Foundationalism and distinct. Geometrical truths are also certain and indubitable; Descartes thus attempted to find truths which were clear and distinct because they would be indubitably true and a suitable foundation for knowledge. His method was to question all of his beliefs until he reached something clear and distinct that was indubitably true. The result was his "cogito ergo sum" – 'I think therefore I am', or the belief that he was thinking – as his indubitable belief suitable as a foundation for knowledge. This resolved Descartes' problem of the Evil Demon – the possibility that he was being deceived by
Cogito, ergo sum As a critic of Cartesian subjectivity, Heidegger sought to ground human subjectivity in death as that certainty which individualizes and authenticates our being. As he wrote in 1927: "This certainty, that "I myself am in that I will die," is the basic certainty of Dasein itself. It is a genuine statement of Dasein, while "cogito sum" is only the semblance of such a statement. If such pointed formulations mean anything at all, then the appropriate statement pertaining to Dasein in its being would have to be "sum moribundus" [I am in dying], "moribundus" not as someone gravely ill or wounded,