The philosophical position that only one's own mind can be known to exist; as an extreme form of idealism it is self-undermining as a shared theory, and more loosely, a criticism of arguments that treat one perspective as the only valid one.
Solipsism is the position that only one’s own mind is certain to exist, or, in the stronger form, that nothing exists outside it. The two claims differ and the difference matters. The epistemological version says one cannot establish, from within one’s own experience, that other minds or an external world exist; the metaphysical version asserts that they do not. Almost everyone who discusses solipsism holds the first as a problem to be answered rather than the second as a doctrine to be defended — it works as a limiting case, the destination an argument must avoid reaching. It belongs to modern European epistemology, where scepticism about the external world became a standing difficulty, and its sense shifts with the argument it is being used against.
Why this entry carries no source list. This lexicon cites an official primary source wherever one exists. For a concept used across several traditions at once, no such source exists: there is no body with authority over it, and a signed academic reference — the tier this lexicon would otherwise reach for — has no entry under this headword. Citing one school’s formulation would present a position as a definition. So the entry names the senses in play and the distinction between them, which is the part a reader can actually use.