Methodical doubt is a systematic approach to questioning the certainty of knowledge and beliefs, primarily associated with the philosopher Renรฉ Descartes. This technique involves doubting all beliefs that can possibly be doubted, in order to establish a foundation of indubitable knowledge. By using this method, Descartes aimed to reach absolute certainty, which he ultimately found in the famous statement 'Cogito, ergo sum' or 'I think, therefore I am.'