This week:

• Descartes's Ontological Argument
• Make a start on Descartes's Dualism

This week we'll look at an argument FOR the existence of God.

We'll look at arguments AGAINST the existence of God in a later week.

Two main forms of argument for the existence of God:

COSMOLOGICAL - "God must be the cause of this or that phenomenon"

ONTOLOGICAL - "Given his essence or nature, God must exist"

Descartes's arguments for the existence of God:

• Cosmological argument(s) in the 3rd Meditation
• Ontological argument in the 5th Meditation

THE ARGUMENT

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property
2. We can clearly and distinctly perceive that existence belongs to the essence of God
3. So God exists

PREMISE 1:

• If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property.

By thinking carefully, Descartes believes we can come to know things about the nature or ESSENCE of a thing, even if we do not yet know whether that thing EXISTS.

“When, for example, I imagine a triangle, even if no such figure exists... anywhere outside my thought, there is a determinate nature, or essence, or form of the triangle which is immutable and eternal, and not invented by me or dependent on my mind. This is clear from the fact that various properties can be demonstrated of the triangle, for example that its three angles are equal to two right angles, that its greatest side subtends its greatest angle, and the like”

Descartes Meditation V, CSM II:45, AT 7:64.

The idea of a (Euclidean) triangle whose internal angles do not sum to 180° is contradictory.

So the sum of the internal angles of a triangle is 180°.

And we can know this even though we don't know whether any triangle actually exists.

"But if the mere fact that I can produce from my thought the idea of something entails that everything which I clearly and distinctly perceive to belong to that thing really does belong to it, is not this a possible basis for another argument to prove the existence of God?"

Descartes Meditation V, CSM II:45, AT 7:65.

PREMISE 2:

• We can clearly and distinctly perceive that existence belongs to the essence of God.

"[M]y understanding that it belongs to [God's] nature that he always exists is no less clear and distinct than is the case when I demonstrate of any shape or number that some property belongs to its nature. Hence, even if it turned out that not everything on which I have meditated in these past days is true, I ought still to regard the existence of God as having at least the same level of certainty as I have hitherto attributed to the truths of mathematics."

Descartes Meditation V, CSM II:45, AT 7:65-6.

Usually, Descartes distinguishes questions about a thing's essence from questions about its existence. But the case of God is special:

"It is quite evident that existence can no more be separated from the essence of God that the fact that its three angles equal two right angles [i.e. 180°] can be separated from the essence of a triangle, or that the idea of a mountain can be separated from the idea of a valley. Hence it is just as much of a contradiction to think of God (that is, a supremely perfect being) lacking existence (that is, lacking a perfection), as it is to think of a mountain without a valley."

Descartes Meditation V, CSM II:46, AT 7:66.

DESCARTES'S ARGUMENT FOR PREMISE 2:

• The essence of God is that of a being with every perfection.
• Existence is a perfection.
• So, existence belongs to the essence of God.

To better understand the overall argument, let's consider some objections that have been raised against it.

OBJECTION 1

"Existence is not a property." (Gassendi, Kant)

Imagine Barack Obama.

Now imagine Barack Obama as existing.

The lesson: there is no difference between an idea of a thing and the idea of that thing existing.

One way to press the objection:

If existence IS a property, it seems it must be a property that is contained in ALL our clear and distinct ideas of things!

And if so, we can easily construct PARODIES of Descartes's argument - arguments which parallel Descartes's argument but establish absurd conclusions.

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property
2. We can clearly and distinctly perceive that existence belongs to the essence of Willy Wonka
3. So Willy Wonka exists!

It seems Descartes has to either admit that existence is NOT a property or find some difference between his argument and the parody.

Descartes tries for the latter by distinguishing different GRADES of existence.

The clear and distinct idea of any thing contains POSSIBLE existence. But all that follows from this is that the thing COULD exist, not that it does.

The clear and distinct idea of God, on the other hand, contains NECESSARY existence. What follows from this is not just that he could exist, but that he DOES.

Properly understood, then, the argument for God is:

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property
2. We can clearly and distinctly perceive that necessary existence belongs to the essence of God
3. So God exists

And the closest we can get for Willy Wonka is:

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property
2. We can clearly and distinctly perceive that possible existence belongs to the essence of Willy Wonka
3. So Willy Wonka could exist

OBJECTION 2

"All that Descartes can legitimately claim is that God has the property of necesssary existence IF HE EXISTS." (Caterus)

One form of this objection begins by offering another parody.

Take the idea of a SUPER WILLY WONKA: the idea of Willy Wonka, but with the property of necessary existence.

The idea of Super Willy Wonka contains not just possible existence, but necessary existence.

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property
2. We can clearly and distinctly perceive that necessary existence belongs to the essence of Super Willy Wonka
3. So Super Willy Wonka exists!

What's gone wrong? Perhaps Descartes should have said:

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property IF IT EXISTS

But then the argument ought to be:

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property if it exists
2. We can clearly and distinctly perceive that necessary existence belongs to the essence of God
3. So God (necessarily) exists IF HE EXISTS.

Descartes needs to deny that we can clearly and distinctly perceive that necessary existence belongs to the essence of Super Willy Wonka.

But how can he do that without undermining his claim that we can clearly and distinctly perceive that necessary existence belongs to the essence of God?

There needs to be a difference between our idea of God and our idea of Super Willy Wonka.

Some options:

• Our idea of Super Willy Wonka is assembled by the intellect, where our idea of God is not.
• Our idea of Super Willy Wonka is not clear and distinct, where our idea of God is.

But the objection can take a different form. We don't need to argue that Descartes's premise 1 is false. We can just ask: is there any reason to think it is true?

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property

What about Descartes's TRUTH RULE?

• Whatever we can clearly and distincly perceive to be true is true.

But all this entails is:

• If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that property does belong to the essence of that thing

And this only seems to give us:

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property IF IT EXISTS

This is not a KNOCK-DOWN objection. Rather, it raises a CHALLENGE:

Descartes, explain why we should accept your first premise!

THE MIND-BODY PROBLEM

What is the relationship between mental entities and physical entities?

Options:

• DUALISM: mental entities are distinct from physical entities.
• PHYSICALISM: mental entities are physical entities.

Different questions can be raised about entities in different ONTOLOGICAL CATEGORIES.

• SUBSTANCES are particular things that persist through time and change their properties. An example: a piece of paper.

• EVENTS are things that happen or occur. An example: a piece of paper's turning yellow.

• PROPERTIES are kinds, types, or qualities that can be instantiated. An example: being yellow.

• SUBSTANCE DUALISM: mental substances are distinct from physical substances.

• EVENTS DUALISM: mental events are distinct from physical events.

• PROPERTY DUALISM: mental properties are distinct from physical properties.

Descartes was a substance dualist. He thought that mind and body are radically different kinds of substance.

Descartes is associated with three arguments for substance dualism:

1. The argument from doubt
2. The epistemological or "real distinction" argument
3. The argument from indivisibility

THE ARGUMENT FROM DOUBT

In the Discourse on the Method, after establishing that he exists - the famous cogito - Descartes asks what this thing that exists is:

"I saw that while I could pretend that I had no body and that there was no world and no place for me to be in, I could not for all that pretend that I did not exist. I saw on the contrary that from the mere fact that I thought of doubting the truth of other things, it followed quite evidently and certainly that I existed; whereas if I had merely ceased thinking, even if everything else I had ever imagined had been true, I should have had no reason to believe that I existed. From this I knew I was a substance whose whole essence or nature is simply to think, and which does not require any place, or depend on any material thing, in order to exist."

Descartes Discourse, CSM I:127, AT 6:32-3.

The argument:

1. I cannot doubt that I exist
2. I can doubt that my body exists
3. So I am not my body

Premise 1 seems to claim that I have a property that premise 2 claims MY BODY lacks, namely:

The property of being such that I cannot doubt its existence.

If so, the conclusion follows by the INDISCERNIBILITY OF IDENTICALS:

• If two things are the same thing then they have exactly the same properties.

(Note that this is not the same as the much more controversial IDENTITY OF INDISCERNIBLES:

• If two things have exactly the same properties then they are the same thing.)

But it is not a good argument!

1. I cannot doubt that J. K. Rowling is J. K. Rowling
2. I can doubt that Robert Galbraith is J. K. Rowling
3. So J. K. Rowling is not Robert Galbraith

But J. K. Rowling IS Robert Galbraith!

This is another PARODY.

It tells us that Descartes's argument from doubt cannot be sound.

But it does not tell us where the flaw lies.

Some options:

• The Indiscernibility of Identicals is false
• One of the two premises is in fact false
• Premise 1 does not claim I have a property that premise 2 claims my body lacks

By the time of the Meditations, Descartes realised that the argument from doubt was flawed, and emphasis is instead on the epistemological argument, which we'll look at next time.

Descartes's ontological argument:

1. If we can clearly and distinctly perceive that a property belongs to the essence of a thing then that thing has that property
2. We can clearly and distinctly perceive that existence belongs to the essence of God
3. So God exists

Descartes blocks certain parodies of this argument by distinguishing between POSSIBLE and NECESSARY existence. It's necessary existence that we can clearly and distinctly perceive to belong to the essence of God, he thinks.

It is unclear whether he can block other parodies, however, like that involving the idea of Super Willy Wonka. And even if he can, there is a residual question as to what entitles him to the conclusion that God exists, rather than the conclusion that God exists IF HE EXISTS.

We can also use parodies to show that one of the arguments Descartes gives for SUBSTANCE DUALISM, the argument from doubt, is no good.