Doomsday Argument

The Doomsday argument is a family of arguments about humanity’s likely survival. There are mainly two versions of the argument discussed in the literature, both of which appeal to a form of Copernican principle (or principle of typicality or mediocrity). A first version of the argument (endorsed by, e.g., John Leslie) dictates a probability shift in favor of theories that predict earlier end dates for our species assuming that we are a typical—rather than atypical—member of that group.

The other main version of the argument is sometimes referred to as the ‘delta-t argument,’ and it has provoked both outrage and genuine scientific interest. It claims to allow one to make a prediction about the total duration of any process of indefinite duration based only on the assumption that the moment of observation is randomly selected. A variant of this argument, which gives equivalent predictions, reasons in terms of one’s rank in a sequential process.