Remember the movie Indecent Proposal? Imagine the following scenario: A billionaire approaches a husband offering to pay him a $1,000,00 to sleep with his wife. The husband responds, "Let me think about that for a second." He thinks. And then says, "No."

What is your opinion of the husband, morally speaking?

If you are like most, your opinion is not very good. Why? Well, to use a phrase from the moral psychology literature, the husband had "one thought too many."

This "one thought too many" phenomena is called the mere contemplation effect. The mere contemplation effect is the observation that there are times when, to merely contemplate a decision, marks you as morally suspect. That is, a virtuous husband, in the scenario above, would have IMMEDIATELY rejected the offer. He wouldn't even need to "think about it."

Scenarios like this and the mere contemplation effect come from some fascinating research on taboo psychology, the psychology of the unthinkable. A great place to start in this literature is Philip Tetlock's research (start with: Tetlock, P.E., Kristel, O.V., Elson, S.B., 2000, The psychology of the unthinkable: Taboo trade-offs, forbidden base rates, and heretical counterfactuals. Journal of Personality and Social Psychology, 78, 853-870.)

I cite Tetlock's research to highlight that we expect moral judgments to be instinctive and reflexive. We really don't expect them to be the product of rational reflection. In fact, to even begin the process of reflection, in many cases, marks you as morally corrupt. This is the psychology of taboo.

If, for instance, someone has a taboo involving something like homosexuality (to take one example, since I discussed this taboo topic at length last week), when someone like me "merely contemplates" that homosexuality might not be a sin this marks me, for this person, as a dubious moral guide. In this. taboo psychology research is akin to the moral dumbfounding research in that it illustrates that our morality might be less rational than what we first might have guessed.

If you've been following me since my Moral Dumbfounding post (see "Eating your dog and having sex with chickens") I hope you are beginning to see the theme in my last few posts. Namely, that human moral judgment not simply the product of, say, "reading the Bible." Emotions and other mental biases all cook together in an elaborate stew to create our moral judgments. And taboo psychology is a part of that mix. We don't just read the Bible. We INTERACT with it in ways we are often unaware of. This is not to say that our moral decisions are irredeemably corrupted. But it is to say that most people are simply unaware of how little insight they have as to their own inner workings when they engage in morality debates.

And, as a psychologist, I'd like to shed some much needed light onto these dynamics.