Abstract

You and I are highly unlikely to exist in a civilization that has produced only 70 billion people, yet we find ourselves in just such a civilization. Our circumstance, which seems difficult to explain, is easily accounted for if many other civilizations exist and if nearly all of these civilizations die out sooner than usually thought, i.e., before trillions of people are produced. Because the combination of and make our situation likely and alternatives do not, we should drastically increase our belief that and are true. These results follow immediately when considering a many worlds version of the ``Doomsday Argument'' and are immune to the main criticism of the original Doomsday Argument.