Third, they might be non-cognitivists, holding that moral "beliefs" aren't really beliefs at all. Rational intuition versus moral sense Some use the term "ethical intuitionism" in moral philosophy to refer to the general position that we have some non-inferential moral knowledge (see Sinnott-Armstrong, 2006a and 2006b)—that is, basic moral knowledge that is not inferred from or based on any proposition. However, it is important to distinguish between empiricist versus rationalist models of this. Some, thus, reserve the term "ethical intuitionism" for the rationalist model and the term "moral sense theory" for the empiricist model (see Sinnott-Armstrong, 2006b, pp. 184–186, especially fn. 4). However, the terminology is not ultimately important, so long as one keeps in mind the relevant differences between these two views. Generally speaking, rationalist ethical intuitionism models the acquisition of such non-inferential moral knowledge on a priori, non-empirical knowledge, such as knowledge of mathematical truths; whereas moral sense theory models the acquisition of such non-inferential moral knowledge on empirical knowledge, such as knowledge of the colors of objects (see moral sense theory). Rational intuition The rationalist version of ethical intuitionism models ethical intuitions on a priori, non-empirically-based intuitions of truths, such as basic truths of mathematics. Take for example the belief that two minus one is one. This piece of knowledge is often thought to be non-inferential in that it is not grounded in or justified by some other proposition or claim. Rather, one who understands the relevant concepts involved in the proposition that two minus one is one has what one might call an "intuition" of the truth of the proposition. One intuits the truth of the proposition, rather than inferring it. Likewise, the ethical intuitionist claims that basic moral truths—whether they are principles (such as don't kill people) or judgments (such as it is wrong to kill people)—are known without inference, and in particular they are known via one's rational intuition. Some rationalist ethical intuitionists characterize moral "intuitions" as a species of belief (for example, Audi, 2005, pp. 33–6) that are self-evident in that they are justified simply by virtue of one's understanding of the proposition believed. Others characterize "intuitions" as a distinct kind of mental state, in which something seems to one to be the case (whether one believes it or not) as a result of intellectual reflection. Michael Huemer (2005), for example, defines "intuition" as a sort of seeming: Reasoning sometimes changes how things