 Perhaps most of all, any defenders of the Intuition/Deduction thesis owe us an account of what intuition is and how it provides warranted true beliefs about the external world. What is it to intuit a proposition and how does that act of intuition support a warranted belief? Their argument presents intuition and deduction as an explanation of assumed knowledge that can’t—they say—be explained by experience, but such an explanation by intuition and deduction requires that we have a clear understanding of intuition and how it supports warranted beliefs. Metaphorical characterizations of intuition as intellectual “grasping” or “seeing” are not enough, and if intuition is some form of intellectual “grasping,” it appears that all that is grasped is relations among our concepts, rather than facts about the external world, as the empiricists defenders of intuition and deduction argue. One current approach to the issue involves an appeal to Phenomenal Conservatism (Huemer 2001), the principle that if it seems to one as if something is the case, then one is prima facie justified in believing that it is so. Intuitions are then taken to be a particular sort of seeming or appearance: “[A]n intuition that p is a state of its seeming to one that p that is not dependent on inference from other beliefs and that results from thinking about p, as opposed to perceiving, remembering, or introspecting” (Huemer 2005, p. 102). Just as it can visually seem or appear to one as if there’s a tree outside the window, it can intellectually seem or appear to one as if nothing can be both entirely red and entirely green. This approach aims to demystify intuitions; they are but one more form of seeming-state along with ones we gain from sense perception, memory, and introspection. It does not, however, tell us all we need to know. Any intellectual faculty, whether it be sense perception, memory, introspection or intuition, provides us with warranted beliefs only if it is generally reliable. The reliability of sense perception stems from the causal connection between how external objects are and how we experience them. What accounts for the reliability of our intuitions regarding the external world? Is our intuition of a particular true proposition the outcome of some causal interaction between ourselves and some aspect of the world? What aspect? What is the nature of this causal interaction? That the number three is prime does not appear to cause anything, let alone our intuition that it is prime. As Michael Huemer (2005, p. 123) points out in mounting his own defense of moral intuitionism, “The challenge for the moral realist, then, is to explain how it would be anything more than chance if my moral beliefs were true, given that I do not interact with moral properties.”