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DESCARTES (1596-1650)

DESCARTES (1596-1650). Meditations on first philosophy. Purpose: To Obtain Absolute Certaint y. Belief? Knowledge? Truth? Justification?. What is a Belief?. A belief is the acceptance of a given affirmation or proposition as true.

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DESCARTES (1596-1650)

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  1. DESCARTES (1596-1650) Meditations on first philosophy

  2. Purpose: To Obtain Absolute Certainty Belief? Knowledge? Truth? Justification?

  3. What is a Belief? A belief is the acceptance of a given affirmation or proposition as true. An Affirmation or proposition is a claim that is either true or false. Examples: “Today is Monday.” “It is snowing outside.” Beliefs are held with degrees of strength.

  4. What is Truth? Some proposition is true if it describes the way the world is (i.e., REALITY). A proposition is true if it corresponds to reality. Example: the proposition “today is Monday” is either true or false depending on what day it is.

  5. What is Knowledge? If you hold a BELIEF and you have good reason to hold the belief (i.e., JUSTIFICATION or EVIDENCE) and if the belief is TRUE, we can conclude that you KNOW the belief. It may end up that your belief is wrong (i.e., FALSE) so that you don’t KNOW what you BELIEVED. It may end up that your belief is TRUE but not for the reasons that you thought and therefore you didn’t know your belief.

  6. What is Justification? A given proposition serves as justification or evidence for another proposition if the truth of the former makes the truth of the latter more likely. Therefore, proposition p is evidence for proposition q, if p‘s truth makes q’s truth more likely. John’s fingerprints on the gun is evidence for the proposition “John committed the murder” since the truth of the former makes the it more likely that the latter is true. Hence, “it is evidence FOR the truth of…”

  7. Rationality Beliefs: Degrees Evidence: Degrees The strength of our beliefs should be proportional to the evidence we have for the truth of the belief.

  8. Absolute Certainty Absolute certainty is achieved if one has Absolute evidence for the truth of a belief. Absolute certainty must eliminate all reasonable doubt and even ALL POSSIBLE DOUBT! If it is possible to doubt a belief then we are not absolutely certain that it is true.

  9. Certainty Probable assurance 0-100% probability. Can anyone be 100% assured of the truth of anything?

  10. What Can We Doubt and Why? We can doubt that what we see is really there. Why? We might be hallucinating; we might be dreaming; We might be tricked by an evil genius; we might be tricked by God; we might be in a Matrix and hooked up to an elaborate software that is putting all our experiences into our minds.

  11. Skepticism About My Perceptions Radical Skepticism Can we be certain of reality? How do we know for certain that the external world exists? The external world is the world I assume to be outside of my thoughts. If I perceive a tree then there is a tree. Is this a good argument. How can I be certain that some evil genius is not causing me to see a tree even if there is no tree in front of me.

  12. “I think, therefore I am” Even if we are being tricked by a power agent of some kind, she cannot fool me about my existence or about my experiences. The only thing that Descartes can be absolutely certain about is that he is a thinking thing. I can be certain therefore about all my thoughts.

  13. The Gap Internal World External World Thought Mental Phenomena Phenomenology Experiences Outside of thought Physical world Causes of my experiences

  14. Thought is Certain Thought is anything that goes on in the mind Ideas Perceptions Feelings Sensations Emotions Doubts Etc.

  15. Thoughts are Immediately Known Thoughts are abstract Mind Soul Not physical Not extended Spiritual

  16. Knowledge of the External World I know the external world through my thoughts. I see a tree therefore there is a tree. I assume that the thoughts I have are caused by things in the external world. This knowledge is uncertain because it is not immediate.

  17. Mind Body Problem Mind Body Thoughts Abstract Mind Spiritual Soul Intangible Non-divisible Non-spatial Actions Concrete Brain Non-Spiritual Body Tangible Divisible Extended

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