Source: http://wordandobject.com/2007/12/wittgensteins-sensations/
Timestamp: 2019-04-19 04:18:47+00:00

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It would be like having a mental representation of pure color, and not, say, a color swatch, or something of that color (a “thing” in the “world” to which that color truthfully could be attributed).
I can’t perform this extrapolation, and I can’t see how it could be done. I think the best case that can be made for such a hypothetical correspondence theory of sensation is that you compare x (the current sensation) with y (a remembered instance of previously having had a sensation which, for some reason, seems sufficiently similar to y, that somehow you recall it).
And thus have what counts as a mental representation of that sensation. Not as a disembodied feeling, but rather as one thoroughly embedded in (the recollection of) a “real-world” event. You then compare the current sensation (x ) with the mental representation of y, and attempt to discern if they’re the same, or different, and if so, by how much, etc. Through some kind of a cognitive process.
etc. Each f is dynamic (as for that matter are both sets of f ), presenting themselves with varying degrees of force and vivacity, in a manner not unlike the way Hume distinguishes impressions from ideas in the opening paragraphs of A Treatise on Human Nature.
How might this work in practice? Hold out your finger and stick a pin into it. You experience a sensation comprising a certain feature-set, i.e., the sensation is sharp, it is persistent, it may be accompanied by the extrusion of blood, there is swelling, it is localized to the point where you inserted the pin, etc. Being the inquisitive sort, you wonder, just what that sensation is. So you call up the last time you stuck a pin in your finger, circumspectively analyze the feature-set, and conclude it is similar (or, at least, “close enough”).
What would Wittgenstein’s response be to this experiment? He probably wouldn’t have much to say. As he observes at §285, we can’t experience somebody else’s sensations. “Another person can’t have my pains,” §253, because, obviously, they’re not me.
But he then abandons this promising observation in order to pursue two other issues, although he doesn’t clearly distinguish between them. These are: (a) “Knowing that” one has a sensation, such as pain. Here, he says: “It can’t be said of me at all … that I know I am in pain” (§246). If you “knew” you had pain, then you could “doubt” if you had pain, which can be solved by pricking your finger with a pin, as at §288. This simply is “pain,” not “knowledge of” pain.
And, (b) characterizing a sensation, including how it gets named, how we know what other people are saying when they use the word for it, etc. For example, if one says one doubts if one is in pain, we think he doesn’t know the meaning of the word “pain,” §288. “What does that mean [when I say ‘I am in pain’]? Does it mean: ‘If someone else could know what I am calling “pain,” he would admit that I was using the word correctly?’” (§289).
Language is communal. Therefore, in order to communicate, you must be able to tell whether your sensation is the same type of sensation as that experienced by everybody else. If sensations were private mental experiences, then in order to do so, we would have to “extrapolate it from our own case” and assume everybody else feels the same way. This, however, is implausible. “If one has to imagine someone else’s pain on the model of one’s own, this is none too easy a thing to do: for I have to imagine pain which I do not feel on the model of the pain which I do feel,” §302.
I think Wittgenstein goes too far here. He is right that pain is not a “private object before the mind” and that what counts as pain is not learned by means of an “inner ostensive definition.” As revealed by the futility of our earlier attempt to parse a correspondence theory of sensation, sensations cannot be treated “as if their criterion of identity were very like the criterion of identity of material objects.” He also is right that we don’t engage in a cognitive process of self-introspection, somewhat like that I characterized above, at least while the sensation is happening. Rather, we just are experiencing the sensation, in all of its non-feature set, non-predicative fulsomeness.
However, he is wrong, if he means there never are occasions when we engage in this form of circumspective analysis – though it occurs with reference to specific, remembered incidents, and not some abstract concept. Furthermore, he is wrong if he thinks that just because the use of the word is connected with observable behavior, he somehow has done away with the sensation itself. The sensation is far more than the grammar of its concept, or a grammatical problem. It isn’t some linguistic fiction. Rather, it actually exists.
Here’s an example of just such circumspection at work and in actual practice. I recently went and got my eyes checked, and underwent an examination of the sort an opthamologist typically administers to a patient who needs for glasses (which I do) (yet again). The patient peers into a complex piece of equipment fitted with different lenses, while staring at a chart upon which are printed letters and numbers of different sizes. The opthamologist asks the patient, “What is the smallest line you can see?” or something to such effect, and the patient responds. The opthamologist then flips over a different strength of lens, and the patient is invited to respond to the question, “Is that better? Is that worse?” If the patient isn’t sure, then the opthamologist repeats the exercise. The patient says, “Yes, A is clearer than B,” or vice versa.
In other words, the patient has engaged in a cognitive process, and reached a conclusion of the sort that might be expressed by the phrase, “I know that …”. The patient accomplishes this outcome by comparing the feature-set of incoming sensations (the letters are crisp, the letters are blurry, that’s an “R” and not a “K,” etc.) with the feature-set of the remembered mental representation (the way the alpha-numeric characters appeared when viewed through the previous lens). The patient has to be “referring” to a “mental representation” (or at least engaging in some form of a cognitive process with respect to it), for the simple reason that the previous image no longer physically is present.
The reason why Wittgenstein’s view is wrong, is because of course we experience pain as a phenomenon, even though we might not know what to call it. To continue with the doctor example, the patient isn’t concerned with “naming” what the sensation is, or establishing criteria for the correct application (use) of that identifier. Rather, the patient simply is participating in a process to enable the doctor to evaluate the patient’s condition. The doctor may, but need not, disclose a diagnosis to the patient. The doctor may not arrive at a diagnosis immediately; a variety of observations first might have to be accumulated, the doctor ventures a hypothesis, looks to refute it, confirms it, etc. That is, a word or phrase – a descriptor – probably isn’t assigned to this collection of observations, until some point in the diagnostic process, subsequent to its onset.
Non-conclusionary patient self-reports (i.e., “Where does it hurt?” “It hurts here.”) are an important element the doctor considers, in addition to the doctor’s own clinical observations. It would not be possible for the patient to make these reports, unless the patient in fact was experiencing an underlying symptom. In fact, come to think of it, the entire medical discipline of psychiatry relies almost completely upon patient self-reports.
(1) Functional behavior, that is, the ability to use language, follow rules, manipulate equipment, and the like. These are important to Wittgenstein, because of his theory that actual sensations simply collapse into sensation-experiencing behavior (the type of behavior exhibited by someone experiencing a sensation).
(a) Attention – vigilance: the ability to focus awareness to a specific stimulus in the environment, and to respond to that stimulus.
(b) Speed of processing: the amount of time needed to complete a simple cognitive task, which often includes encoding information, making a decision, then formulating and executing a response (functional behavior).
(c) Working memory: short-term maintenance and manipulation of information, such as in the opthamologist example.
(d) Executive functioning: scheduling processes or task management.
(e) Declarative memory: the explicit recall of previously-learned information; the ability to encode, store and retrieve information from long-term memory.
(f) Reasoning: higher-level cognitive processes which involve complex strategic planning and information-processing skills.
Wittgenstein has nothing to say about any of these phenomena, except to deny they exist. We do not “know” we are having a sensation, we simply have it.
(3) Sensations, which often may be comorbid with cognitive processes. These run the gamut from sublime feelings of happiness or contentment to extremes such as auditory or visual hallucinations. Like I said earlier, Wittgenstein seems to deny these exist. Or, if and to the extent they exist, basically they are irrelevant, because they are manifested in behavior, and there’s nothing more that can be said about them.
(4) Actual brain activity. For example, functional MRI can detect when the dorsal-lateral pre-frontal cortex becomes saturated with oxygenated hemoglobin. This in turn sets up a pattern of activity across the entire brain. Dorsal-lateral hyper-frontality (the hemoglobin is or becomes too deoxygenated, therefore the brain circuits abnormalize) may be caused by asynchronous firing of neurons; which in turn may be caused by low levels of dopamine or norepenephrin. This condition often correlates with the behavioral symptoms to which we have assigned the word “schizophrenia.” It can be moderated with psychotropic medications such as modafinil, which tend to reverse the entire cycle I just have described. Wittgenstein has nothing at all to say about the brain.
Parsing these distinctions through Wittgenstein interestingly illuminates where he’s onto something and where he’s barking up the wrong tree, figuratively speaking.
 Wittgenstein, L., Tractatus Logico-Philosophicus 151 (1961).
 Govier, T., “Variations on Force and Vivacity in Hume,” The Philosophical Quarterly 44 (Jan. 1972); Landy, D., “Humes Impression/Idea Distinction,” 32 Hume Studies 119 (Apr. 2006).
 Temkin, J., “Wittgenstein on Epistemic Privacy,” 31 The Philosophical Quarterly 97 (Apr. 1981).
 Fogelin, R., Wittgenstein 170 (2nd ed. 1987).
 Kripke, S., Wittgenstein on Rules and Private Language 115 (1982).
 Pears, D., Ludwig Wittgenstein 151 (1986 ed.).
 Pears, D., Ludwig Wittgenstein 154 (1970 ed.).
 Brenner, W., Wittgenstein’s Philosophical Investigations 43 (1999).
 Ayer, A., Wittgenstein 77 (1985).
 Kenny, A., Wittgenstein 182 (1973).
 McGinn, M., Wittgenstein and the Philosophical Investigations 121 (1997). Ayer calls it a “private ostensive definition,” Ayer, A., Wittgenstein 80 (1985).
 Pears, D., Ludwig Wittgenstein 150 (1970 ed.). Might we not, with Quine, simply state that such propositions are referentially opaque? Quine, W., Word & Object 141 (1960).
 I read §296 as originating with Wittgenstein’s sarcastic interlocutor, so it doesn’t count. Also – why does he use an exclamation point here? It comes off as though he’s some kind of a child making an exciting discovery.
 A. J. Ayer (of all people) comes to Wittgenstein’s defense. “Wittgenstein did not deny that we have sense-experiences, including sensations of pain and feelings of movement, or that these experiences are private in at least one reputable sense of the term. He may have imagined situations in which one would have a ground for saying that different persons shared their thoughts or sensations, but in the normal way he allowed each of us to have his own. Neither did he advance the view that a man’s sensations and feelings, let alone his thoughts and images, are identical with physical events. He did not maintain that it is only if they are interpreted in physical terms, whether as referring to physiological states, or to dispositions to overt behavior, that statements about one person’s experiences can be made intelligible to another.” Ayer, A., Wittgenstein 74 (1985).
 Ayer, A., Wittgenstein 109 (1985).
 E.g., if the patient is unconscious and a bone is sticking out of the patient’s arm, then the doctor confidently might diagnose the patient has a broken arm, without soliciting patient input. Or, the patient might have no idea of what’s going on, due to lack of specialized knowledge, cognitive impairment, absence of insight, or for any number of other reasons.
 The use of this kind of introspective evidence in cognitive science is the subject of considerable academic debate, as it should be; see, e.g., Jack, A. & Roepstorff, A. (eds.), Trusting the Subject? (2003). One volume wasn’t enough, so they put out another one with more essays, in 2004.
 This taxonomy is not original with me; see, e.g., Green, M., “Cognitive Impairment and Functional Outcome in Schizophrenia and Bipolar Disorder,” 67 J. Clin. Psychiatry 3 (2006).

References: §285
 §253
 §288
 §288
 §302
 §296