Descartes' Demon

Descartes' Demon is a philosophical thought experiment proposing that a powerful, possibly malicious, being—like an all-knowing demon—could manipulate our perceptions, making us believe in a physical world or truths that aren't real. It challenges the certainty of our knowledge, prompting questions about how we can truly know anything exists outside of our mind. Essentially, it underscores skepticism about sensory experience and invites us to consider whether doubt itself can be a foundation for knowledge.