Note: The core intuition driving this argument is not original to me. It was suggested to me by [redacted] and has been discussed informally among [redacted]. Of course, any mistakes in the presentation and discussion of the argument in this paper are mine alone.
This paper considers the argument according to which, because we should regard it as a priori very unlikely that we are among the most important people who will ever exist, we should increase our confidence that the human species will not persist beyond the current historical era, which seems to represent a crucial juncture in human history and perhaps even the history of life on earth. The argument is a descendant of the Carter-Leslie Doomsday Argument, but I show that it does not inherit the crucial flaw in its immediate ancestor. Nonetheless, we are not forced to follow the argument where it leads if we instead significantly decrease our confidence that we can affect the long run future of humanity.
Out of everyone who will ever live, how important are you? You might not know how to go about answering this question. Exactly how important were people living in the past, on average, keeping in mind the power they will have wielded over the present age? What resources and challenges will people in the future face? How many future people will there be? These are tough questions.
Even if there isn’t much evidence by which to constrain your beliefs, that doesn’t give you license to think what you like. It seems sensible to regard it as a priori very unlikely that out of all the billions or even trillions of people who might exist over the course of human history, you are among the very most important. Surely only a narcissist would believe something like that about themselves without strong evidence.
The foregoing reasoning hopefully strikes you as intuitively correct. In this paper, I’ll present an apparently reasonable argument showing that the presumption that you are a priori very unlikely to be among the very most important people who will ever live should increase your confidence that the human species will be wiped out within the next few hundred years, so long as we are allowed to make a few plausible empirical assumptions about our current historical epoch. I call this argument Doomsday Redux (DR).
An informal presentation of the argument is given in section 2. In section 3, I highlight the commonalities between the argument and the infamous Carter-Leslie Doomsday Argument (DA) (Carter and McCrea 1983; Leslie 1998; compare Gott 1993, 1994). This allows me to offer a more formal presentation of DR’s key steps. Section 4 argues that DR doesn’t inherit the key flaw in DA; I argue that DR should be taken as a valid anthropic argument even though DA can be rejected. Section 5 addresses two concerns that might be raised about the argument in section 4. Section 6 considers whether we could reasonably revise our beliefs about our place in human history so as to avoid the gloomy implications of DR. I argue that this could be achieved by significantly decreasing our confidence in our ability to affect the long-run future of humanity.