Transcript Summa Theologica - University of California, Davis

Summa Theologica
Philosophy 1
Spring, 2002
G. J. Mattey
Thomas Aquinas
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Born 1224
From Roccasecca, Italy
Studied Aristotle in Italy
Studied in Paris
Died 1274
Pope Leo XXIII declares
him “chief and master
among all the scholastic
doctors,” 1879
Aquinas’s Contributions
• Applied newly-recovered philosophy of
Aristotle to Christian theology
• Challenged the theology of Augustine
• Distinguished clearly between what can be
demonstrated by reason without revelation
and what cannot
• Gave arguments for the existence of God
from the existence of the universe
The Recovery of Aristotle
• The logical works had been translated into Latin
by Boethius in the 5th and 6th centuries
• Only two were widely available by the 12th
century
• At that point, many Greek and Arabic texts were
translated
• The rest of Aristotle’s works became available
• The Arabic commentaries were translated as well
– Avicenna (Ibn Sina, 980-1037)
– Averroes (Ibn Rushd, 1126-1198)
Reason and Revelation
• It can be argued that philosophy reveals all
of being without recourse to revelation
• But there must be revealed knowledge as
well
• The ends of God surpass reason, and
humans must know what these are
• And what can be known through reason
might be known only to a few
Theology
• There is a science, theology, of what is known
through revelation
• It is one science because all that it treats is
divinely revealed
• It includes both the theoretical and the practical
• It is more certain than the lower sciences because
its source is the infallible God
• It draws on philosophy only to clarify its teachings
The Practice of Theology
• The subject-matter of theology is God
• It uses reason to argue from first principles,
which are articles of faith
• Thus it uses arguments from authority,
which are the strongest arguments when the
authority is divine
• Its claims cannot be disputed with those
who reject all articles of faith
The Investigation of God
• There are three divisions of the treatment of God,
concerning
– The divine essence
– The distinction of three Persons in one God
– The creatures as they proceed from God
• The treatment of the divine essence has three parts
– Whether God exists
– How God exists
– The operations of God (knowledge, will, power, etc.)
Is God’s Existence Self-Evident?
• One knows something self-evidently when
the predicate is included in the essence of
the subject (Man is an animal)
• Existence is included in the essence of God
• But we do not know God’s essence
• So we must infer God’s existence from
God’s effects in nature
The Ontological Argument
• Anselm argued that one knows God exists when
one understands what God is
• Many people do not understand God as something
than which nothing greater can be thought
• Understanding this only means that what it
signifies exists in the mind
• The argument must beg the question against the
atheist, for it can only assume that this something
exists in reality
Proving the Existence of God
• We prove God’s existence as the cause of
effects in nature
• If the effect exists, its cause must exist
before it does
• But this kind of argument reveals the cause
only to a limited extent, as the effects are
finite and God is infinite
The Argument From Motion
1. An object cannot both move and be moved in the
same respect and the same way
2. So, if an object is moved, there is a distinct
mover
3. The series of movers cannot go on infinitely
4. So, there is a first mover which is not moved
5. The unmoved mover is God
6. So, God exists
The Argument from Causality
1. Nothing can be prior to itself
2. So, nothing in nature can be the efficient
cause of itself
3. The series of efficient causes cannot go on
infinitely
4. So, there is a first efficient cause
5. The first efficient cause is God
6. So, God exists
The Argument from Contingency
1. Everything in nature can not be
2. What can not be sometimes is not
3. If everything can not be, then once nothing
existed
4. What exists only comes from what exists already
5. So, if everything can not be, then nothing would
exist
6. So, some being cannot not be
7. A being that cannot not be is God
8. So, God exists
The Argument from Gradation
1. All things in nature come in degrees
2. If something comes in degrees, it must be
comparable to a maximum
3. The maximum in a genus is the cause of all that
falls into the genus
4. So, there must be a maximum of goodness and
all perfections
5. The maximum of perfections is God
6. So, God exists
The Argument from Governance
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Natural bodies act for an end
Acting for an end depends on a purpose
A purpose depends on knowledge
Many beings that act for an end lack knowledge
So, those beings are directed by a being that has
knowledge
6. God is the being who directs all natural things
7. So, God exists
The Problem of Evil
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The argument from evil
1. If God exists, then goodness is infinite, and
there is no room for evil in the world
2. There is evil
3. So, God does not exist
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But the existence of evil is compatible
with that of God
God allows evil for the production of good