The Doomsday argument purports to show that the risk of the human species going extinct soon has been systematically underestimated. This argument has something in common with controversial forms of reasoning in other areas, including: game theoretic problems with imperfect recall, the methodology of cosmology, the epistemology of indexical belief, and the debate over so-called fine-tuning arguments for the design hypothesis. The common denominator is a certain premiss: the Self-Sampling Assumption. We present two strands of argument in favor of this assumption. Through a series of thought experiments we then investigate some bizarre prima facie consequences - backward causation, psychic powers, and an apparent conflict with the Principal Principle. (Previous working titles of this paper: "Paradoxes of the Self-Sampling Assumption", "The Doomsday Argument: One Step Nearer the Edge")

This paper adopts the Self-Indication Assumption as a way out of the Doomsday argument and the Adam-and-Eve conundrums. The author chooses to bite the bullet with regard to the 'Presumptuous Philosopher' objection.

This paper replies to and criticizes the above paper by Olum, arguing against the Self-Indication Assumption.

Critical remarks on the doomsday argment. Basically, these authors make what I have called the Self-indication assumption (SIA) and show that it cancels the Doomsday argument. This idea seems to have occurred independently to several authors. I believe Dennis Dieks was first, although his original paper didn't explain it very clearly and did not include the calculation showing that the cancellation is exact. None of the proponents of the SIA has yet confronted main objections against this assumption, however.

The Argument is formally valid, but ineffective," writes the author. What he means is that one can adjust the prior probabilities so that the posterior come out normal. True, but those posterior would then have to be in accordance with the Self-Indication Assumption. I'd say that Dieks is a closet supporter of SIA, although he would vigorously deny that. Supporters of SIA have to confront the Presumptuous Philosopher thought experiment.

Criticisms of the doomsday argument. I think Robin is also committing himself to the Self-Indication Assumption.

Criticism of the doomsday argument based on the "disembodied souls approach" - the self indication assumption once again.

Replies to some of the arguments given for the Self-Indication Assumption (by e.g. Ken Olum - see paper above).

This paper attacks both Gott's and Leslie's versions of the Doomsday argument.

Abstract: In this paper, I present a solution to the Doomsday argument based on a third type of solution, by contrast to on the one hand, the Carter-Leslie view and on the other hand, the Eckhardt et al. analysis. The present line of thought is based on the fact that both aforementioned analyses are based on an inaccurate analogy. After discussing the imperfections of both models, I present then a two-sided model that fits more adequately with the human situation corresponding to DA and encapsulates both Carter-Leslie's and Eckhardt et al.'s models. I argue then that this new analogy also holds when one takes into account the issue of indeterminism and the reference class problem. This leads finally to a novel formulation of the argument that could well be more consensual than the original one.

In a recent Mind paper, Kevin Korb and Jonathan Oliver advanced five different objections against the Doomsday argument. I show that all these objections fail.

A book review of John Leslie's "End of the World" that contains a criticism of the Doomsday argument.

A few brief notes on the above article.

In a recent paper in Mind, Sowers tries to refute the Doomsday argument on grounds that true random sampling requires all possible samples to be equally probable the time when the sample is taken. Yet the Doomsday argument does not rely on true random sampling. It presupposes random sampling only in a metaphorical sense. After arguing that Sowers' critique fails, I outline my own view on the matter, which is that the Doomsday argument is inconclusive and that by developing a theory of observation selection effects one can show why that is so.

Another recent response to Sowers.

Tries to show that the Doomsday argument can be applied even when you don't know your birth rank, and that this disables the Presumptuous Philosopher objection against the Self-Indication Assumption. (I reject the view that our having originated from Earth (or whatever unspecified 'region' Monton picks) is a reason to favor T1, unless there is something special about this origin. Everybody find themselves originating from some planet or region, so if the argument worked, everybody would have a reason to favor T1, independely of any particular characteristic of their evidence.)

Critiques the above paper by Monton.

This paper criticizes Richard Gott's version of the Doomsday argument. Unfortunately the author seems to be unaware of the more sophisticated Carter-Leslie version, and my own "no outsider requirement". It is when the total number of observers vary between the hypotheses under consideration that strange (interesting!) things begin to happen. See my 'Mysteries' paper above.

I have suggested that one possible solution of the Boltzmann brain problem is that the universe is decaying at an astronomical rate, making it likely to decay within 20 billion years. A problem with this suggestion is that it seems to require unnatural fine tuning in the decay mechanism that would not be explained anthropically. Here it is pointed out that if a spacetime version of volume averaging were used in the cosmological measure problem, this would give anthropic support for an impending cosmic doomsday.