From First Meditation:
Descartes’ tried to apply doubt and rationalism to knowing.
Primary Qualities are shape, size, geometry – all quantifiable and more susceptible to measurement.
Secondary Qualities are observer relative – things like smell, color, taste, sound.
Corporeal nature can be deceptive; an evil being could be deceiving us. Basic math cannot deceive.
From Second Meditation:
Like Archimedes, Descartes wanted a fixed point. I think…I know nothing, therefore I am. I must exist to be deceived. I am in error.
Cogito. He grounded philosophy on the ego. Thinking must exist, my essence must exist. How do I know I am a thinking thing? Does logic hold? Does logical inference hold? These are clear and distinct ideas.
From Third Meditation:
Clear and distinct do not get us back to the real world. The flow is in us, not God. Senses exist for corporeal things / substance is measurable. Substance is dualistic. The body is a mechanism, like a clock, determined. Our spiritual substance is free.
1. Arguments for doubting material realm/embodiment.
2. Purely rational; ego is incorporeal.
3. Doubts are contingent things.
4. Composite picture of reality/dualism: Immaterial self and mechanical body. Body is measured and manipulated by our thinking substance.