Cartesian doubt

Cartesian doubt, developed by philosopher René Descartes, is a method of questioning everything to establish what can be truly known. It involves doubting all beliefs that are not absolutely certain, including sensory perceptions and external reality, because they can be deceiving. The goal is to find a foundation of certainty; famously, Descartes concluded that while doubting everything, the very act of doubt proves the doubter’s existence — summarized in “I think, therefore I am.” This method helps distinguish what is undeniably true from what is uncertain or unreliable.