 Dream skepticism has traditionally been the most famous and widely discussed philosophical problem raised by dreaming (see Williams 1978; Stroud 1984). In the Meditations, Descartes uses dreams to motivate skepticism about sensory-based beliefs about the external world and his own bodily existence. He notes that sensory experience can also lead us astray in commonplace sensory illusions such as seeing things as too big or small. But he does not think such cases justify general doubts about the reliability of sensory perception: by taking a closer look at an object seen under suboptimal conditions, we can easily avoid deception. By contrast, dreams suggest that even in a seemingly best-case scenario of sensory perception (Stroud 1984), deception is possible. Even the realistic experience of sitting dressed by the fire and looking at a piece of paper in one’s hands (Descartes 1641: I.5) is something that can, and according to Descartes often does, occur in a dream.