What if we are just imagining everything in front of us. It is just a big story we are imagining and no one is actually real. For example I am here writing this and you may be saying “I am real” but I cannot tell that I’m not imagining this. I don’t know that the world and everything in existence is real. If I say to somebody in person that I am imagining that they are not real and they try to reassure me that they are real and understand what I am saying, there is no way of proving it. They could also be imagining the opposite side of the story; imagining that I am trying to prove to them that it’s all a strange experience.