Whether the events of his recent memory -- the business with The Magnificence, the business of his hand being cut off and re-attached, the business of the committee, the delving into individual neuroses and collective identities of decay, and, at last, the business of him executing himself as the chairman of the committee -- have actually happened is beside the point. The point is that his hand hurts. No. The point is that he feels his hand hurting. Here is an irrefutable point: whether the pain is real or not is immaterial in terms of truth. What cannot be refuted is that he feels the pain.
There is wonderful comfort in this thought. His existence has been bewildering. He has been disoriented. He has not yet been able to figure out whether he has been hallucinating, or dreaming, or actually experiencing a strange physical reality. But it doesn't matter. He feels pain. This is a surety.