Itchy and Scratchy

I never actually knew what itching was for, so I looked it up. According to this article, it’s thought to be an evolutionary mechanism that is sending the signal something is happening on your skin that’s like a bug crawling on your skin, so go flick that bug off before it bites you. (Of course, as is often the case with such mechanisms, it generates more false alarms than genuine ones.)

backscratcher

Interesting. But this next paragraph bugged me (pun not originally intended):

The same fibers that send itching signals are also used to send pain signals to the brain, which once led some scientists to believe that itching was a form of light pain. That notion has since been dispelled by research, which showed that pain and itching elicit opposite responses. Pain causes us to withdraw and itching causes us to scratch.

Now I haven’t read the research the article refers to; there may be better arguments in it than the one described here. But the one described here is not impressive.

First, and most obviously: pain just doesn’t always cause us to withdraw; sometimes it does, but there are many different kinds of pain. People usually clutch their heads when they have headaches, for example; that’s the opposite of withdrawing.

Moreover, even if, counterfactually, all pains did in fact cause withdrawal behaviour, it’s not obvious that this fact should be regarded as part of the essence of pain. What’s essential to pain, surely, is that it makes us want to avoid doing whatever causes the pain; but wanting to avoid touching the location of the pain seems a distinct and accidental feature (since touching the location of the pain does not always necessarily increase the pain).

In any case, if you find that case X differs from standard cases of Y by lacking feature Z, you’re then faced with a choice of either denying that X is a Y or denying that feature Z is essential to being a Y. In this case, then, scientists were faced with the choice between either denying that withdrawal behaviour is essential to pain or denying that an uncomfortable sensation that inherently makes us want to get rid of it counts as a pain. Which is the more plausible choice?

You want proof?  I'll give you proof!

More broadly, while the question of what physiological mechanisms underlie pain is presumably an empirical, natural-scientific question, the question of whether a particular kind of sensation is a pain seems more like a conceptual, philosophical question to which scientific “research” is irrelevant.

Here’s my argument for that claim. Suppose that scientific experts announced tomorrow that headaches are not actually a form of pain. (I choose headaches because they’re more paradigmatically a form of pain than itches.). Headaches may feel like pains, these experts aver, but they’re really not pains, because they involve neuronal thingummy B instead of neuronal thingummy A. Would you take this seriously? Surely not, because feeling like pain is simply what we mean by pain – it’s part of the conceptual grammar of the term. Anyone who talks of something’s feeling like pain but not being pain would have to be using the word “pain” with a new, nonstandard meaning, just as someone who talked of something’s being a regular quadrilateral but not a square would have to be using the word “square” with a new, nonstandard meaning. (Or else using some of the other words in the sentence nonstandardly.)

The researchers described in this article may well have confused constitutive with enabling conditions. And that takes me to a broader grump about scientists, namely, that scientists tend to be unaware that there is such a thing as a philosophical objection to a thesis. They tend to assume that anything that sounds like a coherent hypothesis (such as the possibility of time travel, or the suggestion that the universe we live in is actually 2-dimensional – to pick a couple of actual examples) is thereby fit for empirical investigation, without considering that in such cases a) there is a prior question as to whether the thesis so much as makes sense (for if it does not, then those who take themselves to be performing an empirical investigation of it will actually not be investigating anything – or at least not that), and b) the training and tools to determine whether it does makes sense are the specialisation of a field other than their own.

(But then, a still more egregious problem is the philosophers who are confused about this.)

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13 Responses to Itchy and Scratchy

  1. Little Alex May 17, 2010 at 12:58 pm #

    Not to mention the obvious: self-controlling pain carries high potential for momentary euphoria. The generic example is the teenage girl who cuts herself. The depression is very painful — subjectively, but there’s also the deficiency of natural sources of arousal, pleasure, comfort, etc. — and so is the cutting. The cutting forces the pain that forces endorphins to trigger. Headaches, like the bug-like feeling under the skin, are normally related to physical deficiencies, right? (As opposed to an positive inducement of pain.)

  2. Joel May 17, 2010 at 3:32 pm #

    Anyone who talks of something’s feeling like pain but not being pain would have to be using the word “pain” with a new, nonstandard meaning, just as someone who talked of something’s being a regular quadrilateral but not a square would have to be using the word “square” with a new, nonstandard meaning.

    Which is true, but colloquial use doesn’t confer identity. Otherwise there’s the logistical problem of how all those Dutch got to Pennsylvannia.

    Headaches may feel like pains, these experts aver, but they’re really not pains, because they involve neuronal thingummy B instead of neuronal thingummy A. Would you take this seriously? Surely not, because feeling like pain is simply what we mean by pain.

    There can be false bundling in the concept of pain that some scientist discovers upon close examination, and s/he may want to “preserve” the concept by altering it enough to be consistent with observed phenomena, but in some sense still the thing people “really” mean when they say “pain.” It’s not all that odd to consider that there might be several phenomena that we choose to bundle together. If the “pain” doesn’t meet the criteria, then the sensing party’s identification is wrong because they are either using the new “pain” incorrectly or implicitly equating things which _aren’t_ the same, both of which are empirical questions.

    It’s minor objection, that doesn’t really change your grump, even if true, but I just felt like saying it.

    • Roderick May 17, 2010 at 3:43 pm #

      There can be false bundling in the concept of pain

      We can certainly make the mistake of thinking that phenomena that are similar in their appearance are similar in other, deeper properties. But it’s hard to see how that applies to phenomena that are defined by how they appear.

      • Roderick May 17, 2010 at 4:36 pm #

        Also:

        colloquial use doesn’t confer identity

        Well, use never confers identity, but it can specify it. And I think our use of the term “Pennsylvania Dutch” does specify the identity of what it’s referring to; it’s just that that use is different from our use of the term “Dutch” by itself. The Pennsylvania Dutch aren’t Dutch, just as a hot dog isn’t a dog; but it’s not as though something other than use specifies what “dog” and “hot dog” refer to.

  3. Anon73 May 17, 2010 at 5:55 pm #

    I’ve always been curious what you think the “philosophical presuppositions” of science are, and when scientists need to defer to philosophers. Most scientists I’ve met would be more likely to tell a self-described “philosopher” to finish bagging their groceries before taking their objections seriously. Ever since Aristotle came up with his theory of causes and elements and modern science disproved it I take it scientists are generally disdainful of philosophers in general.

    • Roderick May 17, 2010 at 6:33 pm #

      Well, there’s certainly a long history of philosophers mistakenly trying to settle empirical questions conceptually. But there’s also a long history of scientists mistakenly trying to settle conceptual questions empirically. The problem is that scientists know about the first type of case but not the second.

      • Anon73 May 17, 2010 at 7:32 pm #

        Recommended reading if at all possible? This is a provocative subject considering how science is regarded today (I hesitate to use words like “scientism”, but that’s probably more descriptive than any.)

  4. MBH May 17, 2010 at 9:42 pm #

    Very helpful.

  5. E5 May 18, 2010 at 9:24 am #

    So it seems like this whole issue could have been avoided if the original author presented his definition of “pain”, more likely than not it isn’t the same thing as headaches, emotional pain, etc.

    Taking issue with such a trivial point provides incentive for authors to opt for more technical jargon as opposed to common terms that are *almost* the same thing as the technical jargon, if for no other reason it prevents armchair scientists from nitpicking word usage.

  6. Anna O. Morgenstern May 18, 2010 at 8:13 pm #

    Thank you for writing this Roderick. You elaborated something I’ve been trying to get some of my friends who are a bit too enthusiastic about pop science to understand.
    “And that takes me to a broader grump about scientists, namely, that scientists tend to be unaware that there is such a thing as a philosophical objection to a thesis. They tend to assume that anything that sounds like a coherent hypothesis (such as the possibility of time travel, or the suggestion that the universe we live in is actually 2-dimensional – to pick a couple of actual examples) is thereby fit for empirical investigation, without considering that in such cases a) there is a prior question as to whether the thesis so much as makes sense (for if it does not, then those who take themselves to be performing an empirical investigation of it will actually not be investigating anything – or at least not that), and b) the training and tools to determine whether it does makes sense are the specialisation of a field other than their own. “

  7. Bruce May 19, 2010 at 4:48 am #

    Not to mention the obvious: self-controlling pain carries high potential for momentary euphoria. The generic example is the teenage girl who cuts herself. The depression is very painful — subjectively, but there’s also the deficiency of natural sources of arousal, pleasure, comfort, etc. — and so is the cutting. The cutting forces the pain that forces endorphins to trigger. Headaches, like the bug-like feeling under the skin, are normally related to physical deficiencies, right? (As opposed to an positive inducement of pain.)

  8. Matt Flipago May 25, 2010 at 1:39 am #

    “Headaches may feel like pains, these experts aver, but they’re really not pains, because they involve neuronal thingummy B instead of neuronal thingummy A. Would you take this seriously? Surely not, because feeling like pain is simply what we mean by pain.”

    The funniest thing is this idea is definitely believed by some. Many consider spiciness not to be a taste, only because it is not through the same neural transmitters.

    • Roderick May 25, 2010 at 7:46 am #

      I guess the ideas of compositional plasticity and multiple realisability, which were hailed with such enthusiasm in the 70s, still haven’t really gotten their message through.

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