Yuck!: The Nature and Moral Significance of Disgust

1. Toward a Functional Theory of Disgust

1 Toward a Functional Theory of Disgust 1.1 Introduction One interesting fact about disgust is that it is a piece of human psychology that does not sit easily on either side of the traditional nature–nurture divide. On the one hand, the capacity to be disgusted, together with a small set of things that appear to be universally and innately disgusting, is a part of the species’ typical psychological endowment. These are a part of human nature; one does not have to learn how to be disgusted, and one does not have to be taught to be disgusted by certain things, either—like the pungent smell of rotting garbage on a hot summer day, for instance. On the other hand, the variation evident in what different people find disgusting reveals a considerable role for nurture as well. In other cases, people do learn what to be disgusted by through individual experience, through social interactions with others, and through the type of education that constitutes the refinement of their moral and aesthetic sensibilities. This fact about disgust is just one reason that the emotion has attracted the attention of a wide range of researchers, so that it is now relevant to a number of discussions taking place in different parts of academia. These include philosophic debates about metaethics, sentimentalism, and response dependence (McDowell 1985, 1987; D’Arms and Jacobson 2000, 2005; Knapp 2003; Nichols 2004; Gert 2005), the empirical investigation of morality (Haidt et al. 1993; Haidt et al. 1997; Rozin et al. 1999; Moll et al. 2005; Schnall et al. 2008), examinations of social history (W. Miller 1997), normative and applied ethics (Kass 1997, 2002; Nussbaum 2004a,b; Hauskeller 2006; Douard 2007), and a variety of research projects across the spectrum of psychology. Most of these will come under consideration in the course of this book. In this first chapter, though, the psychological research will serve as the point of departure. 12 Chapter 1 The recent surge of interest and empirical work on the psychology of disgust has been accompanied by only the mildest convergence in theoretical views. Beyond agreement that disgust is a specific type of aversion, the proverbial “dizzying array” of conjectures have been made about its fundamental nature: disgust is a reaction formation, a defense against or rejection of emotional intimacy (S. Miller 1986, 1993); it is a socially constructed moral emotion of exclusion most closely linked to touch and smell (W. Miller 1997); it is a food-based emotion most closely linked to the mouth (Rozin et al. 2008); it is an innate system evolved to protect us from parasites , germs, and disease (Curtis and Biran 2001; Curtis 2007); it is, at least in part, a pan-mammalian adaptation that regulates sexual conditioning (Fessler and Navarrete 2003a, 2004); it underlies a particular kind of social stigmatization (Kurzban and Leary 2001); it helps in demarcating ethnic boundaries (Boyd and Richerson 2005a); it is governed by the laws of sympathetic magic (Nemeroff and Rozin 2000). After only a cursory glance, one might be tempted to wonder whether everyone is talking about the same thing. Closer inspection shows, I believe, that many of these fragments of theory are compatible with each other in interesting ways, but the fact remains that at present there is no single received view, accepted by all interested parties. The closest thing to orthodoxy was Paul Rozin’s view (Rozin et al. 2008). Even that has come under direct attack from various quarters, however; see W. Miller 1997; Charash and McKay 2002; Curtis et al. 2004; Fessler and Navarrete 2005; and chapter 2 of this book. A number of factors have led to the current situation in cognitive scientific work on disgust. One is the seemingly contradictory nature of disgust itself. Another is that the present state of research is marked by a trend familiar from other areas of science and periods of development—the data have recently been accumulating faster than theory has been able to keep up. A final factor responsible for this proliferation of different views is that, like most emotions, disgust is “level ubiquitous” (De Sousa 1987). Roughly speaking, something interesting can be said about its character from nearly every level of analysis, from its associated patterns of neural activation to its role in large-scale cultural dynamics and most points between.1 From the perspective of a theoretician, this is a particularly exasperating source of confusion, since appreciation of level ubiquity can make it unclear where to even begin...