Solipsism is the philosophical belief that the only entity that can be conclusively known to exist is oneself, more specifically, one's mind. It is important to note that solipsism does not deny the existence of the universe as we perceive it; it simply states that it cannot be proven to exist, since we cannot prove that the evidence given by our senses is not an illusion.
Within this general definition of solipsism, there are three subtypes:
- Metaphysical solipsism: The idea that one's mind is the only reality, and that the "external" world is merely a projection and representation of one's mind.
- Epistemological solipsism: The idea that the existence of the mind is the only thing that can be conclusively known, and all things external to the mind are unknowable.
- Methodological solipsism: The idea that since the self is the only thing that can be conclusively known, then in order to be valid, philosophical belief must be grounded in the individual self and its states.