Clare Batty

It is often said that our sense of smell is not very good. What typically follows such a claim is an intraspecies comparison to human vision, an interspecies comparison to animal olfaction, or both. The former comparison has been the focus of a recent debate in the philosophical literature on olfaction, while the latter, though unexplored in philosophy, has recently been challenged in its scientific counterpart. In this paper, I consider each of these discussions. As we will see, in thinking critically about the content of both of these comparisons, we arrive at multiple ways to understand the claim that human olfaction is inferior, or, as it is sometimes put, informationally poor. However, I will show that, in doing so, we also arrive at multiple ways to vindicate the richness of human smell.

Philosophers have largely ignored diachronic olfactory experience in favor of conceiving of it synchronically. Although by no means uncontroversial, the motivation for this restriction stems from the observation that, conceived of synchronically, olfactory experience lacks something that visual experience enjoys—a certain kind of spatial differentiation, largely characterized in the literature in terms of the individuation of objects by their spatial properties. Recently, Aasen (2018) has argued that the claim that synchronic olfactory experience lacks perceptual organization does not amount to the claim that it is aspatial—or, as some have suggested, even minimally spatial. Aasen's main target is my own view (2010a, 2010b, 2010c). In this paper, I explore her argument. I argue that there is much more agreement and convergence between us than she recognizes and that, in turn, this demonstrates the utility of the empirically-inspired model on which my own theorizing has drawn—namely, Wilson and Stevenson's (2006, 2007) object recognition model of olfaction.

Contemporary philosophical discussions of olfaction are dominated by two issues: (1) whether olfactory experience is spatial and (2) whether it represents objects. Although it might seem that these two questions are related, discussion has centered on whether the representation of space is necessary for object representation in olfaction. In this paper, we introduce an olfactory analogue of P.F. Strawson’s discussion of a world consisting entirely of sounds. We draw on the analogue of Strawson’s discussion and the results of recent olfactory experiments in Bao et al. (2019) to consider the role that olfactory experience could play in supporting a conception of an objective world consisting entirely of odours. We conclude that, in order to form a conception of persisting, re-identifiable odours, we would need, as Strawson concludes, to draw on the ways other senses relate us to a three-dimensional space in which material objects (i.e., odour sources) are basic.

Up until the early 2000s, philosophical discussions of olfaction were rare. However, the recent effort to explore, and assess, the dominant visual model of theorizing about perception has produced a substantial and growing body of philosophical work on olfactory perception. When I began writing my dissertation on olfaction in 2004, there were very few substantial philosophical discussions of smell to turn to. There was Thomas Reid’s chapter “On Smelling” in his Inquiry into the Human Mind (2000 [1764]). There was Moreland Perkins’ chapter on smell in his Sensing the World (1983). And there was William Lycan’s work in Consciousness and Experience (1996) and the “The Slighting of Smell” (2000). Thank goodness for all of these, but, as I went on to write primarily on the representation of objects in olfactory experience, Lycan’s work on olfaction was particularly influential in the development of my views. In the years since, the philosophy of olfaction has grown considerably largely because of Lycan’s initial work on olfaction. But despite my own focus on olfactory content, and the other work that has followed in recent years, Lycan’s Layering Thesis has unfortunately received very little uptake in the ensuing debates. The focus has been, rather, on observations Lycan makes in “The Slighting of Smell.” In this chapter I aim to rectify this imbalance, and showcase the thesis’ explanatory power, by setting it against the background of an underexplored area of the philosophy of olfaction—one driven by observations of interspecies similarities and differences in olfactory capability.

We can learn much about perceptual experience by thinking about how it can mislead us. In this paper, I explore whether, and how, olfactory experience can mislead. I argue that, in the case of olfactory experience, the traditional distinction between illusion and hallucination does not apply. Integral to the traditional distinction is a notion of ‘object-failure’—the failure of an experience to present objects accurately. I argue that there are no such presented objects in olfactory experience. As a result, olfactory experience can only mislead by means of a kind of property hallucination. The implications of my arguments are twofold. First, we see that accounts of representational content cannot always be based on the visual model. And, secondly, we see that we must recast the notion of nonveridicality, allowing for a notion of non-veridical experience that is disengaged from any particular object.

Seattle rain smelled different from New Orleans rain…. New Orleans rain smelled of sulfur and hibiscus, trumpet metal, thunder, and sweat. Seattle rain, the widespread rain of the Great Northwest, smelled of green ice and sumi ink, of geology and silence and minnow breath.— Tom Robbins, Jitterbug PerfumeMuch of the philosophical literature on perception has focused on vision. This is not surprising, given that vision holds for us a certain prestige. Our visual experience is incredibly rich, offering up a mosaic of apparent three-dimensional objects. For this reason, it is commonplace to suppose that visual experience is world-directed, with the view taking its most popular form in the representational, or content, view. World-directed views contrast with what we might call subjectivist views — views according to which experiences are raw feels or mere sensations.

This paper considers what olfactory experience can tell us about the controversy over qualia and, in particular, the debate that focuses on the alleged transparency of experience. The appeal to transparency is supposed to show that there are no qualia—intrinsic, non-intentional and directly accessible properties of experience that determine phenomenal character. It is most commonly used to motivate intentionalism—namely, the view that the phenomenal character of an experience is exhausted by its representational content. Although some philosophers claim that transparency holds for all of the sense modalities, any detailed discussion of it focuses on vision. But transparency seems unintuitive for olfactory experience. This paper argues that olfactory experience is indeed transparent and that explanations of what transparency is have been obscured by a reliance on the visual model. In this way, the paper clarifies and advances the debate about transparency.

Much of the philosophical work on perception has focused on vision. Recently, however, philosophers have begun to correct this ‘tunnel vision’ by considering other modalities. Nevertheless, relatively little has been written about the chemical senses—olfaction and gustation. The focus of this paper is olfaction. In light of new physiological and psychophysical research on olfaction, I consider whether olfactory experience is object-based. In particular, I explore the claim that “odor objects” constitute sensory individuals. It isn’t obvious—at least at the outset—whether they meet the widely accepted principles of object individuation and recognition at work in the visual and auditory cases. Among the general issues I consider, then, is whether these traditional principles form necessary, or simply sufficient, conditions on object perception. As we see, at the very least, considering the object-recognition model of olfaction challenges us to look more closely at well-entrenched models of object perception. But the payoff of doing so is high. We not only learn something about a modality that philosophers have historically neglected; by asking new questions and challenging old assumptions, we also further our understanding of perception in general.

In philosophical discussions of the secondary qualities, color has taken center stage. Smells, tastes, sounds, and feels have been treated, by and large, as mere accessories to colors. We are, as it is said, visual creatures. This, at least, has been the working assumption in the philosophy of perception and in those metaphysical discussions about the nature of the secondary qualities. The result has been a scarcity of work on the “other” secondary qualities. In this paper, I take smells and place them front and center. I ask: What are smells? For many philosophers, the view that colors can be explained in purely physicalistic terms has seemed very appealing. In the case of smells, this kind of nonrelational view has seemed much less appealing. Philosophers have been drawn to versions of relationalism—the view that the nature of smells must be explained (at least in part) in terms of the effects they have on perceivers. In this paper, I consider a contemporary argument for this view. I argue that nonrelationalist views of smell have little to fear from this argument.

The philosophy of perception has been dominated by vision, with very little discussion of the chemical senses – olfaction and gustation. In this second entry of a pair on olfactory experience, I consider what olfaction has to tell us about two issues: the nature of perceptual objects and the nature of perceptual properties and, in particular, the secondary qualities. Given the scant work on olfaction in the philosophical literature, my discussion not only surveys what philosophers have said about olfaction so far, but considers the most plausible views and/or most pressing questions in each area of inquiry.

Much of the philosophical work on perception has focused on vision. Recently, however, philosophers have begun to correct this ‘tunnel vision’ by considering other modalities. Nevertheless, relatively little has been written about the chemical senses—olfaction and gustation. The focus of this paper is olfaction. In this paper, I consider the question: does human olfactory experience represents objects as thus and so? If we take visual experience as the paradigm of how experience can achieve object representation, we might think that the answer to this question is no. I argue that olfactory experience does indeed represent objects—just not in a way that is easily read from the dominant visual case.

In this paper, we present new cases of illusion and hallucination that have not heretofore been identified. We argue that such cases show that the traditional accounts of illusion and hallucination are incorrect because they do not identify all of the cases of non-veridical experience that they need to and they elide important differences between cases. In light of this, we present new and exhaustive definitions of illusion and hallucination. First, we explicate the traditional accounts of illusion and hallucination. We then proceed to outline cases of pure property experience—that is, experience as of properties, but not as of objects. We suggest that some might find it to be plausible that olfactory experience is of this kind. We argue that, within instances of such pure property experience, one can identify cases of veridical property perception, illusory property perception and hallucinatory property experience. With these distinctions in hand, we re-examine ordinary cases of experiences as of objects having properties. Drawing on the ideas uncovered by considering pure property experience, we bring to light many new cases of illusion and hallucination within ordinary experience as of objects having properties. These consist in different combinations of veridical perception, illusory perception and hallucination of both objects and properties. In order to accept that these new cases of illusion and hallucination exist in ordinary experience as of objects having properties, nothing turns on accepting the idea that there is pure property experience, or that olfactory experience is an instance of it. Such a conception of experience is simply a tool—a ladder to gain a good vantage point from which one can appreciate that there are these further cases. But this is a ladder that, as Wittgenstein might say, can be thrown away once it is used. Identifying new instances of illusion and hallucination provides much needed, important data for testing theories of experience and perception—theories that are frequently motivated, and should be judged, by their ability to account for cases of illusion and hallucination.

Much of the philosophical work on perception has focused on vision. Recently, however, philosophers have been turning their attention to the ‘other modalities’. In a pair of entries, I consider olfaction—a sense modality that, along with gustation, has been largely overlooked by philosophers. In this first entry, I consider the challenge that olfactory experience presents to upholding a representational view of the sense modalities. It is common for philosophers to think that visual experience is world‐directed and, in particular, that it is representational. World‐directed views contrast with subjectivist views—views according to which experiences are raw feels or mere sensations. Unlike visual experience, olfactory experience doesn't obviously support a representational view. Indeed, given its phenomenology, a subjectivist view of olfactory experience might seem unavoidable. But it is not. Once we begin to unravel ourselves from the dominant visual model of perception, we see that there is a representational view available that honors the phenomenology of olfactory experience. In turn, we learn that although there are some basic similarities between visual experience and olfactory experience, there are significant differences that prevent us from making easy generalizations from the visual case.

In this essay, I review Matthew Fulkerson's The First Sense: A Philosophical Study of the Sense of Touch. In this first philosophical book on the sense of touch, Fulkerson provides an account of the nature and content of tactual experience. Central to Fulkerson's view is the claim that exploratory action plays a fundamental role in touch. In this review, I put pressure on two of his arguments: the argument that tactual experience is unisensory and the argument that tactual experience does not depend on explicit bodily awareness.

In "What the Nose Doesn't Know", I argue that there are no olfactory illusions. Central to the traditional notions of illusion and hallucination is a notion of object-failure—the failure of an experience to represent particular objects. Because there are no presented objects in the case of olfactory experience, I argue that the traditional ways of categorizing non-veridical experience do not apply to the olfactory case. In their place, I propose a novel notion of non-veridical experience for the olfactory case. In his (2011), Stevenson responds to my claim that there are no olfactory illusions. Although he agrees that it is natural—or at least commonplace—to think there are no olfactory illusions, he argues that there are and provides examples of them, many of which he suggests have analogues in the visual and auditory domains. In this paper, I examine the nature of the disagreement between us. I argue that Stevenson fails to argue against my conclusion that there are no olfactory illusions.