 We are very grateful to David Braun, Ray Drainville, Sally Haslanger, Chris Hookway, Jules Holroyd, and Nancy Tuana for their invaluable help with this entry. We would also like to thank Kathrin Gluer-Pagin for spotting some misidentified sentences in an earlier version of this entry, and Erik Tellgren for alerting us to Paul Gross’s response to Emily Martin. Special thanks are due to Mary Kate McGowan for her extremely helpful advice on the 2010 update to this entry, and to Ann Garry and Heidi Grasswick for their very useful comments on the 2017 update.