What role does doubt play in descartes meditation?

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.