St. Thomas Aquinas
Mr. Dunn
Basic facts about Thomistic philosophy
• Integration of Aristotle with Christianity
• Natural Theology, which is the use of reason
to articulate truths of revelation (the Bible and
the Church)
• Everything is ordered in a hierarchy with God
at the top.
• God is that toward which everything and
everyone ought to be directed
Aristotle + Christianity = Aquinas
• By the thirteenth century, there was a trend
towards focusing on the natural world as
opposed to calling it evil as Augustine did.
• The philosophy of Aristotle saw a resurgence.
• Aquinas’ goal was to Christianize Aristotle.
• Aquinas also wanted to show how reason and
faith can work together to explain our world
and to explain how we should live our lives in
accordance with our nature.
Form and Essence
• Like Aristotle, Aquinas believed that the form
of things are within substances themselves,
not in another world. He called these essences
(what makes things what they are).
• We can use observation and reason to
understand essence. (similar to Aristotle)
Natural theology
• The philosopher uses reason alone.
• The theologian accepts revelation (the Bible and
the Church) as authority.
– Revealed theology- truths accepted purely on faith
(God sent His only son to save us from sin)
– Natural theology- reason can corroborate revelation
(Nothing can exist unless God (the first cause and
necessary being) exists)
– When faith can’t be explained by reason, then we
simply need to accept them based on faith. Yet, when
it’s possible to understand revelation by using reason,
we should.
Actuality vs. Potentiality
• The being of everything in this world has actuality and
potentiality.
• God is the only 100% actual being.
– Everything else has a different degree of actuality. What’s left is
potentiality.
– NOTE: Aquinas never used percentages. I’m simply using these
to illustrate the concept.
– Humans- 85% actual being/ 15% potential being
– House fly- 35% actual being/ 65% potential being
• There is no existence without essence and no essence
without existence.
• Therefore, there needs to be an actual being in order for
any potential being to exist. Therefore, God exists.
The soul is the essence of…
• One difference between Aristotle and Aquinas
– The soul, according to Aristotle, is the form (or the
essence) of the body
– The soul, according to Aquinas, is the form (or the
essence) of the person himself or herself.
– In other words, Ben Gerke’s soul exists alongside the
body to make Ben who he is (according to Aristotle)
– In other words, Ben Gerke’s soul exists alongside Ben
Gerke’s personhood to make Ben who he is (according
to Aquinas)
• A confusing part of this is that Aquinas believes that a
person’s body is a part of personhood, and the personhood
and the body are always united.
Aquinas’ cosmological proofs for the
existence of God
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Five proofs for the existence of God
All begin with observations of the natural world
Example- the second proof
Observe that baby chicks come from mother
chickens.
• All efficient causes must have a first cause or else
there would be no effects. Therefore, there is a
first cause and that first cause is God.
Teleological Morality
• All of Aquinas’ thoughts are teleological,
especially his ethics.
• Every action has an end or a purpose (final
cause).
• All final causes have an ultimate final cause which
is God.
• God, as the final causes, bestows meaning on
every action that exists since every action
ultimately leads to God. Thus, without God, all
actions would be meaningless. Also, human life
itself would be meaningless.
Natural Law
• Aquinas defined Natural Law as God’s law applied
to human beings.
• God gave human beings freedom; therefore
humans are free to obey the natural law or not.
• Going against God also goes against everything it
means to exist and everything it means to be a
human being.
• In Thomas’ moral philosophy, both reason and
Biblical revelation lead to the same conclusion.
Thus natural law stems from natural theology.
Scholasticism
• Aquinas’ theology is part of scholasticism, which
is the thirteenth century quest to explain Catholic
theology through reason.
• This emphasis on observing the natural world
began a movement which ironically would
eventually reject speculative thinking about God
and eternity. This movement flourished during
the Renaissance.
• The Renaissance was characterized by a
fascination of this world and a disdain for
speculative metaphysics.