I've written before about the psycho-immune function of disgust and the generalization of disgust reactions to the moral realm. The immunological function of disgust certainly makes intuitive sense when you consider some commonplace objects of disgust, for example, bodily fluids and excretions, rotting and decaying things, certain stinky things, glistening, leaky, blobulous innards or perhaps clams before the first time you tried them. We are turned off by things that appear to have a higher probability of spreading dangerous contagions.
But as is the case with the rest of the immune system, the psycho-immune system is imperfect, sometimes missing genuine threats and sometimes signaling threat where no danger exists. Moreover, our psycho-immune reactions are suppressible by sexual excitement and modifiable by culture and experience. Clean up kiddy vomit for a period of time, as this big brother did, and it's no big deal.
The generalization of disgust reactions to the moral realm is of special interest to me because an understanding of moral purity codes as psychosocial-immunity systems can help us understand both our conflicted minds and the conflicted culture[s] of the modern world, especially in the area of sexuality, with its associated guilt-ridden impulses and wishes.
One problem we face as moderns is that we have methods to more realistically assess danger and protect ourselves from contamination while our ancient psychosocial immune systems are often at odds with a modern understanding of disease and contagion. Add to that, we know that people differ from one to the next in their disgust sensitivity. And while far from the only determinant, there is some evidence that disgust sensitivity may provide a nudge to our political identifications. Specifically, conservatives as a group have a higher (average) level of disgust sensitivity when compared with liberals. My own speculation is that lower disgust sensitivity might also describe a subset of libertarians. To be clear, I'm talking nudges, averages and generalities. There are surely other factors that predispose and shape political identities and moral inclinations, but it's interesting to ponder the possibility that on some issues we are having an underlying argument about what is and what is not disgusting, driven in part by individual variation in disgust sensitivity.
Purifying, cleansing and sacralizing rituals also make sense when we understand purity codes as extensions of a modifiable, imperfect psycho-immune system. Examples that leap to mind are immersion in water as a symbolic cleansing agent in a ritual to wash away sin, and matrimony as a ritual that turns dirty acts into sacred acts. I deliberately used the word dirty here to underscore the common association between dirty (contaminated) and sinful or bad.
Here are a few of my previous posts on this subject: Sacralizing the Objects of Disgust (or that's gross, let's do it); Sexual Dysfunction and Disgust; Disgust and Homophobia. The first of those posts emphasized how complicated things get when the archaic psycho-immune system conflicts with the reproductive imperative.
I may return to this discussion because I have more to say about it, but in the meantime, I've lifted a couple of quotes from something Andrew Sullivan posted today. Actually, it was Sullivan's post that prompted my post.
First, from Janet Bicknell:
According to [author of Don’t Look, Don’t Touch, Don’t Eat: The Science of Revulsion [Valerie] Curtis, moral disgust evolved out of physical disgust and originally served the same purpose of infection avoidance. We need to interact with others, but we don’t want to risk contamination with their bodily fluids. So we work out a system of manners and rules so that we can interact without contamination. This is the beginning of morality, says Curtis. We are disgusted by social “parasites” just as we are by sources of (literal) disease and infection. Our disgust at immoral behavior makes us shun perpetrators, who in turn become ashamed and less likely to break moral rules in the future.
And according to psychologist Paul Rozin:
[Disgust] is deeply connected with the ideas of contagion and contamination rather than with genuine sources of disease. For example, Rozin and his colleagues found that adults would not eat chocolate that had been formed into the shape of dog feces. The disgust aroused by poop was transferred onto the harmless (and delicious) chocolate. According to Rozin, the things that disgust us are not only those that might make us sick, but also those things that remind us of our animal nature. Humans eat, excrete, and copulate like other animals. Yet we are deeply uncomfortable with the idea that we are, in fact, animals, and like all other animals, we’re destined to die. Disgust functions as a “defense mechanism” to keep awareness of our animal nature and our mortality at bay. Once disgust is in place as a “guardian” of the physical body, it can be elicited not only by things that could make us ill, but by very different kinds of stimuli. Each human culture “co-opts” disgust, says Rozin, and projects the emotion onto people and behavior it considers immoral, even if they present no significant risk of disease.