Summa Theologica

Philosophy 1

Spring, 2002

G. J. Mattey

Thomas Aquinas

• 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 itself2. So, nothing in nature can be the efficient

cause of itself3. The series of efficient causes cannot go on

infinitely4. So, there is a first efficient cause5. The first efficient cause is God6. So, God exists

The Argument from Contingency

1. Everything in nature can not be2. What can not be sometimes is not3. If everything can not be, then once nothing existed4. What exists only comes from what exists already5. So, if everything can not be, then nothing would

exist6. So, some being cannot not be7. A being that cannot not be is God8. So, God exists

The Argument from Gradation

1. All things in nature come in degrees2. If something comes in degrees, it must be

comparable to a maximum3. The maximum in a genus is the cause of all that

falls into the genus4. So, there must be a maximum of goodness and

all perfections5. The maximum of perfections is God6. So, God exists

The Argument from Governance

1. Natural bodies act for an end

2. Acting for an end depends on a purpose

3. A purpose depends on knowledge

4. Many beings that act for an end lack knowledge

5. 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

• The argument from evil1. If God exists, then goodness is infinite, and

there is no room for evil in the world2. There is evil 3. So, God does not exist

• But the existence of evil is compatible with that of God

• God allows evil for the production of good