1911 Encyclopædia Britannica/Solipsism

SOLIPSISM (Lat. solus, alone, ipse, self), a philosophical term, applied to an extreme form of subjective idealism which denies that the human mind has any valid ground for believing in the existence of anything but itself. “It may best be defined, perhaps, as the doctrine that all existence is experience, and that there is only one experient. The Solipsist thinks that he is the one!” (Schiller). It is presented as a solution of the problem of explaining the nature of our knowledge of the external world. We cannot know things-in-themselves: they exist for us only in our cognition of them, through the medium of sense-given data. In F. H. Bradley’s words (Appearance and Reality): “I cannot transcend experience, and experience is my experience. From this it follows that nothing beyond myself exists; for what is experience is its (the self’s) states.”

See Idealism; also F. C. S. Schiller, Mind, New Series (April 1909).