It's possible to give a person posthypnotic suggestion that number four does not exist, for example. When they try to count their fingers, hilarity ensues:
1,2,3,5,6,7,8,9,10,11. WTF! 11 figers, this is wrong. I try to count fingers in both of my hands separately and sum them together. 1,2,3,5,6 and 1,2,3,5,6. 6+6=12 WTF, now I have 12 fingers.
If math and logic were hallucinations, they would lead into contradictions.
You could just keep adding spatial dimensions until 12 fingers are predicted by the theory. Of course, everybody knows you have both 11 fingers and 12 fingers, depending on how the hand is observed.
If math and logic were hallucinations, they would lead into contradictions.