Russell: The Journal of Bertrand Russell Studies

russell: the Journal of Bertrand Russell Studies n.s. 33 (summer 2013): 59–94 The Bertrand Russell Research Centre, McMaster U. issn 0036–01631; online 1913–8032 oeviews PRINCIPIA’S SECOND EDITION Russell Wahl English and Philosophy / Idaho State U. Pocatello, id 83209, usa wahlruss@isu.edu Bernard Linsky. The Evolution of Principia Mathematica: Bertrand Russell’s Manuscripts and Notes for the Second Edition. Cambridge: Cambridge U. P., 2011. Pp. vii, 407; 2 plates. isbn: 978-1-10700-327-9. £96; us$159. ussell and Whitehead’s Principia Mathematica was a pioneering work which was in many ways overtaken by the success of the new discipline it helped found. There is little doubt that Principia Mathematica was one of the most important works in the development of symbolic logic, as even Quine, one of the critics of the foundations proposed in it, said: “This is the book that has meant the most to me.”Yet few mathematicians or logicians follow the theory of types proposed in Principia as the foundation of mathematics , nor the logicist project of which it is a variant. While much of Principia ’s notation has been incorporated into modern formal logic and set theory , much of it also is dated and not easy for contemporary mathematicians and logicians to read. Among those who were dissatisfied with the philosophical foundations of the first edition were the authors themselves.1 During 1923 and 1924 Russell revised and updated Principia, and the second edition of the first volume appeared in 1925 with the other two volumes appearing in 1927. What resulted was a new edition with the philosophical underpinning modi- fied, but with the superstructure, that is, the resulting theorems of the three volumes, unchanged. Russell wrote a new Introduction and added three Appendices , but other than that made only minor changes.The new philosophy of logic had as its core idea a principle of extensionality which Russell expressed as the view that “functions of propositions are always truth-functions and a function can only occur in a proposition through its values” (PM2 1: ______ 1 Russell wrote the new material for the second edition, but it is clear from a letter to him byWhitehead on 24 May 1923, quoted by Linsky, that he, too, thought the foundational system needed tweaking: “I don’t think that ‘types’ are quite right” (p. 16). o= 60 Reviews xiv). It is interesting that at times Russell seems to have been hesitant about even endorsing this change.2 The second edition of Principia has not been well received; by and large it has either been ignored or scorned. Linsky cites especially negative remarks by Monk, but others have dismissed the second edition additions and it has generally been thought a failure since 1944, when Gödel pointed out an error in the Appendix B proof that mathematical induction can be “rectified” even without the axiom of reducibility. The Evolution of Principia Mathematica makes available to scholars Russell’s notes and manuscripts of the new material added to the second edition. Linsky also seeks to redress the indifference to the second edition, to set the record straight about several misunderstandings , and to give an account of the new material.The book he has produced will be very valuable to scholars of Russell and to anyone interested in the development of type theory and indeed of logic as a whole during this time. This is also a difficult book, both because the material can get quite technical at times and also because the new material included in the introduction to the second edition is somewhat sketchy, and there are philosophical and technical points about which Russell himself is less than clear. As a result there have been disagreements about how the second edition is best to be interpreted. Linsky recognizes that the interpretive issues are under-determined by the text and wants to stay relatively neutral with respect to the different alternatives about the various controversies. At times it can be difficult to keep the various positions straight.The difficulty lies with the material, and Linsky does a very good job of explaining the issues to the layman. The work is divided into...