This book 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...

Summary of the difficulties that a theory of observation selection effects faces and a sketch of a solution.

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.

Abstract: Anthropic reasoning often begins with the premise that we should expect to find ourselves typical among all intelligent observers. However, in the infinite universe predicted by inflation, there are some civilizations which have spread across their galaxies and contain huge numbers of individuals. Unless the proportion of such large civilizations is unreasonably tiny, most observers belong to them. Thus anthropic reasoning predicts that we should find ourselves in such a large civilization, while in fact we do not. There must be an important flaw in our understanding of the structure of the universe and the range of development of civilizations, or in the process of anthropic reasoning.

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!

A concise introduction to observation selection theory and its applications to cosmology, with some discussion of the challenges that arise in the case of infinite spacetimes containing an infinite number of observers.

A classic anthropic argument in cosmology.

The anthropic principle, which asserts that what we can expect to observe must be restricted by the conditions necessary for our presence as observers, is discussed in relation to several large number coincidences. An illustration is given of the use of the 'strong' anthropic principle, which states that the Universe must be such as to admit the creation of observers within it at some stage, to predict a priori the weakness of the gravitational coupling constant.

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

"Anthropic shadow" is an observation selection effect that prevent observers from observing certain kinds of catastrophes in their recent geological and evolutionary past. We risk underestimating the risk of catastrophe types that lie in this shadow.

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.

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.

Elga presents an argument for the 'Thirder' view on the Sleeping Beauty problem.

Lewis responds to Elga's paper, defending the 'Halfer' viewpoint.

Discusses Dutch book arguments in relation to the Sleeping Beauty problem, with particular attention to Christopher Hitchcock's recent paper on this in Synthese.

The Absent-Minded Driver predates the Sleeping Beauty puzzle and shares some of its puzzling characteristics. 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 tothe Absent-Minded Drivers Paradox).

Hugh Everett III's 1955 Phd dissertation, presenting the original 'no-collapse' interpretation of quantum mechanics.

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

This is the "full-strength version" of Tegmark's 'Theory of Everything', which develops the idea that all mathematically self-consistent structures are physically real (a form of all-possible-worlds-actually-exist theory). Tegmark conjectures that all and only computable and decidable (in Gdel's sense) structures exist, which alleviates the cosmological measure problem and helps explain why our physical laws appear so simple. 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.