In Descartes' meditations, Descartes begins what Bernard Williams has called the project of 'pure enquiry' to discover an indubitable premise or foundation to base his knowledge on, by subjecting everything to a kind of scepticism now known as Cartesian doubt. This is known as foundationalism, where a philosopher basis all epistemological knowledge on an indubitable premise.
             Within meditation one Descartes subjects all of his beliefs regarding sensory data and even existence to the strongest and most hyperbolic of doubts. He invokes the notion of the all powerful, malign demon who could be deceiving him regarding sensory experience and even his understanding of the simplest mathematical and logical truths in order to attain an indubitable premise that is epistemologically formidable. In meditation one Descartes has three areas of doubt, doubt of his own existence, doubt of the existence of God, and doubt of the existence of the external world. Descartes' knowledge of these three areas are subjected to three types of scepticism the first where he believes that his senses are being deceived 'these senses played me false, and it is prudent never to trust entirely those who have once deceived us'. The second of the forms of scepticism revolves around whether Descartes is dreaming or not 'I see so clearly that there are no conclusive signs by means of !
             which one can distinguish between being awake and being asleep'. The aforementioned malign demon was Descartes third method of doubt as he realised God would not deceive him.
             Descartes' search for an underlying foundational premise ends when he realises he exists, at least when he thinks he exists 'doubtless, then, that I exist and, let him deceive me as he may, he can never bring it about that I am nothing, so long as I shall be conscious that I am something. So that it must, in fine, be maintained, all things being maturely ...