  One concern about all forms of moral intuitionism is the fact that people can continue to disagree about the moral facts when they appear to agree on the non-moral facts. If we all possess the same faculty of moral intuition, should such disagreement be possible at all? But the moral intuitionist can counter this objection in the way suggested earlier when we considered the argument against the possibility of moral knowledge based on disagreement. There are too many other factors that may explain disagreement without giving up the assumption that we share a faculty of moral intuition. Another concern is that we learn what is right and wrong initially from examples and advice of our elders. Isn’t this fact about moral development inconsistent with the idea that morals are based ultimately on a priori intuition? It appears not. We begin to learn mathematics in a similar way, using concrete examples and relying on authority. Then, as we develop understanding, we are eventually able to grasp relevant truths, such as that 2 + 2 = 4, in a way that is not dependent on the vagaries of experience. If we put two oranges in a hat and then add two more and subsequently find five there, we assume an extra one was there to begin with or that it is a trick hat or that the oranges can mysteriously reproduce themselves. We don’t doubt that 2 + 2 = 4. Similarly, it may be argued, once we grasp the wrongness of treating another person merely as a means, finding many examples of this treatment or many people who think the treatment is right won’t in the least alter, or even seem relevant to, our perception of its wrongness. (See, however, Sinnott-Armstrong 1988, and the reply by Shafer-Landau 1988.)