 Furthermore, one way of implementing this approach leads to absurd consequences. The Doomsday Argument, for example, claims to reach a striking conclusion about the future of the human species without any empirical input (see, e.g., Leslie 1992; Gott 1993; Bostrom 2002). Suppose that we are “typical” humans, in the sense of having a birth rank that is randomly selected among the collection of all humans that have ever lived. We should then expect that there are nearly as many humans before and after us in overall birth rank. For this to be true, given current rates of population growth, there must be a catastrophic drop in the human population (“Doomsday”) in the near future. The challenge to advocates of indifference applied to observers is to articulate principles that avoid such consequences, while still solving (alleged) problems such as that of freak observers.