Solipsism... is sometimes spoken of as the philosophical term for insanity. It certainly seems to stand for metaphysics run mad, or, in politer language, for subjective idealism carried to extremes. The solipsist claims to be the sole inhabitant of the universe, and all manifestations to the contrary are merely subjective states of his own. As with so many other mentally unbalanced persons, his cosmos is all ego.
The argument in favor of Solispsism, put most simply, is as follows: "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."The argument derives its strength, in part, from false theory, but to a greater extent perhaps, from thoughtless obscurity.
Bertrand Russell remarked that he was cured of solipsism for life by receiving a letter from a woman saying, 'I'm so glad you think there may be something in solipsism. I wish there were more of us.'
What is hell? Hell is oneself. And nothing to escape to. One is always alone.
All the inclinations together (which can be reduced to a tolerable system, in which case their satisfaction is called happiness) constitutes self-regard, (solipsismus). This is either the self-love that consists in an excessive fondness for oneself (philautia), or satisfaction with oneself (arrogantia). The former is called particularly selfishness; the latter self-conceit.
Solipsism has no real ground to stand on and the pragmatist is the very last in the line of those who may be accused of even seeming to have taken, or to have tried to take, his stand there.
If I felt reckless or strong enough to shoulder the responsibility, I might not object to a solipsism that made me the all by emphasising the inevitable relation of experience to an experient; the trouble comes when other experients claim a monopoly of this relation in the face of conflicting claims, and propose to reduce me to incidents in their cosmic nightmare.
[Solipsism is] the doctrine that all existence is experience, and that there is only one experient. The Solipsist thinks that he is the one. ...that the 'absolute idealist' is a Solispsist need only be barely stated. ...He is a Solipsist because he believes that the Absolute is the sole experiment, and that he is himself the incarnate Absolute."