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Moral Dumbfounding

Moral dumbfounding is ‘the stubborn and puzzled maintenance of an [ethical] judgment without supporting reasons’ (Haidt, Bjorklund, & Murphy, 2000, p. 1). By the end of this section you should know what moral dumbfounding is and be familiar with some of the scientific research taken to establish that, and question whether, it occurs.

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Moral dumbfounding is ‘the stubborn and puzzled maintenance of a judgment without supporting reasons’ (Haidt et al., 2000, p. 1).

The most cited evidence for dumbfounding comes from some unpublished (!) research which is presented in the recording (Haidt et al., 2000). This research hinges on two contrasts:

  1. morally provocative but harmless events vs nonmorally provocative but harmless events; and
  2. morally provocative events that are harmless vs morally provocative scenarios involving harm

Examples of morally provocative but harmless events:

‘[Incest] depicts consensual incest between two adult siblings, and [...] [Cannibal] depicts a woman cooking and eating a piece of flesh from a human cadaver donated for research to the medical school pathology lab at which she works. These stories were ... were carefully written to be harmless’ (Haidt et al., 2000).

The other scenarios commonly used in studies of moral dumbfounding are Heinz and Trolley.

An Effect of Cognitive Load?

‘In Study 2 [which is not reported in the draft] we repeated the basic design while exposing half of the subjects to a cognitive load—an attention task that took up some of their conscious mental work space—and found that this load increased the level of moral dumbfounding without changing subjects’ judgments or their level of persuadability’ (Haidt & Bjorklund, 2008, p. 198).

Further evidence for an effect of cognitive load is provided by McHugh, McGann, Igou, & Kinsella (2023).[1]

Can We Rely on Haidt et al. (2000) as Evidence?

Before relying on any study we must check whether there are (i) successful or unsuccessful replications, ) (ii) similar studies with convergent or divergent results, and (iii) reviews or metaanalyses in which the study features (see Moral Intuitions and Emotions: Evaluating the Evidence).

Royzman, Kim, & Leeman (2015) claim to have unsuccessfully replicated the unpublished research on moral dumbfounding:

‘3 of [...] 14 individuals [without supporting reasons] disapproved of the siblings having sex and only 1 of 3 (1.9%) maintained his disapproval in the “stubborn and puzzled” manner’ (Royzman et al., 2015, p. 309).

They conclude that:

‘a definitionally pristine bout of MD is likely to be a extraordinarily rare find, one featuring a person who doggedly and decisively condemns the very same act that she has no prior normative reasons to dislike’ (Royzman et al., 2015, p. 311).

But your lecturer is unconvinced by this. They did, in fact, find one person who was dumbfounded even by their own criteria. Further, Haidt et al. (2000)’s method is to compare morally provocative events that are harmless with morally provocative scenarios involving harm.[2] Their prediction is that their should be significantly more dumbfounding in the former. Royzman et al. (2015) have not designed an experiment which tests this prediction.

McHugh, McGann, Igou, & Kinsella (2017) offers a successful replication.[3] These results were extended in McHugh, McGann, Igou, & Kinsella (2020) and McHugh et al. (2023).

McHugh, Zhang, Karnatak, Lamba, & Khokhlova (2023) investigated moral dumbfounding with participants drawn from three different regions: China, India and North Africa and the Middle East. They found evidence for moral dumbfounding in all cases, with variation in which dilemmas invoked most dumbfounding:

‘for both the Indian sample and the MENA sample, Trolley appeared to evoke the highest rates of dumbfounding, while for the Chinese sample, Cannibal evoked the highest rates of dumbfounding. In contrast for WEIRD samples, Incest tends to be the scenario that most reliably evokes dumbfounding (McHugh, Zhang, et al., 2023, p. 1056)

Do We Even Need a Study?

It seems quite easy to elicit moral dumbfounding in everyday life. This is something you could try for yourself.[4]

Appendix: Philosophical Perspectives

This section is not in the spoken lecture

Two recent discussions of dumbfounding are Guglielmo (2018) and Wylie (2021).

Ask a Question

Your question will normally be answered in the question session of the next lecture.

More information about asking questions.


Cannibal : ‘Jennifer works in a medical school pathology lab as a research assistant. The lab prepares human cadavers that are used to teach medical students about anatomy. The cadavers come from people who had donated their body for the general use of the researchers in the lab. The bodies are normally cremated, however, severed cuts may be disposed of at the discretion of lab researchers, One night Jennifer is leaving the lab when she sees a body that is going to be discarded the next day. Jennifer was a vegetarian, for moral reasons. She thought it was wrong to kill animals for food. But then, when she saw a body about to be cremated, she thought it was irrational to waste perfectly edible meat. So she cut off a piece of flesh, and took it home and cooked it. The person had died recently of a heart attack, and she cooked the meat thoroughly, so there was no risk of disease.’ (McHugh, Zhang, et al., 2023, p. supplementary materials; based on Haidt et al., 2000)
Heinz : ‘In Europe, a woman was near death from a very bad disease, a special kind of cancer. There was one drug that the doctors thought might save her. It was a form of radium for which a druggist was charging ten times what the drug cost him to make. The sick woman’s husband, Heinz, went to everyone he knew to borrow the money, but he could only get together about half of what it cost. He told the druggist that his wife was dying, and asked him to sell it cheaper or let him pay later. But the druggist said, “No, I discovered the drug and I’m going to make money from it.” So, Heinz got desperate and broke into the man’s store to steal the drug for his wife. The druggist had Heinz arrested and charged.’ (McHugh, Zhang, et al., 2023, p. supplementary materials; based on Haidt et al., 2000)
Incest : ‘Julie and Mark, who are brother and sister, are travelling together in France. They are both on summer vacation from college. One night they are staying alone in a cabin near the beach. They decide that it would be interesting and fun if they tried making love. At very least it would be a new experience for each of them. Julie was already taking birth control pills, but Mark uses a condom too, just to be safe. They both enjoy it, but they decide not to do it again. They keep that night as a special secret between them, which makes them feel even closer to each other’ (McHugh, Zhang, et al., 2023, p. supplementary materials; based on Haidt et al., 2000)
moral dumbfounding : ‘the stubborn and puzzled maintenance of an [ethical] judgment without supporting reasons’ (Haidt et al., 2000, p. 1). As McHugh et al. (2017) note, subsequent researchers have given different definitions of moral dumbfounding so that ‘there is [currently] no single, agreed definition of moral dumbfounding.’ I adopt the original authors’ definition, as should you unless there are good reasons to depart from it.
replicate an experiment : To replicate a experiment is to attempt to repeat it with the aim of reproducing the original findings. Where the original findings are not found, it is called a failed replication.
A replication can be more or less direct; that is, it may adhere very closely to the original experiment, or it may include varations in the stimuli, subjects and settings. Very indirect replications are sometimes called conceptual replications.
Trolley : A dilemma; also known as Switch. A runaway trolley is about to run over and kill five people. You can hit a switch that will divert the trolley onto a different set of tracks where it will kill only one. Is it okay to hit the switch?


Dwyer, S. (2009). Moral Dumbfounding and the Linguistic Analogy: Methodological Implications for the Study of Moral Judgment. Mind & Language, 24(3), 274–296.
Guglielmo, S. (2018). Unfounded dumbfounding: How harm and purity undermine evidence for moral dumbfounding. Cognition, 170, 334–337.
Haidt, J., & Bjorklund, F. (2008). Social intuitionists answer six questions about moral psychology. In W. Sinnott-Armstrong (Ed.), Moral psychology, Vol 2: The cognitive science of morality: Intuition and diversity (pp. 181–217). Cambridge, Mass: MIT press.
Haidt, J., Bjorklund, F., & Murphy, S. (2000). Moral dumbfounding: When intuition finds no reason. Unpublished manuscript, University of Virginia.
McHugh, C., McGann, M., Igou, E. R., & Kinsella, E. L. (2017). Searching for Moral Dumbfounding: Identifying Measurable Indicators of Moral Dumbfounding. Collabra: Psychology, 3(1), 23.
McHugh, C., McGann, M., Igou, E. R., & Kinsella, E. L. (2020). Reasons or rationalizations: The role of principles in the moral dumbfounding paradigm. Journal of Behavioral Decision Making, 33(3), 376–392.
McHugh, C., McGann, M., Igou, E. R., & Kinsella, E. L. (2023). Cognitive Load Can Reduce Reason-Giving in a Moral Dumbfounding Task. Collabra: Psychology, 9(1), 73818.
McHugh, C., Zhang, R., Karnatak, T., Lamba, N., & Khokhlova, O. (2023). Just wrong? Or just WEIRD? Investigating the prevalence of moral dumbfounding in non-Western samples. Memory & Cognition, 51(5), 1043–1060.
Royzman, E. B., Kim, K., & Leeman, R. F. (2015). The curious tale of julie and mark: Unraveling the moral dumbfounding effect. Judgment & Decision Making, 10(4).
Wylie, D. (2021). The limits of moral dumbfounding. Mind & Language, 36(4), 610–626.


  1. McHugh, McGann, et al. (2023) do make a strong case for the effect of cognitive load on reducing reasoning generally. But note that these researchers did not find evidence either way concerned effects of cognitive load in the Incest scenario. They speculate that this could be due to lack of statistical power. ↩︎

  2. Compare Haidt et al. (2000): ‘They made the fewest such declarations in Heinz, and they made significantly more such declarations in the Incest story.’ ↩︎

  3. Note that in McHugh et al. (2017), Study 1 is a bit different from the other studies. In Study 1, there is a robust distinction between the ’reasoning’ dilemmas (Heinz and Trolley) and the ‘intuition’ dilemmas (Incest and Cannibal). In Study 3a and 3b together there is weaker evidence for this distinction. But Studies 2+ were all online studies, and I am not persuaded that they actually worked (perhaps participants were simply rushing through the questions?). ↩︎

  4. Be careful; it turns out that some people react badly if you ask them about incest and eating their pets. ↩︎