Meditation 2
Existence of self as thinking thing is not subject to doubt.  (paragraph 3)
But the self is essentially a thinking thing.  (par. 6)
Reason is superior to senses and imagination as evidenced by the fact that reason informs us of the self’s true nature as thinking thing (res cogitons)(par. 7) and the wax’s essential nature as extended thing (res extensa) (par. 11,12,14).

Meditation 3
Note his suggestion that whatever I clearly and distinctly grasp is true.  Why believe this?

Couldn’t God fool us and give us lots of certainty about a belief and yet have it be false?   Descartes must do three things:
 a) prove that God exists
 b) show that God is all good,
 c) that this goodness prevents us from being ultimately  deceived.
(a) and (b) are what he seeks to demonstrate in Meditation 3 and Med. 4 is where he considers (c).

D’s Causal Proof of God’s Existence
Background:
Descartes suggests that existing things have different levels of reality, i.e. a heirarchy of existence!

He’ll call an object’s reality its formal reality and the reality of that which it represents its objective (or presentational) reality.

Descartes causal principle1: all effects have causes.
Descartes causal principle2:  if some effect, e, exists then some cause c must exist and c must have at least as high a “degree of perfection” as e.  (CP2)

The argument in Par. 20-24:
1)I have an idea of an all perfect being (God)
2)My idea of God exists, i.e. as an idea it has formal reality
3)As an object of my idea, God exists (i.e. God exists in my mind)
4)All things have a cause including my idea of God. (CP1)
5)There must be as much reality (or perfection) in a cause than is contained in its effect, both formall and objectively (presentationally)  (CP2)
6)Therefore, there is much perfection in the cause of my idea of God as there is in the effect (formally and objectively)
7) My idea of God has infinite objective (presentational) reality.
8)I am not infinite, so I didn’t cause my idea of God. (by (6))
9)God is the only being with infinite reality, therefore God caused the idea of God.
10)Therefore, God exists.

Meditation 4
In Meditation IV Descartes must show how deception or error is compatible with the existence of an all good God.

Paragraph 4 (end) :  I make errors because my ability to judge isn't infinite.  This is not a design flaw, just a limitation.

Paragraph 5: this isn't entirely satisfactory

Paragraph 8:  My errors in judgement have two causes, understanding and will.

Errors arise from the combination of the will and the understanding.   There is an imbalance, the will is unlimited and the understanding is limited.  (par. 9,10)  Errors arise when I apply the will to things that are beyond the scope of the understanding  or to things that have not been adequately considered by the understanding.

Shouldn't God have made us with a will balanced in proportion to our understanding?

How to avoid error: (par. 18,19):  use the will to decide not to make judgements when the understanding does not warrant them.

Meditation 5
Essence of Material Things
D. is concerned with discussing our knowledge of extension and duration( primary qualities).

(Par. 5) Descartes finds that “innumerable ideas of things which, though they may not exist outside me, can’t be said to be nothing.”  Why does he think this?

The different modes of extension (size, shape, place, etc.) are special in that further truths can be deduced from them.  The same can’t be said about secondary qualities like colour and flavour.

The truths that we can deduce about extensional qualities don’t seem invented.  On the other hand, all we clearly and distinctly perceive about colours and the other sensible qualities is that our ideas of them exist.

Ontological Argument
D. offers a second argument for God’s existence:

 God =def being that has all perfections.

Given this definition, we obtain the following argument:
1. Necessary existence is a perfection.
2. So, by definition, God has necessary existence.
3. Anything that has necessary existence exists.
4. Therefore, God exists.

Memory Problem
Consider  a long proof which is broken down into clear and distinct steps.

When we reach the conclusion we might not remember the initial steps but only that we accepted the initial steps.

Hence, the proof doesn’t rely solely on the clarity and distinctness criterion but also on the reliability of memory.  Only belief in God warrants an appeal to memory.

Meditation 6
On the Existence of Material Objects and the Real Distinctions of Mind from Body

Argument for the existence of material objects:
1) I have ideas of various material objects.
2) These ideas have been caused by some existing thing (myself, God, actual material things, etc.)
3) I have a strong inclination to believe that these ideas of material things are caused by actual material things.
4) This inclination must come from God, my creator.
5) But if my inclinations are false, they are deceptive.
6) But God is not a deceiver.(Med. 4)
7) The ideas must therefore come from actual material things, i.e. material things exist.

Descartes’ argument for dualism:
1.  If it is possible to clearly and distinctly conceive of one thing apart from another, then these two things must be distinct and separable from one another.
2.  I can very clearly and distinctly conceive of myself existing without having to include in myself sense organs, limbs, a body, or in general anything extended or movable in space.
Conclusion: I (thinking thing) must be distinct and separable from my body.
At the end of  Par. 15 D. explicitly acknowledges that although we have reason to believe that there are physical bodies, we don’t have reasons to think that they’re always exactly as the senses represent them.
 
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