• Jessi Berkelhammer  “From Reducibility to Extensionality: The two editions of Principia Mathematica”, September 26, 2003, (MS Thesis?)


1 The system of Principia Mathematica's first edition
1.1 Basic principles of the logical system
1.2 The theory of types
1.3 Identity
1.4 Classes
2 The axiom of reducibility and the second edition of Principia Mathematica
2.1 Justification in the first edition for the axiom of reducibility
2.2 Reaction to the first edition
2.3 Changes made for the second edition
3 Further critiques of Principia Mathematica
3.1 Ramsey’s views
3.2 Russell’s response to Ramsey
3.3 Other responses to the second edition
Concluding remarks