Short answer: Descartes' doubt was like WWI - the doubt to end all doubt. Only by doubting everything could Descartes hope to find anything that was certain (even if the only certainty is that nothing else is certain!).
Descartes found it impossible to doubt his own existence. The reason for this was that he felt that thoughts had to come from himself.
That he is sentient ie that he thinks.
he believed if you can doubt it, it must not exist.
For Descartes, this was the fact that he existed as a thinker. He was perfectly sure he was thinking; and he was likewise convinced that to be thinking he had to exist as some kind of substance.
Short answer: Descartes' doubt was like WWI - the doubt to end all doubt. Only by doubting everything could Descartes hope to find anything that was certain (even if the only certainty is that nothing else is certain!).
Descartes found it impossible to doubt his own existence. The reason for this was that he felt that thoughts had to come from himself.
Descartes cannot doubt his own existence, as captured in his famous statement "Cogito, ergo sum" - "I think, therefore I am."
He can not doubt that he thinks, therefore he exists.
In Descartes' Meditations, doubt serves as a tool for philosophical inquiry by challenging and ultimately casting skepticism on the reliability of sense perceptions and beliefs. Through methodical doubt, Descartes aims to uncover indubitable truths and establish a foundation of certain knowledge upon which to build his philosophical system. Doubt, therefore, acts as a catalyst for Descartes' quest for certainty and the establishment of foundational principles in his philosophy.
René Descartes, a French philosopher, created the system of systematic doubt. In his work "Meditations on First Philosophy," Descartes employs the method of doubt to question all his beliefs in order to find a foundation of certainty in knowledge.
That he is sentient ie that he thinks.
Descartes hopes to find out what he can know for certain, without any doubt, about the world and nature.
Descartes' theory of knowledge was to doubt all things and accept as knowledge the things that could not be doubted
he believed if you can doubt it, it must not exist.
Descartes believed that doubt was a crucial tool in the search for truth. By subjecting all his beliefs to doubt, he aimed to find a foundation of knowledge that could not be doubted. This led him to his famous statement "Cogito, ergo sum" (I think, therefore I am), which served as the starting point for his philosophical system.
Descartes' radical doubt refers to his method of systematically doubting all beliefs and knowledge in order to establish a foundation of certainty upon which to build his philosophy. By doubting everything that can be doubted, Descartes aimed to arrive at indubitable truths that could serve as a solid basis for his philosophical system.