Solipsism (/ˈsɒlɨpsɪzəm/; from Latin solus, meaning alone, and ipse, meaning self) is the philosophical idea that only one's own mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure. The external world and other minds cannot be known, and might not exist outside the mind. As a metaphysical position, solipsism goes further to the conclusion that the world and other minds do not exist. As such it is the only epistemological position that, by its own postulate, is both irrefutable and yet indefensible in the same manner.
Contents
1 Varieties
1.1 Metaphysical solipsism
1.2 Epistemological solipsism
1.3 Methodological solipsism
2 Main points
3 History
3.1 Gorgias (of Leontini)
3.2 Descartes
3.3 Berkeley
4 Psychology and psychiatry
4.1 Solipsism syndrome
4.2 Infant solipsism
4.3 Consequences
4.4 Last surviving person
5 Relation to other ideas
5.1 Idealism and materialism
5.2 Cartesian dualism
5.3 Philosophy of Schopenhauer
5.4 Radical empiricism
5.5 Rationalism
5.6 Philosophical zombie
5.7 Falsifiability and testability
5.8 Minimalism
5.9 Samsara
5.10 Eastern philosophies
5.10.1 Hinduism
5.10.1.1 Advaita Vedanta
5.10.1.2 Samkhya and Yoga
5.10.2 Buddhism
Varieties
There are varying degrees of solipsism that parallel the varying degrees of serious skepticism.
Metaphysical solipsism
Metaphysical solipsism is the strongest variety of solipsism. Based on a philosophy of subjective idealism, metaphysical solipsists maintain that the self is the only existing reality and that all other reality, including the external world and other persons, are representations of that self, and have no independent existence. There are weaker versions of metaphysical solipsism, such as Caspar Hare's egocentric presentism (or perspectival realism), in which other people are conscious but their experiences are simply not present.
Epistemological solipsism
Epistemological solipsism is the variety of idealism according to which only the directly accessible mental contents of the solipsistic philosopher can be known. The existence of an external world is regarded as an unresolvable question rather than actually false.
Epistemological solipsists claim that realism requires the question: assuming that there is a universe that is independent of the agent's mind, the agent can only ever know of this universe through its senses, how is the existence of the independent universe to be scientifically studied? If a person sets up a camera to photograph the moon when they are not looking at it, then at best they determine that there is an image of the moon in the camera when they eventually look at it. Logically, this does not assure that the moon itself (or even the camera) existed at the time the photograph is supposed to have been taken. To establish that it is an image of an independent moon requires many other assumptions that amount to begging the question.
Methodological solipsism
Methodological solipsism may be a sort of weak agnostic (meaning missing knowledge) solipsism. It is a consequence of strict epistemological requirements for Knowledge (e.g. the requirement that knowledge must be certain). They still entertain the points that any induction is fallible and that we may be brains in vats. However there are those who say that even what we perceive as the brain is actually part of the external world, for it is only through our senses that we can see or feel the mind. There are thoughts, but that's all that's known for certain.
Importantly, they do not intend to conclude that the stronger forms of solipsism are actually true. Methodological solipsists simply emphasize that justifications of an external world must be founded on indisputable facts about their own consciousness. The Methodological solipsist believes that subjective impressions (Empiricism) or innate knowledge (Rationalism) are the sole possible or proper starting point for philosophica
