Consciousness is literally the only thing which can't be an illusion, because it's through consciousness that illusions are perceived in the first place. Cogito

Consciousness is literally the only thing which can't be an illusion, because it's through consciousness that illusions are perceived in the first place. Cogito ergo sum; you can doubt what you are experiencing as much as you like, maybe it's a dream, maybe it's a simulation, maybe there's an evil demon deceiving you through magical means, but you can't doubt the fact that you are experiencing at all, even doubt itself is part of the experience.