9. Descartes' Rationalism
(October 9, 2012)
What is the status of scientific laws, how certain are they?
Given all experience is private, how do we achieve public knowledge?
What makes memory images, memory images?
Does the world out there resemble my impressions of it?
Are there biases that outline our understanding of the world?
0. Historical and biographical matters
One of the most famous philosophical texts of all time:
An accomplished scientist and mathematician, often called the father of modern philosophy
Interested in the nature of science and in the method of science, a period of great intellectual
Descartes’ Meditations on First Philosophy were published in Latin in 1641; also published in
French after (people started moving away from using Latin as common language in Europe
and people started to write in their own languages)
1. The project:
Descartes’ project was to pull down the degenerate edifice of knowledge and then
rebuild it on firmer foundations, on foundations of certainty (everybody agree on
what is absolutely certain)
“cleaning the Augean stables” – destroy the foundation and start anew. (One of the
great labourers of King Augean was Hercules. Had 3000 cattle kept in stable. Stable
was not cleaned for 30 years. Made Hercules clean the stable in one day. Opened the
doors in the front and made an exit door in the back, led river through the stables to
clean it and start again.)
2. The Method of Doubt:
doubt everything which can be doubted – using the highest possible standards, and see if
there is anything which cannot be doubted
- much of what I “know” is based on memory, however memory is often false. I
should not trust any knowledge based on memory, therefore I should not trust a
great deal of what I know.
b) sense-perception - there are sensory illusions. Eg. looking at a square tower from a distance makes it
- there are dreams. Seems like real life, even though they are not real sensations.
- there is madness. It seems that all sensory “knowledge” of the material (corporeal)
world should be doubted.
- maybe God who is omnipotent is deceiving me. Eg. God is making me think that
2+3=5 although it may not be true. Everytime I do a math problem, God makes me
think I am getting the correct answer each time.
d) postulation of the Evil Genius
- but that would be impossible since a good God would not be a deceiver.
- perhaps there is a “malicious demon” of the utmost power and cunning who
employs all his energy and skill to deceive me in everything.
- The s