Arguments for God from reason

Question 1

What are arguments from reason?

Answer 1

A priori arguments based on logic and concepts, not sense experience.

Question 2

What is the Ontological Argument?

Answer 2

A deductive argument claiming God’s existence can be proven by the concept of God alone.

Question 3

Who first proposed the Ontological Argument?

Answer 3

St Anselm of Canterbury (1033–1109) in Proslogion.

Question 4

Anselm’s definition of God:

Answer 4

“That than which nothing greater can be conceived.”

Question 5

Anselm’s First Ontological Argument (Proslogion 2):

Answer 5

A being that exists in reality is greater than one in the mind alone – so God must exist in reality.

Question 6

Anselm’s Second Argument (Proslogion 3):

Answer 6

God is a necessary being – cannot not exist – unlike contingent beings.

Question 7

What is a necessary being?

Answer 7

A being that must exist and cannot not exist.

Question 8

What is a contingent being?

Answer 8

Something that might not have existed – dependent on something else.

Question 9

Who challenged Anselm?

Answer 9

Gaunilo of Marmoutiers – used a parody: the perfect island.

Question 10

Gaunilo’s Perfect Island criticism:

Answer 10

Just because we can conceive of the most perfect island doesn’t mean it exists.

Question 11

Anselm’s reply to Gaunilo:

Answer 11

Islands are contingent; God is necessary. You can’t compare them.

Question 12

Who supported Anselm later?

Answer 12

René Descartes – added clarity and logic to the Ontological Argument.

Question 13

Descartes’ Ontological Argument:

Answer 13

Existence is part of God’s essence – like a triangle must have three sides.

Question 14

Descartes’ analogy of the triangle:

Answer 14

Just as a triangle must have 3 sides, God must exist if he is perfect.

Question 15

Kant’s criticism of Descartes:

Answer 15

“Existence is not a predicate” – it doesn’t add anything to the concept.

Question 16

What is a predicate (Kant’s view)?

Answer 16

A quality that tells us something about the subject (e.g. red, big). Existence isn’t one.

Question 17

Kant’s ‘hundred thalers’ example:

Answer 17

A real 100 coins are not more perfect than imaginary ones – existence doesn’t add value.

Question 18

Hume’s critique of ontological arguments:

Answer 18

You can’t define something into existence – logic alone can’t prove reality.

Question 19

What is reductio ad absurdum?

Answer 19

Anselm’s method: show the opposite leads to contradiction, so his view must be true.

Question 20

What is analytic truth?

Answer 20

True by definition (e.g. a bachelor is unmarried).

Question 21

What is synthetic truth?

Answer 21

Verified by experience (e.g. the cat is on the mat).

Question 22

Is “God exists” analytic or synthetic?

Answer 22

Ontological argument says analytic – critics say synthetic.

Question 23

Plantinga’s modern ontological argument:

Answer 23

God exists in some possible world → must exist in all → exists in this one.

Question 24

What is modal logic?

Answer 24

Type of logic involving possibility, necessity, and worlds – used by Plantinga.

Question 25

How do arguments from reason differ from empirical ones?

Answer 25

A priori; don’t rely on evidence, only concepts.

Question 26

Strength of Ontological Argument:

Answer 26

No need for evidence – it’s self-contained, based on logic alone.

Question 27

Criticism: Logical doesn’t mean real

Answer 27

Just because it’s logically sound doesn’t mean it exists IRL.

Question 28

Gaunilo’s island is a strong challenge

Answer 28

Shows how the logic can be misused for silly conclusions.

Question 29

Anselm’s reply to Gaunilo – weak?

Answer 29

Special pleading? Why does it only work for God?

Question 30

Descartes’ version is vulnerable to Kant

Answer 30

Saying existence is part of a concept doesn’t make it real.

Question 31

Kant’s ‘existence is not a predicate’ is 🔥

Answer 31

Undermines the argument’s central claim.

Question 32

Hume’s critique = savage

Answer 32

You can’t define things into existence – reality requires more than words.

Question 33

Modern modal version = stronger?

Answer 33

Plantinga’s logic avoids some criticisms – but still relies on assumptions.

Question 34

Problem: not persuasive to atheists

Answer 34

Only works if you already accept the concept of God.

Question 35

Strength: doesn’t rely on unreliable senses

Answer 35

A priori logic isn’t affected by experience or change.

Question 36

Problem: assumes shared definition of God

Answer 36

Not everyone agrees on what “greatest conceivable being” means.

Question 37

Why it’s not a strong *proof*

Answer 37

It’s logically valid, but not universally convincing – debate shows it’s not definitive.

Question 38

Helps faith but doesn’t prove

Answer 38

Can support belief, but not compel it – like a “faith-enhancer.”

Question 39

What would make it stronger?

Answer 39

If existence *really* were a predicate – but Kant blocks that.

Question 40

Exam tip: Best way to answer Qs on this topic?

Answer 40

Focus on whether the concept of God makes sense as necessary/analytic, and how convincing the logic is without evidence.