Martin Cohen is a teacher and writer specializing in philosophy, ethics and education, with a special interest in computing. His books include101 Philosophy Problems (2nd edn., 2001),Political Philosophy (2001) and101 Ethical Dilemmas (2003). He has been editor ofThe Philosopher since 1995.

List of Figures vii

Forward! viii

Introduction: Deep Thought a brief history of thought experiments 1

The AZ

A is for Alice and Astronomers Arguing about Acceleration 15

B is for Bernards Body-Exchange Machine 18

C is for the Catholic Cannibal 20

D is for Maxwells Demon 25

E is for Evolution (and an Embarrassing Problem with it) 28

F is for the Forms Lost Forever to the Prisoners of the Cave 30

G is for Galileos Gravitational Balls 33

H is for Humes Shades 37

I is for the Identity of Indiscernibles 41

J is for Henri Poincaré and Alternative Geometries 45

K is for the Kritik and Kants Kind of Thought Experiments 48

L is for Lucretius Spear 52

M is for Machs Motionless Chain 55

N is for Newtons Bucket 58

O is for Olbers Paradox 62

P is for Parfits Person 65

Q is for the Questions Raised by Thought Experiments Quotidiennes 67

R is for the Rule-Ruled Room 70

S is for Salvatius Ship, Sailing along its own Space-Time Line 74

T is for the Time-Travelling Twins 78

U is for the Universe, and Einsteins Attempts to Understand it 81

V is for the Vexed Case of the Violinist 84

W is for Wittgensteins Beetle 87

X is for Xenophanes and Thinking by Examples 90

Y is for Counterfactuals and a Backwards Approach to

History 93

Z is for Zeno and the Mysteries of Infinity 97

Notes for Experimenters

How to Experiment 103

Notes and Cuttings 117

Whos Who of Experimenting 126

Acknowledgements 131

Index 132