 Third, if a priori knowledge exists, what is its extent? Empiricists have argued that a priori knowledge is limited to the realm of the analytic, consisting of propositions true solely by virtue of our concepts, and so do not convey any information about the world. Propositions that convey genuine information about world are called synthetic. a priori knowledge of synthetic propositions, empiricists would say, is not possible. Rationalists deny this. They might appeal to a proposition such as “If a ball is green all over, then it doesn’t have black spots” as an example of a proposition that is both synthetic and yet knowable a priori (see Ichikawa and Jarvis 2009 and Malmgren 2011 for a discussion of the content of such a priori justified judgments; for literature on a priori knowledge, see BonJour 1998, BonJour in BonJour &amp; Devitt 2005 [2013]; Boghossian and Peacocke 2000; Casullo 2003; Jenkins 2008, 2014; and Devitt 2014).