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anthropic-principle.com

An annotated preprint archive

INDEX

THE DOOMSDAY ARGUMENT (The Doomsday argument is a controversial application of anthropic reasoning that tries to show that we have systematically overestimated the life expectancy of the human species. Apart from the intrinsic interest of this result if it were valid (which I think it is not - see chapter 10 of my book), the argument also provides an important test case for proposed ways of reasoning about observation selection effects.)

The Doomsday Argument, Adam & Eve, UN++, and Quantum Joe: Nick Bostrom Recommended

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. [Penultimate draft of paper published in Synthese (2001), vol. 127, issue 3, pp. 359-387. Previous working titles of this paper: "Paradoxes of the Self-Sampling Assumption", "The Doomsday Argument: One Step Nearer the Edge"][pdf]

The Doomsday Argument and the Number of Possible Observers: Ken Olum Recommended

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. [Philosophical Quarterly (2002), Vol. 52, No. 207, pp. 164-184]

The Doomsday argument and the Self-Indication Assumption: Reply to Olum: Nick Bostrom and Milan M. Cirkovic Recommended New

This paper replies to and criticizes the above paper by Olum, arguing against the Self-Indication Assumption. [Penultimate version of paper in Philosophical Quarterly, (2003), Vol. 53, No. 210, pp. 83-91][pdf].

The Doomsday Argument without Knowledge of Birth Rank: Bradely Monton New

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.) [pdf-format].

No Doomsday argument Without Knowledge of Birth Rank: A Defense of Bostrom: Darren Bradley New

Critiques the above paper by Monton.

A Third Route to the Doomsday Argument: Paul Franceschi New

"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." [Preprint, (2003)] [pdf-format].

The Mysteries of Self-Locating Belief and Anthropic Reasoning: Nick Bostrom Recommended New

Summary of the difficulties that a theory of observation selection effects faces and a sketch of a solution. [Harvard Review of Philosophy, Vol. 11, pp., 59-74 (2003).] [pdf]

Beyond the Doomsday Argument: Reply to Sowers and Further Remarks: Nick Bostrom New

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. [pdf-format]

Is Many Likelier than Few? A Critical Assessment of the Self-Indication Assumption: Milan M. Cirkovic

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

Predicting Future Duration from Present Age: A Critical Assessment: Carlton Caves

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 "Mystique" paper above.

The Probability of Doom: Dennis Dieks

"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 (see e.g. the "Adam & Eve"-paper above).

La Belle au bois dormant, la fin du monde et les extraterrestres: Jean-Paul Delahaye New

L’analyse de plusieurs énigmes troublantes suggère la notion d’anamorphose probabiliste et fournit la solution du paradoxe de l’Apocalypse. Pour la Science (2003), No. 309, Juillet. [pdf-format]

The Doomsday Argument is Alive and Kicking: Nick Bostrom

In a recent Mind-paper, Kevin Korb and Jonathan Oliver advanced five different objections against the Doomsday argument. Here I show that all these objections fail.[Penultimate draft of a paper published in Mind (1999), Vol. 108, No.431, pp. 539-50.]

Apocalypse Just Not Now: Mark Greenberg

A book review of John Leslie's "End of the World" that contains a criticism of the Doomsday argument. [London Review of Books, Vol. 21, No. 13 (1999)]

A critical look at Mark Greenberg's attempted refutation of the Doomsday argument: Nick Bostrom

A few brief notes on the above article

An Empirical Critique of Two Versions of the Doomsday Argument - Gott’s Line and Leslie’s Wedge: Elliott Sober

This paper attacks both Gott's and Leslie's versions of the Doomsday argument. [Forthcoming in Synthese.] [pdf]

Observer-relative chances in anthropic reasoning?: Nick Bostrom

John Leslie argues that anthropic reasoning implies the existence of paradoxical observer-relative chances. I argue that he is wrong on this point. [Penultimate draft of a paper in Erkenntnis (2000), Vol. 52, pp. 93-108.]

Too soon for doom gloom?: Tomas Kopf, Pavel Krtous, and Don N. Page

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 Doomsday argument and Hempel's problem: Paul Franceschi

Criticizes the Doomsday argument, or at least proposes a reference class that would reduce the probability shift. Also a crash course in botany. [Paul has kindly provided this translation of a paper that he originally published in French in the Canadian Journal of Philosophy (1999), Vol. 24, pp. 139-56.]

A Bayesian Analysis of the Doomsday Argument: Jonathan Oliver, Kevin Korb

Calculations and critical comments

Critiquing the Doomsday Argument: Robin Hanson

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

No One Knows the Date of the Hour: An Unorthodox Application of Rev. Bayes' Theorem: Paul Bartha, Christopher Hitchcock

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

The Doomsday Argument: a Literature Review: Nick Bostrom

A survey to bring you up to speed. [I'd recommend the more recent version contained in my dissertation instead.]

Analysing the Doomsday Paradox with the Minimum of Probability Theory: Jason Grossman and Peter Lipton

This work-in-progress criticizes the doomsday argument on grounds that it doesn't provide an argument for what the authors call the "separability condition". This, however, is only true of some expositions. The separability condition seems to follow from the Self-Sampling Assumption, for which arguments are given e.g. here. [pdf]

Investigations into the Doomsday argument: Nick Bostrom

My first paper on the topic (1996-1997). Various themes that are elaborated in later papers were anticipated here.

Distributional Assumptions and Generating Mechanisms: a Critical Note on the Doomsday Argument: Loren A. King

Argues that information about the mechanisms that generate the sequence of human lives is relevant and weakens the doomsday argument

ANTHROPIC APPLICATIONS IN COSMOLOGY (Readers who are interested in applications in cosmology may also want to search some of the other sections here, which are of direct or indirect relevance to the underlying methodology, and also the physics preprint archive at http://xxx.lanl.gov, which contains many papers on the related physics.)

Self-Locating Belief in Big Worlds: Cosmology's Missing Link to Observation: Nick Bostrom Recommended New

This paper argues that contemporary cosmological theories give probability one to every possible human observation being made. This creates a puzzle: if a theory predicts that every possible observation is in fact made, then how do we test it? What could possibly count as negative evidence? How can we arbitrate between rivalling cosmological theories on empirical grounds? - Only by taking observation selection effects into account, using something like the Self-Sampling Assumption! [pdf; MS-Word format] Journal of Philosophy, 2002, Vol. 99, No. 12.

Philosophical Implications of Inflationary Cosmology: Joshua Knobe, Ken D. Olum, Alexander Vilenkin New

Recent developments in cosmology indicate that every history having a nonzero probability is realized in infinitely many distinct regions of spacetime. Thus, it appears that the universe contains infinitely many civilizations exactly like our own, as well as infinitely many civilizations that differ from our own in any way permitted by physical laws. We explore the implications of this conclusion for ethical theory and for the doomsday argument. In the infinite universe, we find that the doomsday argument applies only to effects which change the average lifetime of all civilizations, and not those which affect our civilization alone.

The Cold Big-Bang Cosmology as a Counter-example to Several Anthropic Arguments: Anthony Aguirre

Examines ways in which some simultaneous changes of several apparently fine-tuned parameters might cancel out the life-destroying effects that altering only one parameter would have, thus potentially weakening the degree of fine-tuning that we have in our universe.

Open Inflation Without False Vacua: S.W. Hawking, Neil Turok

Shows that with the Hartle-Hawking `no boundary' proposal and a minimal anthropic condition, inflation can easily generate an open universe

Fine-Tuning and Multiple Universes: Roger White

White argues, taking up and refining an earlier idea of Ian Hacking's, that the anthropic explanation that seeks to explain why we see a fine-tuned universe by postulating a the existence of a multiverse fails because we must look at the most specific version of the evidence we have, and that is not just that "Some universe is fine-tuned." but that "This universe is fine-tuned." - this latter fact not being one that is made any more probable by the existence of lots of other universes according to White. I criticize his argument in the paper below. [pdf-format preprint of paper published in Noûs (2000). 34:2, pp. 260-276]

Fine-Tuning Arguments in Cosmology: Nick Bostrom

Investigates whether fine-tuning is something that needs explaining, and if so, whether a multiverse theory could provide a satisfactory explanation. [pdf-format; this is chapter 2 of my book]

The density parameter and the Anthropic Principle: Jaume Garriga, Takahiro Tanaka, Alexander Vilenkin

Predicts the value of the density parameter Omega within the framework of inflation theory using the anthropic principle

Open universes, inflation, and the anthropic principle: Alexander Vilenkin

Argues that the anthropic principle is essential to derive predictions from models that seek to reconcile inflation theory with being in an open universe

Defining Civilization utilizing Anthropic Reasoning: Kevin A. Pimbblet

Abstract: "We utilize anthropic reasoning to demonstrate that we are typical observers of our reference class under a self-sampling assumption by investigating the definition of what a civilization is. With reference to the conflict between such reasoning and the observational lack of extra-terrestrial intelligent life, we conclude that a part of our theoretical understanding of the Universe will be at fault." [Note: This paper contains some inaccuracies; e.g. my view is not that all observers who will ever have lived should be included in one's reference class. - N. B.] [Forthcoming in The Observatory]

ANTHROPIC APPLICATIONS IN EVOLUTIONARY BIOLOGY

Must Early Life be Easy? The Rhythm of Major Evolutionary Transitions: Robin Hanson Recommended

Uses anthropic considerations to estimate the number of hard steps in human evolution, following an ingenious argument by Brandon Carter

Is the Strong Anthropic Principle too weak?: A. Feoli, S. Lampone

Discusses Carter's formula for the probability of the evolution of intelligent life

THE SIMULATION ARGUMENT (This started with my paper "Are you living in a computer simulation?", which argued that the simulation hypothesis (meaning that we are living in a simulation in a computer created by some advanced civilization) should be given substantial probability. More precisely, it argued that at least one of three possibilities obtain; see below. This paper appeared in Philosophical Quarterly in 2003, but a preprint has been available since 2001.)

Are You Living In a Computer Simulation?: Nick Bostrom Recommended New

This paper argues that at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a "posthuman" stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the transhumanist dogma that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation. A number of other consequences of this result are also discussed. [Philosophical Quarterly, 2003, Vol. 53, No. 211, pp. 243-255] [html][pdf]

How to Live In a Simulation: Robin Hanson

If you might be living in a simulation then all else equal you should care less about others, live more for today, make your world look more likely to become rich, expect to and try more to participate in pivotal events, be more entertaining and praiseworthy, and keep the famous people around you happier and more interested in you. [Journal of Evolution and Technology (2001). Vol. 7.]

Innocence Lost: Simulation Scenarios: Prospects and Consequences: Barry Dainton New

Abstract: "Those who believe suitably programmed computers could enjoy conscious experience of the sort we enjoy must accept the possibility that their own experience is being generated as part of a computerized simulation. It would be a mistake to dismiss this is just one more radical sceptical possibility: for as Bostrom has recently noted, if advances in computer technology were to continue at close to present rates, there would be a strong probability that we are each living in a computer simulation. The first part of this paper is devoted to broadening the scope of the argument: even if computers cannot sustain consciousness (as many dualists and materialists believe), there may still be a strong likelihood that we are living simulated lives. The implications of this result are the focus of the second part of the paper. The topics discussed include: the Doomsday argument, scepticism, the different modes of virtual life, transcendental idealism, the Problem of Evil, and simulation ethics." [pdf]

Living in a Simulated Universe. John D. Barrow New

Barrow argues that we might expect to see occasional glitches and small drifts in the supposed constants and laws of Nature over time if we are living in a simulation. (My opinion is that simulators would probably be typically be able to run the simulation in such a way that its inhabitants would not notice anything abnormal.) (2003, May), Draft. [pdf]

GENERAL THEORY OF ANTHROPIC PRINCIPLES AND OBSEVATION SELECTION EFFECTS [some of the papers listed under the Doomsday argument are also relevant here]

Anthropic Bias: Observation Selection Effects in Science and Philosophy: Nick Bostrom Recommended

This book (five sample chapters are available here) explores how to reason when you suspect that your evidence is biased by observation selection effects. An explanation of what observation selection effects are has to await chapter 1. Suffice it to say here that the topic is intellectually fun, difficult, and important. We will be discussing many interesting applications: philosophical thought experiments and paradoxes aside, we will use our results to address several juicy bits of contemporary science: cosmology (how many universes are there?), evolution theory (how improbable was the evolution of intelligent life on our planet?), the problem of time's arrow (can it be given a thermodynamic explanation?), game theoretic problems with imperfect recall (how to model them?), traffic analysis (why is the "next lane" faster?) and a lot more - the sort of stuff that intellectually active people like to think about… (Routledge, New York, April 2002)

Observational-selection effects and probability: Nick Bostrom

Doctoral dissertation (an early precursor to and now superceded by the book). It presents a theory that models observational selection effects in a Bayesian framework and resolves a range of conundrums related to anthropic reasoning. It shows a way of avoiding the Doomsday argument while at the same time catering to legitimate methodological needs in cosmological theorizing and other sciences.

Mindless Sensationalism: Don Page Recommended

Presents an interpretation of quantum mechanics and discusses its relation to a consciousness in the framework of observation selection effects

Anthropic coincidences: Al Shroeder

Lists and explains fifteen anthropic coincidences, ways in which the fundamental constants appear to be fine-tuned to allow life

Cosmology and Theology: John Leslie Recommended

Entry for the Stanford Encyclopedia of Philosophy

A review of anthropic reasoning: Nick Bostrom

An overview of the literature up to September 1998. [The more recent material in my book is recommended instead of this.]

THE ANTHROPIC PRINCIPLE VS. DESIGN ARGUMENTS

Fine-Tuning Arguments in Cosmology: Nick Bostrom

Investigates whether fine-tuning is something that needs explaining, and if so, whether a multiverse theory could provide a satisfactory explanation. [pdf-format; this is chapter 2 of my book]

There Is No Adequate Definition of 'Fine-tuned for Life': Neil A. Manson

Argues that no appropriate definition of 'fine-tuned for life' has been given that supports an inference to something extra-cosmic. [Inquiry, Vol. 43, No. 3, pp. 341-351 (2000)]

Barrow and Tipler on the Anthropic Principle vs. Divine Design: William Lane Craig

Craig argues that the AP does not refute the design argument

Is the Weak Anthropic Principle Compatible With Divine Design?: A Response to Craig: Kyle Kelly

Criticizes Craig's paper

The Anthropic Coincidences, Evil and the Disconfirmation of Theism: Quentin Smith

Attacks Swinburn's attempt to argue for God's existence on the basis of the anthropic coincidence

The Design Argument: Elliott Sober

A part of it deals with the argument from fine-tuning. [From Blackwell Guide to Philosophy of Religion] [pdf]

ANTHROPIC REASONING AND TIME'S ARROW. (Ludwig Boltzmann attempted (on the basis of an idea credited to his assistant, Dr. Schuetz) to give an anthropic explanation of time's arrow and of why entropy is increasing. I have argued in chapter 4 of my book that his explanation does not work.)

The Thermodynamical Arrow of Time: Reinterpreting the Boltzmann-Schuetz Argument: Milan M. Cirkovic. Foundations of Physics (2003). Vol. 33, No. 3, pp. 467-490. New

Anthropic Fluctuations vs. Weak Anthropic Principle: Milan M. Cirkovic

Examines the Boltzmann-Schuetz explanation. Foundations of Science (2002). Vol. 7. pp. 453-463. [pdf]

THE SLEEPING BEAUTY PROBLEM AND GAME THEORY APPLICATIONS. (My view is that these contributions would have benefitted from checking whether proposed solutions make sense when considered in lights of requirements from other domains, e.g. cosmological theorizing.

Some "Sleeping Beauty" postings: (ed.) Nick Wedd

Nick Wedd has performed a public service by collecting selected postings on the newsgroup rec.puzzles on the Sleeping Beauty problem, by himself and others, and editing them into an easy-to-read webpage.

Self-Locating Belief and the Sleeping Beauty Problem: Adam Elga

Elga presents an argument for one view on the SB-problem. (David Lewis has a reply to this paper in Analysis, July, 2001.) [Analysis (2000). 60(2): 143-147.]

The Absent-Minded Driver Paradox: Synthesis and Responses: Michele Piccione and Ariel Rubinstein Recommended

The authors summarize and reply to various responses to one of their earlier papers (also published in the same volume - G&EB vol, 20 is wholly devoted the Absent-Minded Drivers Paradox). [Games and Economic Behavior 20 (1997), 121-130] [pdf]

On the Interpretation of Decision Problems with Imperfect Recall: Michele Piccione and Ariel Rubinstein

Discusses the Absent-Minded Driver Problem [Games and Economic Behavior (1997). Vol. 20, pp. 3-24] [pdf]

A Note on Imperfect Recall: Ken Binmore

Offers some general comments on game theoretic modeling on imperfect recall problem and analyzes an infinitely-repeated version of the Absent-Minded Driver. [pdf]

THE FERMI PARADOX (New section)

Geo-engineering Gone Awry: A New Partial Solution of Fermi’s Paradox: Milan Cirkovic New

Compares two out of the many explanations that have been proposed. [pdf]

HISTORY OF ANTHROPIC REASONING

Ancient Origins of a Modern Anthropic Cosmological Argument: Milan Cirkovic New

If our bit of the world has existed for a past eternity, why don't we find traces of past civilizations and their achievements "ingrafted in eternal monuments of glory", Lucretius once wondered, and concluded that some kind of singular state had existed a finite time ago. This paper argues that ancient thinkers anticipated some themes of contemporary anthropic arguments in cosmology. [Astronomical and Astrophysical Transactions, Vol. 22, No. 6, pp. 879-886, December 2003.

On the First Anthropic Argument in Astrobiology: Milan Cirkovic New

We consider the little-known anthropic argument of Fontenelle dealing with the nature of cometary orbits, given a year before the publication of Newton’s Principia. This is particularly interesting in view of the rapid development of the recently resurgent theories of cometary catastrophism and their role in the modern astrobiological debates, for instance in the “rare Earth” hypothesis of Ward and Brownlee. [pdf]

MISCELLANEOUS

The Many-Worlds FAQ: Mike Price

Frequently asked questions about the many-worlds interpretation of quantum mechanics. A classic usenet document. One frequently asked question it omits is: "What has Mike been doing after he wrote this document (his previous active Internet presence having ended abruptly)?" Answer: Playing chess.

Cars In the Next Lane Really Do Go Faster: Nick Bostrom

Applying anthropic reasoning to traffic planning [PLUS (2001), Vol. 17]

Is "the theory of everything" merely the ultimate ensemble theory? and Does the universe in fact contain almost no information? Max Tegmark Recommended

In these two papers, Tegmark develops the idea that all mathematically self-consistent structures are physically real (a form of all-possible-worlds-actually-exists theory). What makes Tegmark's approach highly interesting is that he takes the first steps towards making such a theory quantitative and capable of generating empirically testable predictions. "Further funding required", however, before this project can achieve its promise.

Is the universe really so simple: Milan Cirkovic

Discusses Tegmark's ideas.

Indefinite Information Processing in Ever-Expanding Universes: John Barrow and Sigbjorn Hervik New

Argues that generic anisotropic universes arbitrarily close to the open Friedmann universe allow information processing to continue into the infinite future if there is no cosmological constant or stable gravitationally repulsive stress, and the spatial topology is non-compact. An infinite amount of information can be processed by “civilisations” who harness the temperature gradients created by gravitational tidal energy. These gradients are driven by the gravitational waves that sustain the expansion shear and three-curvature anisotropy. [Phys.Lett. B566 (2003) 1-7] [pdf]

Time without end: physics and biology in an open universe: Freeman J. Dyson

Argues that life can survive for an infinite time in an open universe. Groundbreaking at its time because it addressed the question of the long-term prospects of life in the universe and suggested that life's action must be taken into account when predicting the long-term development of the universe. A bit dated now.

Introduction to the Omega Point Theory: Frank Tipler

Argues that an infinite number of computations can be done in the last stages of the Big Crunch. Unfortunately for Tipler's theory, it now looks like there won't be a Big Crunch (because the universe will keep on expanding forever). So Tipler's attempt to derive something like Christian theology from physics has failed. At least it had the virtue of being falsifiable. (Tipler admits that if recent evidence that the universe is open is confirmed, then his theory is wrong; however, he still thinks that better measurements over the next few years of the cosmic red shift and the cosmological constant will show that the present empirical conclusions were premature.)

Life, The Universe, and Nothing: Life and Death in an Ever-Expanding Universe: Lawrence M. Krauss and Glenn D. Starkman

A more up-to-date examination of infinite information processing in the universe than both Dyson's and Tipler's. Pessimistic conclusion. However, see also the following paper:

Cosmological Constant and the Final Anthropic Hypothesis: Milan M. Cirkovic, Nick Bostrom

Examines the implications of recent evidence for a cosmological constant for the prospects of indefinite survival of intelligent information processing in the multiverse. [Astrophysics and Space Science, Vol. 279, No. 4, pp. 675-687]

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