THE RELIABILITY OF SENSORY KNOWLEDGE Perspective on Descartes' Sixth Meditation
A fundamental question in philosophy is whether we can really know anything about the external world around us, including whether it exists. We can, after all, conceive that everything we think we see, hear, or feel around us is a hallucination or illusion, having no correspondence to any objective reality. Dreams seem real at the time, and people with mental disorders may hear voices that no one around them hears.
Descartes addresses this question in his Sixth Meditation. He starts by distinguishing between imagination and pure knowledge. We can not only conceive of the possibility of a triangle or pentagon, we can "see" it in our mind's eye, t