In some ways I think it is the emotions that give the air of reality to something. Knowing something intellectually is very different to knowing it on an emotional level. And alters often hold opposing viewpoints / realities... so it is really hard for one alter who loves a person to understand the reality of another alter who was abused by that same person. Their emotional realities are completely different. Incompatible even. It takes a long, long time to work through such extreme emotional conflict to find a middle ground.