Contents
ACKNOWLEDGEMENTS xi
PREFACE xiii
CHAPTER 1
INTRODUCTION 1
Observation selection effects 1
A brief history of anthropic reasoning 5
Synopsis of this book 7
CHAPTER 2
FINE-TUNING IN COSMOLOGY 11
Does fine-tuning need explaining? 13
No “Inverse Gambler’s Fallacy” 16
Roger White and Phil Dowe’s analysis 18
Surprising vs. unsurprising improbable events 23
Modeling observation selection effects: the angel parable 32
Preliminary conclusions 39
CHAPTER 3
ANTHROPIC PRINCIPLES: THE MOTLEY FAMILY 43
The anthropic principle as expressing an observation
selection effect 43
Anthropic hodgepodge 46
Freak observers and why earlier formulations are inadequate 51
The Self-Sampling Assumption 57
CHAPTER 4
THOUGHT EXPERIMENTS SUPPORTING THE
SELF-SAMPLING ASSUMPTION 59
The Dungeon gedanken 59
Two thought experiments by John Leslie 62
The Incubator gedanken 64
The reference class problem 69
CHAPTER 5
THE SELF-SAMPLING ASSUMPTION IN SCIENCE 73
SSA in cosmology 73
SSA in thermodynamics 76
SSA in evolutionary biology 78
SSA in traffic analysis 82
SSA in quantum physics 84
Summary of the case for SSA 86
CHAPTER 6
THE DOOMSDAY ARGUMENT 89
Background 89
Doomsayer Gott 90
The incorrectness of Gott’s argument 92
Doomsayer Leslie 94
The premisses of DA, and the Old evidence problem 96
Leslie’s views on the reference class problem 104
Alternative conclusions of DA 107
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CHAPTER 7
INVALID OBJECTIONS AGAINST THE DOOMSDAY ARGUMENT 109
Doesn’t the Doomsday argument fail to
“target the truth”? 109
The “baby-paradox” 111
Isn’t a sample size of one too small? 115
Couldn’t a Cro-Magnon man have used the
Doomsday argument? 116
We can make the effect go away simply by considering
a larger hypothesis space 116
Aren’t we necessarily alive now? 118
Sliding reference of “soon” and “late”? 119
How could I have been a 16th century human? 119
Doesn’t your theory presuppose that what happens in causally
disconnected regions affects what happens here? 120
But we know so much more about ourselves than
our birth ranks! 120
The Self-Indication Assumption—
Is there safety in numbers? 122
CHAPTER 8
OBSERVER-RELATIVE CHANCES IN ANTHROPIC REASONING? 127
Leslie’s argument, and why it fails 127
Observer-relative chances: another go 130
Discussion: indexical facts—no conflict with physicalism 132
In conclusion 136
Appendix: the no-betting results 137
CHAPTER 9
PARADOXES OF THE SELF-SAMPLING ASSUMPTION 141
The Adam & Eve experiments 142
Analysis of Lazy Adam: predictions and counterfactuals 144
The UN++ gedanken: reasons and abilities 150
Quantum Joe: SSA and the Principal Principle 154
Upshot 156
Appendix: The Meta-Newcomb problem 157
Contents ix
CHAPTER 10
OBSERVATION SELECTION THEORY: A METHODOLOGY FOR
ANTHROPIC REASONING 159
Building blocks, theory constraints and desiderata 159
The outline of a solution 161
SSSA: Taking account of indexical information of observer-
moments 162
Reassessing Incubator 165
How the reference class may be observer-moment relative 168
Formalizing the theory: the Observation Equation 172
A quantum generalization of OE 174
Non-triviality of the reference class: why 0
must be rejected 175
A subjective factor in the choice of reference class? 181
CHAPTER 11
OBSERVATION SELECTION THEORY APPLIED 185
Cosmological theorizing: fine-tuning and freak observers 185
The freak-observer problem places only lax demands on
the reference class 193
The Sleeping Beauty problem: modeling imperfect recall 194
The case of no outsiders 195
The case with outsiders 196
Synthesis of the
1
⁄2- and the
1
⁄3-views 198
Observation selection theory applied to other scientific problems 198
Robustness of reference class and scientific solidity 202
Wrap-up 204
BIBLIOGRAPHY 207
INDEX 219
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