Thomas Aquinas was a 13th century Italian Dominican theologian and philosopher who was highly influential in medieval scholasticism. He developed five arguments for the existence of God, known as the "five ways," which attempted to logically prove God's existence from motion, causation, contingency, degrees of perfection, and teleology. His most famous work, the Summa Theologica, synthesized Aristotle's philosophy with Christian theology and discussed topics like virtue, Christ, and the Trinity.

1. Medieval philosophy of
western Europe
THOMAS AQUINAS

2. THOMAS AQUINAS
Italian Dominican theologian Saint Thomas Aquinas was
one of the most influential medieval thinkers of
Scholasticism and the father of the Thomistic school of
theology.
scholasticism is the system of theology and philosophy
taught in medieval European universities, based on
Aristotelian logic and the writings of the early Christian
Fathers and emphasizing tradition
Philosopher and theologian Saint Thomas Aquinas was
born circa 1225 in Roccasecca, Italy

3. THOMAS AQUINAS
Combining the theological principles of faith with the
philosophical principles of reason, he ranked among the
most influential thinkers of medieval Scholasticism.
He wrote many works of philosophy and theology
throughout his life. His most influential work is Summa
Theologica
He was an authority of the Roman Catholic Church and a
prolific writer
Often called "The Universal Teacher," Saint Thomas
Aquinas died at the monastery of Fossanova in italy on
March 7, 1274.

4. Summa Theologica
 It consists of three parts
1. St. Thomas Aquinas believed that the Existence of God can be
proved in five ways ( quinquae viae )
2. St. Thomas Aquinas argues for a connection between the virtuous
man and god ( virtue of ethics )
• It explains how the virtuous act is one towards the
blessedness of the beatific vision. beatific vision is the
ultimate direct self-communication of God to the individual
person
3. Last part of the summa is on Christ
• It was unfinished when Thomas Aquinas died
• In it he shows how Christ not only offers salvation, but
represents and protects humanity on earth and in heaven

5. • Aquinas argued that god, while perfectly united,
also is perfectly described by three interrelated
persons
1. Father
2. Son
3. Holy spirit
• The father generates the son by the relation of self-
awareness.
• This eternal generation then produces an eternal
spirit
• The Christian doctrine of the Trinity holds that
God is one God, but three coeternal (existing with
something else eternally) consubstantial (of the
same substance) persons

6. Quinquae viae The First Way:
Argument from Motion
I. We live in a world in which things are moving.
II. Movement is caused by movers (things that cause motion)
III. Everything that’s moving must have been set into motion by something
else that was moving.
IV. Something must have started the motion in the first place.
V. There cant be an infinite regress of movers
VI. So there must be a first mover, itself unmoved, and that is god.

7. Infinite regress
A sequence of reasoning or justification which can never come to an end.
In chain of reasoning, the evidence for each point along the chain relies on the
existence of something that came before it.
Which in turn relies on something even further back, and so on, with no starting
point.

8. The Second Way: Argument from causation
I. Effects have causes
II. There had to be a first thing that started that started off
chain of causes and that is god

9. The Third Way: Argument from contingency
Necessary being
• A being that has always
existed, that always will
exist, and that can’t not
exist.
Contingent being
•Any being that could
not have existed

10. The Third Way: Argument from contingency
I. He believed that there had to be something that prevented Infinity regress
of contingency
II. There are contingent things
III.Contingent things cause other contingent things, but there cant only be
that.
IV.Because that would mean there is an infinite regress of contingency and a
possibility that nothing might have existed.
V. So there must be at least one necessary thing and that is god

11. The Fouth Way: Argument from
degrees
I. Properties come from degrees
II. In order for there to be degrees of perfection, there
must be something perfect against which everything is
measured.
III.God is perfect

12. The Fifth Way: Teleological Argument
From Greek telos meaning "end“ or “result” of some course of
action.
From Greek logos meaning "reason”
Seeks to prove the existence of God of classical theism by
looking at things in the universe and trying to show they have
been designed for some reason or purpose. E.g. the ear is fit for
hearing and that is it’s purpose.

13. The Fifth Way: Teleological Argument
This brings questions such as ‘has the ear been designed for this
purpose?’ ‘by whom?’ and ‘If not, why is it so suited for hearing?’
‘HOW AND WHY???’
Suggests that by observing certain aspects of the universe are so
perfectly adapted to fulfil their function that they display evidence of
being deliberately designed. This is the evidence which bases this
argument.
That designer can only point to an intelligent designer. GOD.

14. Aquinas’ Arrow Analogy
• 1. An arrow hits a target even though it does not have a mind of
its own. (An effect)
• 2. The archer (someone with a mind of their own) shot the
arrow. (A cause)
• 3. Things in the natural world follow natural laws even though
they do not necessarily have a mind of their own. (An effect)
• 4. Someone with a mind of their own caused the natural world
to behave in this way. He call this someone God. (A cause)

15. “
”
There is nothing on this earth more prized than true
friendship
THOMAS AQUINAS

16. “
”
Sorrow can be alleviated by good sleep, a bath and a glass
of wine
THOMAS AQUINAS

17. “
”
If the highest aim of a captain were to preserve his ship,
he would keep it in port forever
THOMAS AQUINAS

18. “
”
The things that we love tell us what we are
THOMAS AQUINAS

19. “
”
To one who has faith, no explanation is necessary. To one
without faith no explanation is possible
THOMAS AQUINAS

20. THANK YOU FOR YOUR ATTENTION