1. René Descartes, Meditations Introduction to Philosophy Jason M. Chang

2. Learning Outcomes 1. Background 2. Descartes’ project in the Meditations 3. Descartes’ method 4. “Cogito, ergo sum” 5. The appearance/reality gap

3. Background Biography Meditations on First Philosophy (1647) Rene Descartes 1596-1650

4. Background Historical context o Scientific revolution o Expansion of human knowledge

5. Descartes’ project in the Meditations

6. Descartes project Background Knowledge = justified true belief Foundationalism o Definition o Example1, Example 2 Example1Example 2

7. x y z I know that x + y = 90 degrees Z = 90 x + y + 90 = 180 x + y = 90 x + y + z = 180 FOUNDATIONAL BELIEFS

8. C3 is 3 C2 = 1 C1 = 2 A2 and B2 are combo of 2 and 3 A1 = 1 B1 = 3 B2 = 2A1 = 3 B3 = 1A3 = 2 Ken Puzzle

9. Descartes project Problem of doubtful beliefs Descartes’ question o What can serve as a foundation for scientific truths? Aim of Meditations Published in 1647

10. Descartes’ method

11. What scares Descartes “It is now some years since I detected how many were the false beliefs that I had from my earliest youth admitted as true, and how doubtful was everything I had since constructed on this basis.”

12. Descartes’ method “If in doubt, throw it out” Method of “Cartesian doubt” o What it is o Its aim o Methodological NOT genuine doubt

13. Are there any beliefs that cannot be doubted that can serve as a foundation for scientific knowledge? Descartes’ method

14. Candidate #1: Beliefs derived from senses Senses are deceptive The dream argument

15. Descartes’ method Descartes’ Dream Argument (P1) I often have perceptions when I am dreaming like the ones I have now. (P2) There is no definite signs to distinguish between dream experience and waking experience. Therefore, (C) It is possible that I am dreaming right now and that my perceptions are false.

16. Descartes’ method Candidate #2: Beliefs derived from reason Evil demon argument

17. Descartes’ method Descartes’ Evil Demon Argument (P1) It is possible that an evil demon is deceiving me when I reason to conclusions. Therefore, (C) It is possible that the conclusions I derive from reason are false.

18. Descartes seems to have shown that there are no indubitable beliefs that can serve as a foundation for science. Descartes’ method

19. What this means Wrong interpretation Right interpretation o No solid foundation for knowledge o Beliefs from science no better than beliefs from faith o Skepticism (???)

20. “Cogito ergo sum”

21. “Cogito, ergo sum” Translation The passage “Let [the evil demon] deceive me as much as he will, he can never cause me to be nothing so long as I think that I am something. So that after having reflected well and carefully examined all things, we must come to the conclusion that this proposition; I am, I exist, is necessarily truth each time that I pronounce it or that I mentally conceive of it.”

22. “Cogito, ergo sum” Descartes’ reasoning (P1) Even if we assume that there is a deceiver, from the very fact that I am deceived it follows that I exist. (P2) More generally, whenever I think (e.g., feel, sense, imagine, reason), it is affirmed I exist. (P3) I think. Therefore, (C) I exist.

23. “Cogito, ergo sum” Others things that cannot be doubted o Experience claims vs. Reality claims o Experience claims cannot be doubted

24. The appearance/reality gap

25. How can we know that objects as they appear to us is how objects really are?

26. The appearance/reality gap Clear and distinct ideas “Myself as an existing thing” is clear and distinct Ideas and perceptions that are clear and distinct are true I have a clear and distinct idea of perfection

27. The appearance/reality gap Descartes’ argument for God (P1) The idea of perfection must have a cause. (P2) I am an imperfect being. (P3) It is impossible for an imperfect being to be the source of the idea of perfection. So, (P4) I cannot be the source of the idea of perfection. Therefore, (C) The source of the idea of perfection must be a Perfect Being (God).

28. The appearance/reality gap Descartes’ argument bridging the gap (P1) God, who is perfect, cannot be a deceiver. So, (P2) God would not mislead me when I perceive something clearly and distinctly. Therefore, (C) Whenever I perceive something clearly and distinctly, it must be true.

29. The appearance/reality gap Part of Descartes’ legacy How can we know that objects as they appear to us is how objects really are?