 Linsky (2011) provides a discussion, both of the Appendix itself and of the suggestion that by 1925 Russell may have been out of touch with recent developments in the quickly changing field of mathematical logic. He also addresses the suggestion, made by some commentators, that Whitehead may have been opposed to the revisions, or at least indifferent to them, concluding that both charges are likely without foundation. (Whitehead’s own comments, published in 1926 in Mind, shed little light on the issue.)