Sometimes the philosophical armchair gets bumped by empirical facts. So it is when thinking about pain. For good or ill (good, actually, as we shall see) most of us are intimately acquainted with physical pain, the kind you feel when you stand on a nail or burn your hand. And, from the armchair, it can seem blindingly obvious that pain is essentially unpleasant. There are of course unpleasant experiences that aren’t pains – nausea or itches, for example – but surely there aren’t pains that don’t hurt, pains that are neutral or even pleasurable rather than unpleasant. Surely, indeed, there couldn’t be. For it is part of the very concept of a pain that a pain be unpleasant. Or so it has seemed to many. Yet over recent decades philosophers’ confidence in these putative truisms has been shaken by some fascinating cases from the clinic, the lab, and life.

Actually, many of the cases supposed to threaten our confidence in pain’s essential unpleasantness really shouldn’t. Consider congenital pain insensitives, people who from birth cannot feel when their bodies are under stress or being damaged. Theirs is a fascinating though tragic condition: they tend to die young, a testament to pain’s value in motivating us to act so as to minimize injury. But the evidence isn’t that pain insensitives feel neutral pain; it’s that they don’t feel pain at all. The same seems true of soldiers who in combat receive terrible injuries they appear not to notice, or indeed civilians who get bitten by sharks, say, and report feeling massive pressure but, at first, no pain. Their testimony suggests these too are no-pain, not neutral-pain cases. Common sense remains intact.

Pre-frontal lobotomy, once used as a last-resort treatment for chronic pain, might seem more of a threat to common sense. The lobotomized sometimes say they still feel the chronic pain they felt before the lobotomy, but are no longer “bothered” by it. But even this need not shake our armchair convictions. For we should distinguish between the primary unpleasantness of pain, as we might call it, and the emotional suffering that pain and its unpleasantness tend to cause, such as the anxiety we all sometimes feel about what the cause of an intractable pain might be, or about whether its unpleasantness might become intolerable. It is arguably such anxiety, and not pain’s primary unpleasantness, that lobotomy eliminates. In short, lobotomy patients still have unpleasant pains – hence their reacting normally to pin-pricks – but they worry about them less.

What about masochists? Some people like to eat very hot food; others like to be whipped in certain, sometimes elaborate, sexual contexts. Why? Do these activities, in these contexts, and in these people cause pains that are pleasant rather than unpleasant? I don’t think so. Some philosophers claim that, thanks to the charged contexts involved, sexual masochists – like the soldier in combat – feel no pain at all. But I suspect masochistic activities often do cause pain, indeed unpleasant pain. Unpleasant pain seems to be part of what the masochist wants. But it might yet be that masochists seek such pain in those contexts because in those contexts it is a means to other things the masochist wants, including certain pleasures. Unpleasant pain can, for instance, heighten pleasures felt alongside it (partly because of its effect on our attention). Or, to take another example, unpleasant pain in the right context can sustain the make-believe, which some sexual masochists seek, that they are subordinate to another person.

Part of the point of pain’s unpleasantness is surely the way it motivates us to act in injury-avoiding ways. The story just told might seem incompatible with that idea. But it isn’t. The aversive motivation of pain’s unpleasantness is still present when the masochist is whipped; some aversive behavior might be too, if for instance the masochist flinches. But the aversive motivation is, though present, largely overridden by the masochist’s desire for things to which the unpleasant pain is a means.

So our common sense idea that pain is essentially unpleasant can handle such cases. But another case, I think, looks poised to deliver the armchair an almighty knock. In 1928, Austrian psychiatrists Erwin Stengel and Paul Schilder discovered an exceptionally rare and weird condition, caused in adults by strokes and brain tumors, which they called “pain asymbolia”. Investigating it, Stengel and Schilder and their successors inflicted on their patients a great variety of what are mildly called “noxious stimuli”. They pinched them, pricked them with pins, gave them electric shocks, and immersed their hands in hot and cold water. Their patients, as you might expect, reported pain. But, remarkably, they said and did nothing to indicate the pain was unpleasant. On the contrary, they said the pain did not “bother” them, that it was “nothing”. They did not grimace or wince, or withdraw from the pinchings or prickings, nor did they resent those who pinched and pricked them. Is this at last a case of pains that don’t hurt?

How might the guardians of common sense try to handle this case? Might they compare it to congenital pain insensitivity and say that asymbolics feel no pain at all? This looks unpromising, since asymbolics say they feel pain, and it is not clear what grounds we have to doubt them. They seem sincere and, since they had normal pains before their strokes, which they described normally, they appear to understand the concept of pain.

Another tack would be to compare asymbolics to the lobotomized and say that what is missing from their experience is not pain’s primary unpleasantness, but only the downstream emotional response to that unpleasantness (e.g. anxiety about what it means or how unpleasant it will become). But, while this emotional response is indeed missing, if it were all that was missing, and the pains themselves remained unpleasant, asymbolics would surely withdraw from the pinchings and prickings just as the lobotomized do, and they would surely tell us their pains were unpleasant. Yet they don’t.

Might the story we told about masochism illuminate asymbolia? Perhaps asymbolics fail to withdraw from the pinchings and prickings not because their pain is not unpleasant, but because unpleasant pain is a means to something else they want. But what might that be? It’s quite unclear. And, again, if their pain is unpleasant, why do they say it doesn’t bother them?

So in the case of asymbolia our earlier strategies seem incapable of protecting the armchair intuition that pain is essentially unpleasant. Here, then, is a new idea: might it be that, while asymbolics’ pains are unpleasant, their brain damage has made them cease to care about the unpleasantness? In particular, might their brain damage somehow have eliminated the normal human desire (overridable by other desires, of course) not to undergo unpleasant experiences? According to this idea, asymbolia involves not neutral pain, but pain whose unpleasantness has – thanks to that eliminated desire – lost its motivational oomph.

But, again, asymbolics speak as if their pain is not unpleasant, not as if its unpleasantness has merely lost its oomph. The suggestion, moreover, seems be that unpleasant pain’s motivational power – its capacity to move us to action – normally depends on one’s having a desire for the unpleasantness to cease. But that contradicts an idea many find compelling: that unpleasantness is itself a motivational property of experiences, that unpleasant experiences are themselves motivational states, requiring in particular no further desires to move us, not even the basic desire to avoid unpleasantness. That idea doesn’t mean we always act on unpleasant experiences, of course. If you drop your wedding ring in a freezing pool, you might plunge your hand further into the icy water despite the pain. But that shows only that one motivation (to recover the ring) can trump another (to lift your hand), not that unpleasantness is not a motivation.

In short, all these strategies seem incapable of handling the odd things asymbolics do when pinched, pricked, and the rest – when, that is, things are done to them that would cause pain in you and me. Moreover, even if these strategies did better on that front, there would still be the following problem. As we have seen, asymbolics say and do odd things when given stimuli that would normally cause unpleasant pain. But the literature also indicates further abnormalities that, by contrast, appear to have nothing do with unpleasantness or its absence. For one thing, they self-harm: placing their hands in flames, pricking themselves, and jamming things into their eyes. For another, they are unresponsive to the sight or sound or verbal warning of threats to their bodily integrity. When Stengel and the others came at them with hammers, knives, and needles, for instance, they didn’t respond fearfully or aversively. One of Stengel’s patients was almost run over because, although he recognized a noise as the horn of a truck bearing down on him, he failed to respond. None of our earlier strategies looks to have anything at all to say about these abnormalities.

Put it this way: even if asymbolics felt no pain at all, or had unpleasant pains they took to be means to some further end, or unpleasant pains absent the usual downstream anxieties, or absent the usual desire to be free of unpleasantness – again, even if any of those things were true, as per our earlier suggestions, would we not still expect asymbolics to try to avoid bodily damage, hence to respond to the sights and sounds of bodily threats? After all, humans do not avoid bodily damage only to avoid unpleasant pain, or the anxieties caused by such pain, or the frustration of our desires to be free of such pain. Even pain insensitives try (albeit with great difficulty) to avoid bodily damage despite being completely incapable of pain. So, again, why do asymbolics not respond normally to verbal warnings and the sights and sounds of bodily threats? The strategies we’ve examined don’t say.

What we are lacking, then, is a unified account that illuminates both sets of abnormalities: the odd things asymbolics do and say when subjected to things that would cause others pain, and their unresponsiveness even to the sights and sounds and verbal warning of bodily threats, for example to the sight of a needle being jabbed at their eyes.

At this point, American philosopher Colin Klein makes a nice suggestion: that asymbolics’ brain damage has made them incapable of a basic kind of caring about their own bodily integrity. This is not, notice, the earlier idea that they don’t care about their pain’s unpleasantness; the suggestion now is rather that they don’t care about their bodies. And that looks like just what is needed to explain their further abnormalities. Why don’t they flinch when a pin is jabbed at their eyes? Why don’t they react when told they are about to be harmed? Why do they self-harm? Because their brain damage has eliminated their capacity for a basic kind of care the rest of us have for our own bodily integrity.

But what about the asymbolic’s original abnormalities: the odd things they do and say when pinched, pricked, and the rest? These seemed to undermine our armchair intuitions by indicating that asymbolics are having pains that don’t hurt. If Klein’s proposal is to offer an alternative, the idea must be that, even though the pains caused in asymbolics by the pinchings and prickings actually are unpleasant, asymbolics still don’t withdraw because they don’t care about their own bodies. But why should this be? Why would not caring about her body stop an asymbolic withdrawing if the pinchings and prickings really were causing her suffering? Avoiding unpleasant pain is not the only reason to avoid bodily threats, but it is surely one reason. People with the condition known as allodynia are caused agonizing pain even by innocuous touches, and naturally they withdraw from such touches even when they know them to be harmless. So if the asymbolic really is experiencing unpleasant pain, we should expect her to withdraw from the pinchings and prickings even if she doesn’t care about her body. Yet she doesn’t.

It is time, I think, to conclude that the philosophical armchair has been well and truly bumped. Pain is not essentially unpleasant. There not only could be but are neutral pains. Asymbolics have them. To put it another way, your unpleasant pains comprise two components: a pain experience, in virtue of which you count as feeling pain, and some further ingredient, in virtue of which that experience is unpleasant. Asymbolics, because of their brain damage, are missing that further ingredient. That’s why they don’t withdraw from pinches and pin-pricks. For fifty years or so, scientists have endorsed roughly this composite conception of unpleasant pain. Philosophers, rightly, are beginning to follow suit.

But might asymbolia do more for us than undermine the armchair conception of pain? Might it actually throw some light on the mysterious “further ingredient” that makes pains – and perhaps other experiences – unpleasant? It might.

To begin to see this, notice that the idea that asymbolics are undergoing neutral – not unpleasant – pains does nothing to explain their further abnormalities: their not flinching from pins jabbed at their eyes, for instance, and their not getting out of the way of trucks. So we still don’t have the unified account of all the asymbolic’s abnormalities we were seeking. Might it help to return to Klein’s idea that asymbolics are incapable of caring about their bodies? This idea looked perfectly suited to explaining their further abnormalities, remember, but not so good at explaining why they might fail to respond to their pain’s unpleasantness. But might we be able to use Klein’s idea instead to explain why their pain is not unpleasant. If so, we might finally have the unified explanation we want: asymbolics’ inability to care about their bodies would explain both their not flinching from those eye-bound pins and their pains’ lack of unpleasantness and hence their not withdrawing from pinches and pricks.

But why should their not caring about their bodies mean their pains are not unpleasant? This, admittedly, is far from obvious. But perhaps it is far from obvious only because we haven’t thought enough about what makes normal pains unpleasant. When philosophers first endorsed the composite conception of unpleasant pains, distinguishing neutral pain experiences from the “further ingredient” that makes them unpleasant, they said much more about the pain experiences than the “further ingredient” – as if, having realized that pain doesn’t essentially hurt, they had forgotten that it nevertheless usually does. But recently the “further ingredient” has started to get the attention it deserves. Is there an account of it that would make our explanation of asymbolia work?

The traditional account of pain’s unpleasantness, advanced by David Armstrong more than 60 years ago, says that your pain is unpleasant when and because you want it to stop for its own sake. The idea is not that your desire affects the pain, making it unpleasant, but that all we mean in calling an experience of yours unpleasant is that you want it to stop for its own sake, that you dislike it (in that sense). “For its own sake” is important. You might want a gorgeously pleasurable back rub to stop because it is distracting you from your work, but this isn’t wanting the experience to stop for its own sake; it is wanting it to stop so you can get on with your work. So it doesn’t contradict the theory.

Would the traditional view, if true, allow us to understand why asymbolics’ failure to care about their own bodies might eliminate their pains’ unpleasantness? Well, the view does allow the question to be re-phrased: why might asymbolics’ lack of care for their own bodies prevent their wanting, for its own sake, their pains to cease? But the re-phrasing doesn’t help, unfortunately, since it remains hard to answer the question, hard to see why a person’s not caring about her own body would stop her wanting her pain (an experience) to cease.

So let’s turn instead to imperativism, an account of pain’s unpleasantness that has come onto the scene in the last decade or so. Imperativists draw the following contrast between the experiences we have when we see things, on the one hand, and our pains, on the other Your visual experiences only tell you (rightly or wrongly) how the world is, for example that there is an apple before you. But pains tell you what to do. They are imperatives or commands. Pains do convey information, some imperativists think, telling you perhaps that your hand is damaged; but what makes them painful and motivating is that they (also) tell you what to do, for example to lift your hand from the candle flame. Pains, in short, are commands issued, as it were, by the body; and it is because of their being such commands that they hurt.

Would this view, if true, help us understand why failure to care about their own bodies might eliminate the unpleasantness of asymbolics’ pains? Well, as before, it allows the question to be re-phrased: why might asymbolics’ failure to care about their own bodies prevent their bodies from commanding them to (say) withdraw their hands from candle flames? But, as before, the re-phrased question remains hard to answer. For why should an asymbolic’s not caring about her own body mean that her body no longer issues pain-commands? Suppose, not caring about your car, I repeatedly kick it. My not caring won’t prevent you from telling me to stop. Or at least it won’t if you think your command will motivate me to stop, which is what imperativists think pain-commands do (pain-commands, they think, are inherently motivating). In short, imperativism doesn’t help.

Consider, then, evaluativism, a final account of pain’s unpleasantness, a view I happen to like. Evaluativists agree that an unpleasant pain conveys information: it informs or misinforms you that a part of your body is damaged. And they agree it also does more than this; but the further thing they think it does it to evaluate that damage as bad for you. Your unpleasant pains don’t just informyouof damage; they evaluate the damage; they inform you of its significance for you. And it is in virtue of this evaluation that they are unpleasant and motivational. In short, your pain hurts because it involves your actually experiencing a bodily state as bad for you.

Would thisfinal view, if true, help us understand why asymbolics’ failure to care about their own bodies might eliminate their pains’ unpleasantness? Well, unlike its predecessors, yes, it just might! To see this, notice that you will think that a thing’s being damaged is bad for you only to the extent that you care about that thing. If I start kicking your car again, is that bad for you? You’ll think so only if you care about your car. Now, admittedly, pains are experiences, not thoughts; but the evaluativist could say that the same point carries over: you’ll experience damage to your body as bad for you only if you care about your body. Now, you and I do care about our bodies, so we do experience bodily damage as bad for us, hence our pains are unpleasant (since that’s what the unpleasantness of pain consists in). But if asymbolics don’t care about their bodies, as we wanted to say, borrowing Klein’s idea, then they won’t experience damage to their bodies as bad for them, hence their pains won’t hurt. They will, notice, still experience the damage, so they will still feel pain (since that is what pain is); but, since their experiences doesn’t represent that damage as bad for them, their pain won’t be unpleasant.

Also, don’t forget, since they don’t care about their bodies, asymbolics also won’t flinch from eye-bound pins, or try to get out of the way of trucks. So evaluativism looks like it might just allow us to squeeze what we wanted out of the idea that asymbolics lack a basic kind of care for their own bodies: an illuminating, unified explanation of all their abnormalities.

This hardly proves evaluativism correct, but we evaluativists can count it a nice feature of our view, a view that I think has many other nice features too. Or at least, it looks like we can do this if we have something clever to say about a worry recently raised by French philosopher, Frederique de Vignemont. She invokes another weird and wonderful case: somatoparaphrenia, or alien limb syndrome. People with this syndrome have a limb that feels not to be their own. They can see and feel that it is attached to them, and they have sensation in it, but it still feels alien. Now, sometimes their attitude to their alien limb is one of disgust or hostility. They also appear calm when it is threatened, by contrast with how they feel when any other body part is threatened. Sometimes, moreover, they harm the limb themselves. It can seem, in short, that they don’t care about the alien limb. Yet, de Vignemont notes, they sometimes experience unpleasant pains in it nevertheless! The problem for us is that this doesn’t seem to be what our explanation of asymbolia would predict. To the extent that people with alien limbs don’t care about those limbs, it looks like our approach should predict a kind of localized asymbolia: that these people will be incapable of unpleasant pains in their alien limbs. But they are not.

So the debate continues. Let this final puzzle be today’s homework question. Answers on a postcard, please. (No, really, please.) The bumps from stubborn – sometimes unwelcome – empirical facts keep on coming.

David Bain is Reader in Philosophy at the University of Glasgow and Joint Principal Investigator of the value of suffering project, funded by the John Templeton Foundation.