The Moral Psychology of Disgust

Nina Strohminger, Victor Kumar

• Publisher: Rowman & Littlefield International
• Year: 2018
• ISBN:
  9781786603005
• Edition: 1
• Topic: Filosofia
• Subtopic: Filosofia etica e morale

Does disgust guide moral behavior, or does it hamper it? Does disgust play a critical role in ordinary moral judgments, or almost no role at all? In this volume, experts in the field come together to explore fundamental questions about the role that disgust plays (and ought to play) in our moral lives. This book features twelve new essays, nestled comfortably at the intersection of psychology and philosophy. The Moral Psychology of Disgust brings together leading scholars—ethical theorists, cognitive scientists, developmental psychologists, legal scholars, cognitive neuroscientists, anthropologists—each answering questions that arise at the intersection of morality and disgust. The book introduces readers to the most pressing issues facing the field, and gives a perspective that is representative of the range of views and concerns that reflect the current research terrain. The book addresses three main themes: the origins of moral disgust, exploring the evolutionary function of disgust and its role in sustaining group dynamics; the psychological mechanisms underlying disgust responses and the way in which disgust influences reasoning about agency, violence, sex, and meaning; and the ethical challenges posed by disgust. The contributors explore whether we are justified in using disgust to form beliefs about right and wrong and how disgust sheds light on the very nature of morality.

Part I

The Science of Moral Disgust

Chapter 1

Moralized Disgust versus Disgusting Immorality

An Adaptationist Perspective

Joshua M. Tybur, Catherine Molho, and Daniel Balliet

We’ll open this chapter with a gambit frequently employed by disgust researchers during conference talks: disgust the audience to both grab their attention and ensure that they grasp the phenomenon at hand. So, clear your head, take a deep breath, and imagine standing in a crowded bus and yawning at the precise time that a stranger sneezes, spewing mucus and saliva into your open mouth. Further imagine biting into a sandwich and, after feeling a “crunch” between your teeth, looking down to half of a rat’s tail ensconced between the slices of bread, with the other half semi-chewed in your mouth. And finally, imagine that, while riding a roller coaster, the person sitting next to you experiences motion sickness and vomits on your chest. Hopefully we’ve aroused some disgust in you at this point, and we’ve made you think of the types of things that spark this feeling.

Now try to explain why you would feel disgust in these situations. If you avoid appealing to the types of circular definitions that even some psychologists find irresistible (e.g., “because it’s gross” or “because it makes me feel dirty”—for a discussion, see Tybur et al. 2013), you’ll probably arrive at some explanation grounded in your knowledge of the germ theory of disease. Relative to most of the other objects we come into contact with on a daily basis, saliva launched from someone else’s mouth, vermin that (literally) spread the plague, and vomit are each likely to contain infectious microbes. And disgust seems tailored to neutralizing contact with such things. The experience is associated with a facial expression that reduces the surface area of the eyes that could be exposed to pathogens and decreases air flow through the nose (Susskind et al. 2008); it motivates a desire to avoid physical contact (Roseman et al. 1994)—exactly the path through which microscopic, infectious predators (but not large predators with claws and fangs) threaten humans; and it shapes learning in a way specialized for avoiding those things likely to house microbes (Tybur et al. 2016). In sum, in combination with the types of things that elicit disgust, the effects of disgust imply that it is functionally specialized for a specific task: avoiding pathogens. This type of specialization is the hallmark of an adaptation (Williams 1966/2008).

Some instances of disgust do not seem to fit within a pathogen-avoidance account, though. To illustrate (and, again, hopefully evoke disgust), imagine sharing a passionate, open-mouthed kiss with your sibling (or, if you don’t have one, feel free to substitute a parent). Naturally, others’ saliva can transmit pathogens. But open-mouthed kissing with an attractive, genetically unrelated individual—an act with similar pathogen risk to kissing a sibling—elicits a positive reaction rather than disgust. One need not dig too deep into the evolutionary biology literature to realize that sexual contact with genetic relatives carries costs distinct from infectious disease, though: close kin are more likely to share deleterious recessive alleles, which, when inherited from both parents, seriously impair an individual’s survival (Charlesworth and Charlesworth 1999). Further, the prospect of sex with a sibling is more disgusting for individuals who perceive a greater probability of genetic relation with their sibling (Lieberman, Tooby, and Cosmides 2007). Again, the fit between form and function suggests that sexual disgust is an adaptation for avoiding sex with low compatibility or quality reproductive partners.

Still, other instances of disgust do not seem to motivate the avoidance of pathogens or sexual partners. Consider what many felt when hearing Donald Trump lecherously brag about his “grab them by the pussy” sexual tactics, or about his encounter with a married woman in which he “moved on her like a bitch.” Or, for an apolitical example, consider the reaction that many had when Minnesota dentist Walter Palmer paid $50,000 to hunt and kill Cecil, a beloved lion and tourist attraction in a Zimbabwean national park. Such events often evoke disgust expressed via both language and nonverbal behavior (Chapman and Anderson 2013). In contrast with pathogen and sexual disgust, the functions of moral disgust (if any exist) are opaque. Indeed, the literature is full of conflicting accounts of moral disgust: some researchers describe it as a “metaphor” (Royzman and Kurzban 2011); others describe it as merely the “lay meaning” of disgust, used by the (wo)man on the street to convey anger, as opposed to the “theoretical meaning” that is of interest to psychologists (Nabi, 2002); others argue that it functions to protect the social order (Rozin, Haidt, and McCauley 2008); and still others argue that it motivates avoidance of free riders (Curtis and Biran 2001).

These inconsistencies in accounts of moral disgust are partially rooted in the fact that researchers disagree on the types of events that elicit the emotion. Some perspectives suggest that moral disgust is elicited by only a subset of behaviors referred to as “purity” or “divinity” violations (e.g., incest) (Koleva et al. 2012; Rozin et al. 1999). Other perspectives suggest that moral disgust is elicited by a wider array of behaviors—perhaps by any behavior that can be morally condemned (Chapman and Anderson 2013; Hutcherson and Gross 2011). And, as implied above, others suggest that “moral disgust” refers to an emotion no more than “green with envy” refers to a color (Nabi 2002)—that is, moral disgust is a quirk of language that does not reflect an emotional state distinct from anger.

This variety of perspectives on moral disgust can seem dizzying, especially when compared with the relative consensus on pathogen and sexual disgust. Here, we explore two factors that have contributed to this state of the literature (for similar treatments, see Landy and Goodwin 2015; Pizarro, Inbar, and Helion 2011; Tybur et al. 2013). On the one hand, researchers have used the single term “moral disgust” to refer to two distinct phenomena—what we label “moralized disgust” versus “disgusting immorality.” On the other hand, researchers have underutilized the evolutionary approach that has been so useful in understanding pathogen and sexual disgust. Here, we make use of this evolutionary approach to distinguish between moralized disgust and disgusting immorality.

Approaching Moral Disgust from an Adaptationist Perspective

The social sciences have been gradually evolutionized since the sociobiological revolution of the 1970s (Kenrick 2006). However, widespread adoption of evolutionary perspectives has been impeded by two issues. First, explanations derived from the perspective often conflict with intuitive folk psychology (Kurzban and Aktipis 2007). Second, evolutionary perspectives have been erroneously seen as supporting a right-wing political agenda, which liberal academics object to (Tybur, Miller, and Gangestad 2007). Even so, we are unaware of any critiques derived from these issues being launched at disgust researchers who use an evolutionary perspective. Instead, the highest-impact perspective on disgust (Rozin, Haidt, and McCauley 2008) explicitly proposes that pathogen disgust is an adaptation for avoiding infectious microbes, as have other widely cited theoretical works on the topic (e.g., Oaten, Stevenson, and Case 2011; Tybur et al. 2013). The fact that (a) pathogens clearly have impeded human survival and reproduction in the ancestral past, (b) things that elicit disgust often contain pathogens, and (c) the behaviors associated with disgust seem tailored for neutralizing pathogens renders this use of an evolutionary perspective relatively uncontroversial. Additionally, this use of an evolutionary perspective rarely raises the hackles of readers in the same way that studying sex differences does; whereas the latter can be perceived as justifying social inequalities (Tybur et al. 2007), the former has few social or political implications.

Nevertheless, some aspects of Rozin and colleagues’ (2008) same popular perspective sharply depart from adaptationism. The proposed “animal nature” aspect of disgust serves as a key example. Drawing from anthropologist Ernest Becker’s (1973) proposal that people are in a constant struggle against the recognition of their own mortality—and a putatively debilitating anxiety that would result from such a reminder—Rozin and colleagues suggest that many instances of disgust function to quell existential anxieties. Sex, corpses, poor hygiene, and open wounds purportedly elicit disgust because they remind people that they are animals, and, like animals, they will eventually die. Indeed, Rozin and colleagues argue that “anything that reminds us that we are animals elicits disgust” (p. 761), and disgust experienced toward these stimuli putatively “protect the body and soul” (p. 764). Several observations critically challenge this perspective (for summaries, see Royzman and Sabini 2001 and Tybur et al. 2013). For example, observing non-human animals engaging in myriad behaviors that humans also engage in (e.g., a chimpanzee eating, a dog sleeping, a cat sneezing) could increase the salience of similarities between human and non-human animals, but these behaviors elicit neither disgust nor apparent existential anxieties (Kollareth and Russell 2016). Further, no evidence suggests that disgust experienced toward corpses, wounds, or sex reduces existential anxieties. Most critically, the animal nature account posits that disgust functions to reduce an internally generated sensation rather than to motivate fitness-enhancing behaviors (i.e., roughly, behaviors that, relative to alternatives, increase survival and reproduction). In other words, the proposed function is entirely dedicated to reducing unpleasant sensations, which natural selection is blind to. Indeed, evolution shapes unpleasant sensations (e.g., pain, fear, anxiety) as motivators for behavior; unpleasant sensations do not shape the evolution of other palliative traits. Hence, our approach to understanding moral disgust will depart from the approach underlying the animal reminder perspective; instead of considering potential effects of moral disgust on hedonic experience (e.g., reductions of dissonance or anxiety), it will only consider behavioral consequences of moral disgust.

This focus on behavioral consequences can circumvent another shortcoming of multiple accounts of disgust: a reliance upon tautological definitions. For example, Darwin (1872/1965) described disgust as elicited by “something revolting.” Given that “revolting” is more or less synonymous with “disgusting,” this description does little to advance our understanding of disgust. Rozin and colleagues (2008) similarly argue that disgust is elicited by objects that possess a “sense of offensiveness” (p. 759)—that is, a sense of disgustingness—and that moral disgust is elicited by acts that are “sleazy”—that is, by acts that are disgusting. By forcing researchers to consider the fitness-relevant consequences of disgust elicitors, adaptationist perspectives sidestep the pitfall of tautology often seen in this area.

Taking an adaptationist approach does not commit a researcher to the claim that all traits are adaptations (Tooby and Cosmides 1992). As pointed out by Steven Jay Gould and Richard Lewontin (1979), two bulwarks against what they saw as promiscuous adaptationism, many traits are byproducts of other traits that were favored by selection. For example, rather than being shaped by natural selection due to some fitness-enriching effect, the belly button is the byproduct of the umbilical cord, which was shaped by selection (Buss et al. 1998). Of course, some traits that are not themselves adaptations can be used for different beneficial effects than those they evolved for (Gould and Vrba 1982). The belly button could be used to anchor a navel ring, which might enhance social status or physical attractiveness. Importantly, evidence that a trait is a byproduct can only follow from generating, testing, and rejecting adaptationist hypotheses (Andrews, Gangestad, and Matthews 2001). Because the belly button is the inevitable outcome of having an umbilical cord, and the putative beneficial effect is culturally specific (and very recent to the Western world), we can reject the hypothesis that the belly button is an adaptation rather than a byproduct. Rejecting such hypotheses is more difficult—but not impossible—for psychological traits, including moral disgust. The benefits of identifying adaptations are great, though; understanding what something is for can elucidate how it works. And, ultimately, generating and testing adaptationist hypotheses can yield beneficial information, even if doing so does not clearly adjudicate between adaptation and byproduct interpretations. In the spirit of these benefits (and the other benefits mentioned above), we first describe the potentially advantageous effects of condemning third parties who engage in pathogen disgust-eliciting and sexual disgust-eliciting behaviors.

Moralized Disgust

Haidt (2001) begins his seminal paper on the social intuitionist model of moral judgment with a description of Mark and Julie, fictional siblings who, on a whim, decide to have sex. According to Haidt, most people who hear the story morally condemn Mark and Julie, and this condemnation is based upon “a quick flash of revulsion” indicating “that something is wrong” (p. 814). Reactions to this story putatively reveal that moral judgments are shaped by emotional intuitions rather than (only) considerations of harm done by the acts (though see Royzman, Kim, and Leeman 2015, for a critical reinterpretation of this finding). That is, most people experience disgust when thinking about committing incest themselves, and this disgust results in moral condemnation of others engaging in this same act. The same could be said for a variety of other acts that, on the one hand, have some disgust-eliciting content and, on the other hand, are also morally condemned. Examples include bestiality, cannibalism, homosexuality, pedophilia, and consuming tabooed foods. Based on the cross-cultural prevalence of moral condemnation of such behaviors, researchers have proposed that disgust-motivated “purity” morals form one pillar of moral cognition (Haidt 2012; Koleva et al. 2012). Here, disgust is the reason why a behavior is considered to be morally wrong. Indeed, the purity subscale of the popular Moral Foundations Questionnaire (Graham et al. 2011) is partially defined by the item “Whether or not someone did something disgusting.”

This perspective has inspired research programs testing whether experimentally manipulating experienced disgust increases moral condemnation. Several findings in this area suggest that moral condemnation can be increased by making participants experience disgust (e.g., manipulated via primes, such as a disgust-eliciting odor, taste, or image) before judging another’s behavior (e.g., Horberg et al. 2009; Schnall et al. 2008; Wheatly and Haidt 2001). However, a recent meta-analysis (Landy and Goodwin 2015) of this literature and a highly powered replication of one of these priming studies (Johnson et al. 2016) indicate that transient feelings of disgust do not increase moral condemnation. The lack of an amplification effect does not preclude the existence of disgust-based moral condemnation, though. Instead, it demonstrates that disgust experiences unrelated to a potentially condemnable act (e.g., a disgust-eliciting smell) have no effect on moral condemnation. Phrased in the computation language sometimes used to understand morality (e.g., DeScioli and Kurzban 2013; Mikhail 2008), disgust might only serve as an input to moral cognition if the disgust is elicited by the to-be-condemned behavior.

Why would people morally condemn pathogenic or sexually disgusting acts? Considering the costs and benefits of condemning third parties’ behaviors can help answer this question. On the benefits side, condemnation can signal attributes that are valued in interaction partners (Miller 2007). For example, condemning others’ selfishness or sexual promiscuity might communicate prosociality or a monogamous sexual orientation, respectively. It can also signal intentions to others, and hence allow third parties to coordinate their moral condemnation in a manner that attenuates costly moral conflicts (DeScioli 2016). And it can help shape the types of behaviors that are per...

Table of contents

• Introduction: Disgust: A Cross-Pollination
• Part I: The Science of Moral Disgust
• Part II: The Philosophy of Moral Disgust
• Index
• About the Contributors