Ever wonder why it’s so hard to have a productive political discussion with people you radically disagree with, or why people’s opinions on controversial issues so rarely change?  There’s a new study out that finds that “the brain takes a mere quarter of a second to react to statements that contradict or challenge our ethical belief system. That nearly instantaneous neural response colors the way the rest of the sentence — and thus, the rest of the thought — is interpreted.”  If somebody begins to talk about something in way that you disagree with, it your brain almost instantaneously raises warning flags that cause you to regard the rest of what you hear with skepticism.
Of course, none of this is new.  Jonathan Haidt wrote this paper on moral intuitionism back in 2000.  Although the majority of the moral philosophical canon is grounded on a model of human moral judgment as a process of reasoning, a lot of empirical research (including this study) indicates that human moral judgment primarily consists of ex post justifications of prior, emotionally determined responses.

The fact that rational arguments generally do not determine people’s morality is bad news for the prospects of human moral progress.  However, it’s a mistake to think that just because we are naturally moral intuitionists, we must necessarily be moral intuitionists (that’s the naturalistic fallacy).  In fact, according to the Haidt paper linked above, there is one subset of humans that is especially good at overcoming natural tendencies to arrive at rational moral judgments: philosophers!