Pain Perceptual theories

Pain Perceptual theories

Because sense-datum theories are most plausible when applied to intransitive bodily sensations, many philosophers, who believe that a naturalist account of ordinary perception can be given without introducing sense-data, have attempted to understand pains and other bodily sensations as species of ordinary perception (exteroception). The so-called perceptual theories of pain are advanced and defended on the hope that pains and other intransitive bodily sensations, contrary to first appearances, are species of information gathering which work on the same principles that govern other sensory modalities for which a successful direct realist account can plausibly be given.

3.1 Introduction

The core commitment of any perceptual view of pain, put as broadly as possible, is that normally, in having or feeling pain, one is perceiving something extramental. In other words, feeling pain normally involves perceiving something in the same sense in which one perceives a red apple when one sees it in good light. It involves exteroception. Sometimes, in ordinary parlance, the term ‘perception’ is used in conjunction with ‘pain’ as in ‘pain perception’ to mean awareness of pain, or just feeling/experiencing pain. This is introspective use of ‘perception’ and should be sharply distinguished from what the perceptual theorists mean when they claim that feeling pain involves perceiving something. They have exteroception in mind, and we’ll use the term always in this sense.

According to perceptual theorists, when one feels, say, a sharp pain in the back of one’s hand, one perceives some physical feature or condition of one’s hand. The proper modality for this perception is somatosensory, similar to the sensory modality of touch or proprioception (the sensory modality internal to one’s body that informs one about the position and movement of one’s body and body parts). Most perceptual theorists identify this feature with tissue damage or some condition of the tissue that would likely result in damage if sustained in that condition. More abstractly, it is some sort of physical disorder due to some tissue trauma, irritation, inflammation, or some such pathological condition, or a condition close to such. It is also possible to identify the object of perception in pain with the activation of nociceptors innervating the damaged or irritated tissue. (Nociceptors are peripheral nerve endings specialized to respond, normally, only to potentially damaging stimuli, i.e., to nociceptive stimuli). Let’s use ‘tissue damage’ as a stand-in for whatever physical disorderly condition of bodily tissue is being perceived in feeling pain according to perceptual theorists. Normally, when we talk about the location of a pain, we are talking about the location of this perceptual object, i.e., the location where the tissue damage is occurring or about to occur.

Perceptual theories of pain as alternatives to sense-datum theories were first explicitly stated and philosophically developed in the 1960’s. The most influential and prominent defenders were Armstrong (1962; 1968) and Pitcher (1970; 1971). There were others, but in terms of setting the tone and philosophical agenda for the subsequent discussion for decades to come, it is fair to say that no one has surpassed their enormous influence.^[9] At the time, the dominant view was that pains and other intransitive bodily sensations are not perceptual at all, they were conceived to be sensations or experiences (à la sense-datum theories) that are reliably caused by (actual or impending) injury or damage to body tissue or internal organs. They are thus useful warning signals, but they don’t have much in common with standard ways of perceiving extramental world. This view has still some defenders today: although the conception of pains as sense-data has been largely abandoned, those who are not sympathetic to perceptual theories still hold what might be called the “sensation or qualia view of pain”, according to which pain is not a phenomenal object but a phenomenal quality of one’s experience, or alternatively, it is a subjective experience with certain qualia or qualitative character that one is directly aware of when in pain. With this adjustment from object to quality kept in mind, most of what we have said about sense-datum theories above can be applied, mutatis mutandis, to the qualia view of pain.

3.2 The appearance/reality problem

The main source of resistance to a perceptual view of pains comes from the common-sense conception of pain according to which pains are sensations with essential privacy, subjectivity, self-intimation, and incorrigibility. These apparently essential features of pains pose difficulties for any perceptual theory. Indeed, they can be used in advancing anti-perceptualist arguments whose general form can be put in the following way. Genuine perception always involves the possibility of misperceiving the perceptual object that is not essentially private and subjective. In other words, there is always an appearance/reality distinction applicable to the objects of genuine perception which gives rise to the possibility that the perceptual appearance of this object misleads us about what the object is like in reality. The main reason for this is that these objects have a reality beyond their appearances. They are thus public objects and capable of existing on their own without anyone’s perception of them. But feeling pain has none of these features. Therefore, it cannot be genuine perception.

So, how do the perceptual theorists handle this objection, which lies behind the intuitive resistance to treating pain as a form of perception? Given the core commitment of perceptual views (namely, that feeling pain involves perceiving something extramental), one might think that perceptual theorists identify pain with tissue damage. Indeed, if one takes this view, the above objection seems almost decisive against it. But relatively few defenders actually take this route — among the most notable are Newton (1989), Stephens and Graham (1987), and Hill (2004, 2006). Most others, including Armstrong and Pitcher, bowed to common-sense understanding of pain and identified pains with pain experiences or sensations, understood in a direct realist fashion. If pains are identified with experiences, not with their causes (i.e., tissue damage), then the above objection seems to disappear (but see below).

It is primarily for this reason that most perceptual theorists identify feeling pain with having an experience in the first place — just as the pain scientists do (see IASP definition above) following the second thread in our ordinary conception of pain. But this is the experience mediating or involved in the perception of tissue damage. In other words, they grant that the (dominant) concept of pain is the concept of a subjective experience, but they insist that this experience is essentially perceptual: it constitutes our perception of tissue damage. Compare the situation with seeing. In seeing a red apple in good light, I am having a visual experience which is perceptual: it constitutes my seeing the red apple. The difference lies not in the flow of information, but in the locus of our interest and conceptual identification directly induced by the perceptual experience. According to most perceptual theorists, we apply the concept of pain, PAIN, primarily to the perceptual experience we are having, not to the object of this experience, i.e., tissue damage (even though, as discussed above, common sense also uses confusingly the same word ‘pain’ to indicate where the tissue damage might be occurring by applying it to a bodily location — more on this shortly). In other words, ‘pain’ names a subjective experience. In vision, however, the locus of conceptual identification is different: normally it is the object of our visual experience we are interested in, say, a red apple seen in good light and identified as such. Thus, we both perceptually and conceptually focus on it and its visible properties such as its redness, roundness, etc., by applying our concepts, RED, ROUND, APPLE, to it on the basis of our visual experience. Of course, we are sometimes interested in and can focus and report on our visual experiences too, but this happens usually when we are not sure about what we are seeing.

(In what follows, it is useful to denote concepts by capitalized words that name them. So, for instance, ‘RED’ denotes the concept of red which in turn expresses the property of being red. In other words, RED expresses the property of being red, or redness in short. Even though here I assume for convenience a representationalist framework for concepts according to which concepts are mental representations realized in the brain — which is the psychologist’s preferred reading, nothing of any importance hangs on this: the reader may substitute his or her own preferred interpretation of how concepts are to be understood. For instance, concepts may be merely certain sorts of mental or behavioral capacities that are functionally or dispositionally characterized.)

There is thus an asymmetry in our spontaneous reaction to incoming stimuli in seeing and having pain; that is, our spontaneous interest and focus directly resulting from the perceptual experiences is different in each case. We can represent this asymmetry with a schematic (Figure 1).

 
Figure 1: There is asymmetry in concept application even when it is assumed that the structure of information flow is symmetrical in the contrast cases.

Thus the incorrigibility mentioned before reduces to one’s incorrigibility about one’s occurrent experiences. To the extent to which we are incorrigible in discriminating and conceptually identifying our own experiences, to that extent we cannot be wrong about our own pains. Hence the locus of concept application are the pain experiences, even though it might seem to us as if we were applying the concept of pain to bodily locations (see below). It follows that hallucinations or illusions are possible, in one sense, not about feeling/experiencing pain, but about whether these experiences’ correctly representing some tissue damage, i.e., the object of perception in feeling pain.

The privacy and subjectivity of pains are explained similarly. If pains are experiences, they cannot exist without being the state of someone’s mind. In other words, they exist insofar as one has them: they are mental states or events, hence essentially mind-dependent. The privacy of pains again reduces to the privacy of experiences. There may be philosophical problems about how privacy, subjectivity and incorrigibility are possible in a completely physical world, but if there are such problems, they are general problems about having perceptual experience of any kind, not necessarily pertaining to pains and other intransitive bodily sensations.