DESCARTES' MEDITATIONS - STUDY GUIDE
[Page numbers are from the Penguin Edition]
He realises most of his knowledge (esp. for science) is unreliable, and the only way is to rebuild it from the foundations.
2. Systematic Doubt
He proposes to destroy all his opinions, and only accept as knowledge those which are totally certain, rejecting the rest.
Opinions should be rejected if there is any way in which they could be false.
3. Mistrusting the Senses
The senses are instantly rejected, because they are obviously occasionally deceptive, and they certainty can't be proved.
4. Madness and Dreams
The idea that daily experience is all wrong seems mad, but then he realises that dreams are a sort of daily madness, and he
believe them. There is no clear proof that he is not currently dreaming.
5. Reality remixed
Although he may be dreaming, perhaps he can deduce what reality is like - it is the components out of which dreams are
made. The major components (hands and eyes) may be imagined, but the basics must actually exist.
The most basic components (3+2=5, squares have four sides) are reliable, because they don't require any particular things to
exist to make them true.
7. Deception by God
But it is possible that an omnipotent God exists, and such a being could deceive him about maths, so it isn't certain.
8. Deception by Nature
If there isn't a God then he is just the product of chance, which makes his maths even less reliable.
9. Deception by a Demon
To force himself to face up to his doubts, he imagines an evil demon who systematically deceives him about everything.
10. Despair and Solipsism
He finds he is reaching total uncertainty. He must doubt his memory, and whether he has a body. He may be inventing
reality himself, in which case he is the only thing which exists.
11. The Cogito
There is one certainty - in order to be deceived, he himself must exist, and that must be true whenever he is thinking.
12. The Cartesian Ego
So what is he? 'Rational animal' begs too many questions. The demon makes his body doubtful. So he is just "a thing which
thinks", but that is only while he is actually thinking.
He wants to extend his knowledge, but realises that imagination is no help, because it just pictures physical objects, which he
already knows are open to doubt.
Reality may be uncertain, but he is definitely having a range of experiences, and his self ("I", the being who is having the
experiences) must also be certain.
15. Understanding Wax
His knowledge of physical objects (e.g. wax) may seem to come through his senses, but when sensations change it his
judgement which arrives at the knowledge. His understanding is the essential part of him, not his senses.
16. "Seeing" dummies
We say that we "see" things, but actually we are making a judgement, as when we see clothed people, and judge that they are
human rather than mechanical dummies.
He is certain of his own existence, but what makes him so certain? Because he is "clear and distinct" about it, and this test
has never let him down. So clear and distinct conceptions are true.
18. Categories of Thought
The next step is to categorise his thinking - into ideas ('concepts'), ideas with added attitude ('propositional attitudes'), and
judgements. Error is entirely found in judgements, mainly about the way concepts match up with so-called 'reality'.
19. Categories of Ideas
Next he categorises the ideas/concepts - into innate, adventitious and invented. Innate ideas come from his own nature,
adventitious ideas from outside himself, and invented ideas are his own creation - but are these three separate?