Skepticism The Dreaming Argument
The First Meditation All that I have, up to this moment, accepted as possessed of the highest truth and certainty, I received either from or through the senses. I observed, however, that these sometimes misled us; and it is the part of prudence not to place absolute confidence in that by which we have even once been deceived…
The First Meditation …but it may be said, perhaps, that, although the senses occasionally mislead us respecting minute objects, and such as are so far removed from us as to be beyond the reach of close observation, there are yet many other of their presentations, of the truth of which it is manifestly impossible to doubt…
The First Meditation …all this would be eminently reasonable if I were not a man, and not accustomed to sleeping at night… How often have I dreamt that I was in these familiar circumstances, that I was dressed, and occupied this place by the fire, when I was lying undressed in bed? …considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming. -Descartes, Meditations
The Dreaming Argument • I can’t rule out the possibility that I’m dreaming. • If (1), then I can’t know anything about the external world. • [So] I can’t know anything about the external world.
The Dreaming Argument Nevertheless it must be admitted at least that the objects which appear to us in sleep are, as it were, painted representations which could not have been formed unless in the likeness of realities… painters themselves, even when they study to represent sirens and satyrs by forms the most fantastic and extraordinary, cannot bestow upon them natures absolutely new, but can only make a certain medley of the members of different animals. -Descartes, Meditations
The Dreaming Argument • I can’t rule out the possibility that I’m dreaming. • If (1), I can’t know anything about the external world. • [So] I can’t know anything about the external world.