'apparent good' which appears good but isn't.

Aquinas believes that NML will lead us to 'supreme good'.

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4 key laws

ETERNAL LAW - God is creator = nature reflects the moral order being existent before creation as a 'blueprint' of God's mind which enables us to live a life of absolutes based on God's order.

DIVINE LAW - principles of order are revealed through divine law 1)Bible 2)Church teachings.

NATURAL LAW - discovered through human reason and not just through revelation as human nature knows evils are wrong already; source of fulfilling purpose.

HUMAN LAW - the legal system understood through discovering NML.


  • scriptures are interpreted differently.
  • governed laws may be created corruptly.
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Primary Precepts

NML has a main guiding principle : "good is to done and pursued and evil is to be avoided." Tnis leads us to primary precepts.

Aquinas believes these basic goods will lead us to 'supreme good':

  • life
  • reproduction
  • education
  • seek God
  • live in society
  • avoid offense
  • shun ignorance

He used these to compose the 3 Primary Precepts:

  • what human reason has in common with other beings.
  • what humans have is common with other animals.
  • what humans have uniquely as rational beings.

...which were later adopted by 'manualist' of Roman Catholocism and set into stone as 5 primary precepts :

  • Preservation of Life
  • Reproduction
  • Education of Children
  • Worshiping God
  • Ordered society

These are obvious by human reasoning as they're necessary to achieve 'human flourishing'. This 'telos' of happiness is found in the next life (as it can't exist in something created), when we become the loving vision of God. This idea is called the 'beatific vision of God'.



  • when we think we're following them we might be interpreting them or actions wrongly.
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Secondary Precepts

= rules that govern how we should act in specific situations.

Derived from Primary Precepts.

Aquinas uses 2 of Aristotle's causes from his doctrine 1) efficient cause - what gets things done and 2) final cause - purpose to which the thing is pointed to.

Often appear cultural relative but aren't.

Allow some flexibility - a lot stricter in Catholocism where they're classed as rules, not principles.He often waits until close to circumstance in order for moral variation to occur. This prevents mistakes from being made.

Mistakes can also be prevented in using real goods instead of apparent goods, having a good intention (interior act) behind the exterior act and following  both 4/7 of Arstotle's cardinal virtues as well as 3 theological virtues given by God's grace in St Paul's writing.

CHANGEABLE as we get closer to circumstance.

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  • an anchor of absolute moral code available universally, important amongst the 21st century rejection of traditions.
  • can evolve towards common understanding due to intrinsic human morality e.g. slavery abolishment.
  • realistic - recognises apparent goods.
  • can develop natural rights from it.
  • focuses on prcatical use of cardinal and theological values in order to develop good moral character.
  • adaptable e.g. other interpretatiom by Finnis 'Natural Laws and Natural Rights' with suggests 7 basic goods which don't presuppose God's existence.


  • Aristotle
  • Aquinas 
  • Finnis
  • John Waters - 'Socratic Ideas'
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  • Teleological view that we all share a common human nature designed by God is criticized as some people are homosexual but which is not a choice.
  • Not suitable for modern world due to the fact it makes contraception, hoosexuality and contraception immoral.
  • Not atheistic.
  • There are other theories that could be better.
  • Can lead to immoral outcomes e.g. Christians help AID sufferers but spread it through prohibiting contraceptives.
  • Some Catholics dont even agree due to the appeal of proportionalism against absolutism.
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