Descartess Meditations 4-6
Meditation 4 Is God a deceiver?
Problem: If I was made by a really good God who can do anything, why cant I be relied on to reach correct conclusions on all questions and always do the right thing?
Answer: There is nothing wrong with me, I am just limited. My mind works perfectly well, but has limited powers. Only when it tries to go beyond these limits do I make mistakes. I can try to go beyond these limits because God has given me a free will. The will has a greater range than my intellect.
Objection: Why didnt God match my intellect and my will, or provide a better warning that the intellect is so limited? (If Jesus is this warning, why didnt God send him sooner and to all parts of the world?)
Meditation 5 The "Cartesian Circle"
Problem: To prove that God is not a deceiver, that the mind is at least somewhat reliable, Descartes shows that what we clearly and distinctly perceive to be true must be true. It must be true because otherwise God would be a deceiver. He cannot be a deceiver because then He would be imperfect. But we can clearly and distinctly see that God is perfect. But when we clearly and distinctly see that God exists, how do we know that this perception is reliable? Doesnt Descartess argument go in a circle?
Answer: In a sense we cannot prove that God exists, or that what we clearly and distinctly perceive is true, but when we attend to the proofs of Gods existence and understand these proofs, we cannot doubt that God exists. This is enough for any sane person. We have actual certainty. So-called metaphysical or absolute certainty is not relevant.
Objection: Why then bother with the whole demon hypothesis, or the Meditations, if we are so ready to accept common sense? (Perhaps proving that I exist, my body exists, etc. is really not the point of the Meditations, therefore.)
Meditation 6 The Mind-Body Problem
Problem: I am a thinking thing, a mind or soul. This can be thought of existing without the body, e.g. after death, therefore the mind is not essentially part of or connected to the body. And the essence of the mind is thinking, while the essence of physical things is being extended (i.e. three-dimensional). And if two things are the same then they must have all the same properties, yet the mind has the property of undoubtedly existing (I think therefore I am) while the body's existence can be doubted (I could be deceived about it). The mind is not a physical, extended thing. Yet it is connected to the body; it feels my bodys pains, thirst, itches, tickles, etc. and when I make up my mind to walk out the door, my body gets up and goes. How can a non-physical, ghostly, purely intellectual mind connect with a purely physical body?
Answer: The connection must be in the brain. Objection: The question was not "Where is it?"