Thomas Aquinas
On Natural Law
Ethics and Contemporary Issues
Professor Douglas Olena
Page 102 to 104
Question 94
The precepts of natural law are like demonstrations of mathematics and logic. 
They are something like axioms.
Article 2: Many Axioms
The precepts of natural law are like demonstrations of mathematics and logic. 
They are something like axioms.
Article 2: Many Axioms
Precepts of natural law::Practical Reason
First principles of demonstration::speculative reason
Article 2: Many Axioms
102 ’ÄúThe first principle of practical reason is the one based on the concept of the good: Good is what everything desires.’Äù
’ÄúThis... is the first principle of law: Good is to be done and evil avoided.’Äù
This is the foundation for all practical reason.
Article 2: Many Axioms
The ordering of the precepts of natural law stems from the order of natural inclinations. 
toward natural good: self-preservation
toward natural animal instincts: mating of male and female, education of children, etc.
toward good based on reason: singular to man.
Article 3: Acts of Virtue
103 To act according to reason is to act virtuously.
’ÄúIn this respect, all virtuous acts pertain to natural law.’Äù
But to act virtuously is not necessarily a matter of natural law.
The exercise of reason tells us what it is to live well.
Article 4: Universality
103 Speculative reason gives us necessary or universal principles.
Practical reason deals with contingencies in human activity. 
The closer we get to particulars, the farther away we are from universality.
Article 4: Universality
103 ’ÄúWe claim that first principles of natural law are the same for all...’Äù theoretically.
But on a case by case basis in the real world, there are obstacles to applying the rule that need to be compensated for.
Question 95
The precepts of natural law are like demonstrations of mathematics and logic. 
They are something like axioms.
Article 2: Whence come
104 ’ÄúWhether every law fashioned by humans is derived from Natural Law’Äù
Some laws are produced by deduction from principles.
Some laws are produced when common forms are tailored to specific cases.
Article 2: Whence come
104 ’ÄúThe prohibition of murder is derived from the general principle that evil should not be done.’Äù
But carrying out the sentence against the murderer is a determination not directly derived from natural law but from society.
Article 2: Whence come
When we deduce punishment from principles of natural law they have the force of natural law.
When we determine the punishment from some other source, it does not have the force of natural law.
Article 3: The meaning
104 ’ÄúThe end of human law is the well-being of humans’Ķ accordingly,’Ķ the first condition of law posits three things:
That it accords with religion: inasmuch as it is proportioned to divine law
That it fosters discipline: inasmuch as it is proportioned to natural law
That it advances well-being: inasmuch as it is proportioned to human needs.’Äù