John Protzko

The disgusting truth about moral decision making

Posted on | October 10, 2015 | No Comments

A foundation of morality rests on a weak…foundation   allowmyselftointroducemyself

Moral foundations theory (MFT) suggests what really underlies our decisions about the morality of behavior are five fundamental factors of our reasoning: awareness of Harm, Fairness, Ingroup/Outgroup thinking, Authority, and Purity. It is predicted that these basic human concerns are what govern our decisions about what is moral and what is not (in the absence of moral systems like religiion). Three of these moral foundations: awareness of harm, purity, and ingroup/outgroup thinking, have been shown to predict decisions about whether to sacrifice one person to save a number of others (Crone & Laham, 2015). Therefore, there is reason to believe there may be a causal connection between at least awareness of harm, purity, ingroup/outgroup thinking, and moral decision making.
Correlation, however, doesn’t equal causation.

To establish that these foundations truly cause different judgments in moral decision making, we should alter these foundations and see how they affect decisions. One line of research has long affected people’s beliefs about purity and disgust. When you make people feel disgusted, they think moral transgressions are worse. This line of research helps establish purity/disgust as a foundation of moral decision making.

Not everybody has been ale to replicate this finding, however. In fact, new research shows that there are many unpublished experimental failures. So many, in fact, that when you take them into account, there is no effect of disgust on moral judgments.

This challenges the idea that purity/disgust is causally relevant for moral decision making; meaning, it may not be a foundation at all.

This creates a problem. What further complicates the interpretation is that the authors of the meta-analysis offered a counter-response.

In short, they argued: “The (unmoderated) amplification effect is, at most, very small—so small, in fact, that no existing study should have been able to detect it. It disappears entirely when accounting for publication bias”


There are some ways out of this quagmire. We could say that eliciting disgust is not theoretically relevant for the purity domain of the MFT. Disgust research is often discussed in light of Haidt’s Social Intuition Theory of moral decision making. This would seem odd, but would allow both theories to move forward without one set of research affecting the other.

More importantly though, if the disgust/purity work is attempting to understand the same basic phenomena in social intuitionism and MFT, the problem of causality comes into play.

If the effects of disgust/purity are indeed moderated by personality characteristics, working for some people and not for others, then we cannot claim that inducing people to feel disgusted has any affect on moral decision making. It is, at best, a conditional causal claim. This would be hard to reconcile as a foundation of moral decision making.

While overall the meta-analysis did confirm that inducing people to feel disgust through taste or smell had an effect on moral judgments, the authors argued the effects may be small and biased to experimental setup.

Either way, it appears the result of disgust is conditional on personality characteristics. When it comes to whether purity/disgust is a foundation of moral decision making, it either is not, or may be for some people but not others.


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