Lecture 5- Rene Descartes (1596-1650)
• Method of Doubt
• Attacking the Foundations
• The cogito and the wax example
• “I will devote myself sincerely and without reservation to the general demolition of my
• Why is Descartes taking this on?
• Epistemological question
-Is there anything we can know with certainty?
• Why worry about this?
• Justification: We believe a lot of things without considering our reasons for doing so.
• Truth: We like to believe the things we take to be true really are true in some meaning
• What does this mean, exactly?
+What kinds of things do we believe to be true?
-It is raining today
-I have a cold
-The earth is round
-Apes are primates
-A right angle is 90°
-2 + 2 =4
• i.e. , we believe these to be true based either on:
-If either or both to be subject to doubt, anything founded upon them will be subject to
doubt +Sensation: Begins with Uncontroversial sensory deceptions—i.e. distant sensory perceptions
can be mistaken
• What we perceive and what’s real can come apart in these cases
-This is harder to doubt
“that I am here, sitting...holding this piece of paper in my hands, and so on.” (384)
-it would be crazy to doubt this
-My perceptions are so convincing, I am compelled to believe them
-Can we doubt this?
+The dream argument
• “there are never any sure signs by means of which being awake can be distinguished
from being asleep.” (385)
• My perceptions and reality have come apart again
• What seems real is potentially all in my mind