Descartes viewed that many of our beliefs rest on shaky foundations. To find truth knowledge, we must doubt as much as we can find facts we cannot doubt.

Doubtable Facts

  • I can doubt that my professor is my professor
    • Could be an evil twin
  • I can doubt that I am awake
    • Could be in a vivid dream
  • I can doubt that I have hands
    • Could be in a coma
  • I can doubt that I have a brain
    • Could be that I am a soul and my perceptions are shaped by some soul world
  • I can doubt that there is an external world
  • I can doubt that I’m in pain

Undoubtable Facts