Being a foundationalist, Descartes needs to destroy the foundations of
his beliefs so that in his Meditations he will be able to build upon new
foundations of undeniable and self evident truths. In order to do this Descartes
must first find a valid argument that will allow him to doubt his foundation
beliefs and in turn doubt what is considered to be reality. He begins by first
noting that one can not trust their own senses, because we can be deceived by
our sciences. An example of such would be if one looks at an optical illusion,
they are seeing something that is not really there, and therefore are being
deceived by their sense of sight. But this is not enough to justify doubting all
things, so Descartes offers a different approach, the Dream Argument.
The Dream Argument is essential in because it allows one to logically
question not only the senses but their surroundings and actions as well.
Although one can doubt that what they see or hear is not really as is perceived;
a person can not deny that they are for instance, standing, thinking about how
their senses are deceiving them, with their feet planted on the ground, in their
bedroom, feeling a little tired and so on. Only if one was, as Descartes writes,
'..insane, whose brains are impaired by such an unrelenting vapor of black
bile..' that they believe they are something other than what they are, would one
doubt reality, without an argument. The argument is as follows: If the
experience of a dream is indistinguishable between that dream and reality; and
there ...