   What then is it for a proposition to be self-evident? Locke says that a self-evident proposition is one that “carries its own light and evidence with it, and needs no other proof: he that understands the terms, assents to it for its own sake” (1969, 139). Price tells us that a self-evident proposition is immediate, and needs no further proof, and goes on to say that self-evident propositions need only be understood to gain assent 1758/1969, 187). Ross writes, a self-evident proposition is “evident without any need of proof, or of evidence beyond itself” (1930/2002, 29), and Broad describes self-evident propositions as being “such that a rational being of sufficient insight and intelligence could see it to be true by merely inspecting it and reflecting on its terms and their mode of combination” (1936, 102–3). These passages may have led to the standard understanding of a self-evident proposition that one finds in Shafer-Landau (2003, 247) and Audi (2001, 603; see also Audi 2008, 478). Audi, for instance, writes that self evident propositions are “truths such that (a) adequately understanding them is sufficient justification for believing them …, and (b) believing them on the basis of adequately understanding them entails knowing them” (2008, 478).