The only thing required is "proof beyond a reasonable doubt." Not ALL doubt, just 'reasonable' doubt.

Descartes developed the method of doubt, also known as Cartesian doubt, which involved systematically doubting everything that could be doubted in order to arrive at indubitable knowledge. This method was aimed at establishing a foundation of certain knowledge upon which to build his philosophical system.

The method of doubt is a philosophical approach introduced by René Descartes to challenge our beliefs and find certainty in knowledge. By systematically doubting everything that can be doubted, Descartes aimed to uncover truths that cannot be reasonably doubted, such as his own existence ("Cogito, ergo sum"). This method has influenced modern philosophy and epistemology.

Rene Descartes approached problem solving by using a method called systematic doubt, also known as Cartesian doubt. He sought to doubt everything that could be doubted in order to arrive at irrefutable truths. This method involved breaking down problems into smaller parts and building upon certain knowledge to arrive at clear and distinct conclusions.

Descartes' concept of systematic doubt involves doubting everything that can be doubted in order to arrive at indubitable truths. By doubting the reliability of the senses, memory, and even the existence of an external world, Descartes sought to establish a foundation of knowledge based on clear and distinct ideas that could not be doubted. This method of doubt is a key component of his philosophical method known as Cartesian skepticism.