Moral intuitionism is usually characterized as the thesis that we have non-inferential moral knowledge. Any epistemological theory that posits non-inferential knowledge is a form of foundationalism, so moral intuitionism is a form of foundationalism. The thesis is usually accompanied by a description of the faculty of moral intuition. Sometimes moral intuition is considered a faculty of judgment that produces non-inferentially justified/warranted moral beliefs, some of which are true. Another characterization of moral intuition is as a special faculty of moral perception, analogous to vision (how far that analogy can be pushed depends on who you ask). All of these ways of describing moral intuition have their respective strengths and weaknesses, which is a topic for another time. In this post, I’m going to present an argument against moral intuitionism that does not assume any robust account of the faculty of moral intuition. All that is assumed for the sake of this argument regarding intuitionism is that it is a form of foundationalism; whether it’s internalist or externalist is immaterial to the thrust of the argument.
Now for the argument: There appear to be good reasons to think that our moral beliefs are formed under less-than epistemically appropriate conditions. Moral belief formation is supposedly subject to various cognitive biases and emotional influences. These various psychological phenomena, compounded by facts such as massive moral disagreement among seemingly rational people present us with good reason to think that many of our moral beliefs are probably false, or at the very least, unjustified/unwarranted.
Assuming that there is good evidence of these cognitive biases and emotional influences coming out of psychology and cognitive science, the moral intuitionist is presented with a dilemma. She is presented with a defeater for her moral beliefs in the form of evidence of the unreliable conditions under which they are formed. Either she can defeat this defeater or she cannot. If she cannot defeat the defeater, then she does not have non-inferential moral knowledge, which means some form of moral skepticism is true. If she attempts to defeat the defeater, then she must provide good reasons to think that her moral beliefs are formed under conditions conducive to their reliability. Let’s say she succeeds at defeating the defeater, and has given good reasons to think her moral beliefs are reliably formed. She has now provided a justificatory basis for her moral beliefs that renders her moral justification inferential. So, she does not have non-inferentially justified/warranted moral beliefs, but rather her moral beliefs are inferentially justified. So, either moral skepticism is the case or moral justification is inferential.
The intuitionist appears to be backed into a corner. However, things aren’t as they seem; she has two ways to resist the dilemma. The first way to avoid the conclusion is by challenging the principle that the defeater defeater must come in the form of evidence of the reliability of moral belief formation. Perhaps the defeater defeater could be evidence that moral belief formation is not influenced by the cognitive biases and emotional influences mentioned above. Note that that evidence is not evidence for the reliability of moral belief formation, but merely evidence against the case for their unreliability; so, the intuitionist using this strategy isn’t committed to the no non-inferential moral knowledge horn of the dilemma.
The second way to avoid the dilemma is by allowing for epistemically overdetermined beliefs; such beliefs gain justification/warrant from non-inferential and inferential sources. The intuitionist can allow for a defeater defeater that generates inferentially justified/warranted moral beliefs, while also claiming that such a defeater defeater restored non-inferential justification/warrant as well.
One may wonder what part the internalism/externalism distinction plays in this discussion. The argument appears to be neutral about whether or not justification/warrant/knowledge is extended. Even if some sort of reliabilism is true, the alleged evidence from psychology and cognitive science presents a potential defeater to one’s moral beliefs. So, it really doesn’t matter if one adopts internalism or externalism about moral knowledge.
For some of the alleged evidence against moral intuitionism and various formulations of the argument presented above, see Walter Sinnott-Armstrong’s book Moral Skepticisms, and his papers, An Empirical Challenge to Moral Intuitionism, Framing Moral Intuitions, and Moral Intuitionism Meets Moral Psychology.
For a more developed response to Armstrong’s argument along the lines of the critiques I explored above, see Moral Intuitionism Defeated? by Nathan Ballantyne and Joshua Thurow.