Sane or Crazy?
Whitman was completely lucid and [I]knew what he was doing...
Was Charles Whitman sane or insane? He had no problems of cognition but he was gripped by strange impulses. He was lucid and he knew what he was doing ...QUOTE]
Psychosis is not 24/7 thingie, Hadding. It is episodic. This means that someone can be "normal" one moment and "crazy" the next.
When a patient slips from a rational stage into a psychotic episode, then his cognition (as you call it) shuts down and he goes ape without even realizing it. This can go on for days. When he finally comes out of his bout of psychosis, he cannot explain the things he did when he went on his rampage.
Hence his letter complaining about "irrational thoughts." It is similar to sleepwalking, hypnosis, hallucinations and delusions.
My point is that it is involuntary, which makes him a victim. All the intelligence, education, expertise and wisdom in the world does not make you immune to psychosis, whether it is induced by hallucinations or delusions. The only thing that can save you from this condition is anti-psychotic medication or, if it is caused by a brain tumor, neuro surgical intervention.