Review: Descartes' Project
- Descartes is seeking a certain foundation for his edifice of knowledge.
- His assaults on the senses and the apriori show that knowledge from these sources cannot be known with certainty.
- Ultimately, the only thing we can know with certainty is the cogito ("I think").
Time Out: Reflection on Descartes' Legacy
- Defining our True Essence: A Thinking Thing
- Descartes' account of the human person as a thinking thing is the most influential account of dualism.
- Dualism is the view that a human person has two components: an immaterial mind and a material body.
- The "Ego-Centric" Predicament
- The "Ego-Centric" Predicament is the difficulty with trying to penetrate the screen of perception. That is, it is difficult to see how we can get beyond our perceptions of the world to what the world is actually like.
- The difficulty for Descartes is avoiding solipsism (i.e., the view that nothing is real except my mind and the thoughts taking place in my mind).
Rebuilding the Pyramid
- Goal: Establish We Can Trust Clear and Distinct Thoughts and Perceptions
- Available Resources: Contents of the Mind
- Concept of God
- Ancient Principles
Next Step: Establishing God's Existence
- Reality comes in degrees.
- Cause must have as much reality as effect.
- An idea's source must have as much formal reality as the idea's own objective reality. For example, consider an apple. My idea of an apple has as its content redness, roundness, sweetness, etc. This is the objective reality of my idea. According to this principle, the source of my idea must be red, round, and sweet. That is, the formal reality of the source of my idea must be red, round, and sweet.
Next Step: Clear and Distinct Ideas Must be Accurate
- My idea of God must come from God!
- This is based on the third of the ancient principles. My idea of God has as its objective reality things such as omnipotence, omniscience, all goodness, etc. According to the principle, the source of this idea must have as its formal reality omnipotence, omniscience, and all goodness.
Next Step: Establishing Truth of Beliefs about the World
- God exists and is not a deceiver.
- Therefore, I am not deceived about my clear and distinct ideas.
- If clear and distinct perceptions of the world are accurate, then the world must really exist as we (generally) believe it does.
- Descartes has rebuilt his pyramid of beliefs on the basis of his one certain belief, the cogito.
The Problem with Descartes' Project: The Cartesian Circle
- The Cartesian Circle--Start with the idea of God and the ancient principles. Reason that the idea of God cannot come from Descartes but must come from God. Therefore, God exists. Therefore, our clear and distinct ideas are true. However, it seems that we must already believe that our clear and distinct ideas are true in order to believe that the ancient principles are true. So Descartes reasons in a circle.
- Why suppose that the ancient principles are correct?
- The justification appears to be that they are believed clearly and distinctly. Descartes appeals to the "light of nature".
- But the reliability of things understood clearly and distincly is the very thing we must establish!!!
Citation: Ramsey, W. (2006, September 19). Lecture 24 Notes. Retrieved June 20, 2013, from Notre Dame OpenCourseWare Web site: http://ocw.nd.edu/philosophy/introduction-to-philosophy-1/lectures/lecture-24-notes.
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