In 1984, O'Brien claims that the party's philosophy is not solipsism. Why does he claim that? Was he telling the truth, and how does the party's philosophy actually differ from solipsism?
From chapter 3, section 3:
The belief that nothing exists outside your own mind - surely there must be some way of demonstrating that it was false. Had it not been exposed long ago as a fallacy? There was even a name for it, which he had forgotten...
"I told you, Winston," [O'Brien] said, "that metaphysics is not your strong point. The word you are trying to think of is solipsism. But you are mistaken. This is not solipsism. Collective solipsism, if you like. But that is a different thing; in fact, the opposite thing..."
Why does O'Brien claim that the party's philosophy is not only different than solipsism, but its exact opposite?