On average, your four people from 1500 would all be farmers or hunters and, apart from religion and customs, would probably understand one another’s lives. I’m not convinced we are coming to anything like a global consensus. While there is a sort of global pop culture and a common understanding of technology, individually we are more specialized than we have ever been. I would probably have an easier time talking to an aborigine than I would a hedge fund manager.

Beyond that, it’s an interesting conjecture. My personal experience with internet conversations is that they are still prone to all sorts of misunderstandings, particularly emotional ones – bereft as they are of facial expressions, body language, etc. :) The “feeling in the room” is something I cannot know that other people have. I infer what you feel based on your words, my prejudices, and my inductions. If other people really feel one another’s qualia I have been left out.

For clarity sake (because I think it’s necessary) I’m being playful here – not sarcastic. Thanks for the comment.