Caledonian - the problem is, while we cannot show that consciousness exists in anything besides ourselves; we KNOW it at least exists inside ourselves. We know it more than we know that the earth exists, or that there are physical laws, etc. But when it comes to entities other than ourselves, it may as well be phlogiston; we can make ZERO predictions that would confirm or deny its existence. This is what makes it qualitatively different from any other phenomenon out there.