 We are grateful to Adam Carter, Dennis Whitcomb, Miranda Fricker, and Jose Medina for feedback on a draft of this entry. Mark Alfano carried out some of the research leading to this publication while he was affiliated as Visitor at the School of Philosophy, Australian National University. John Turri’s research was supported by the Social Sciences and Humanities Research Council of Canada, the Ontario Ministry of Economic Development and Innovation, and the Canada Research Chairs program.