Seeing Qualitons as QualiaA Dialogue with Wittgenstein on Private Experience, Sense Data and the Ontology of Mind
Seeing Qualitons as Qualia
A Dialogue with Wittgenstein on Private Experience, Sense Data and the Ontology of Mind


In this paper we put forward the thesis that qualia are tropes (or qualitons), and not (universal) properties. Further, we maintain that Wittgenstein hints in this direction. We also find in Wittgenstein elements of an account of language acquisition that takes the presence of qualia as an enabling condition. We conclude by pointing out some difficulties of this view.

Table of contents

    In section 304 of the Investigations (1973), Wittgenstein responds to his interlocutor who asks him “But you will surely admit that there is a difference between pain-behaviour accompanied by pain and pain-behaviour without any pain? (…) And yet you again and again reach the conclusion that the sensation itself is a nothing”. The charge is that our basic qualitative sensory states such as the ones present when we have pain are irrelevant and can be dismissed – it is as if they were not present. One could read Wittgenstein’s interlocutor to be pressing him to endorse the denial of qualia. “Qualia” is a frequently used expression to refer to basic qualitative sensory states. Wittgenstein, however, responds that it is as if they were not present, but still there is something present. He writes: “Not at all. It is not a something, but it is not a nothing either! The conclusion was only that a nothing would serve just as well as a something about which nothing can be said.” Wittgenstein then refuses the charge of denying qualia. He is rather hinting at a way to understand qualia. Or so we argue in this work.

    We believe Wittgenstein considers qualia to be something like tropes. Tropes are abstract particulars1. The friend of tropes shares the nominalist dislike of universals (and, typically, of properties). There could be one-place or many-places tropes; the former are sometimes called qualitons and the latter relatons. Instead of properties, trope theory takes every predication to involve particularity; 'x is a book' doesn’t predicate the same property as ‘y is a book’ – our predicate ‘book’ does no more than point at some relevant similarity between x and y; it names no property. The green of a leaf of grass is not the same as the green of another leaf – only they can be relevantly similar, similar enough to be under the same predication.

    We hold that qualia can be seen as qualitons, and not as (universal) properties of a mental state (such as pain, for example). Further, we are convinced that Wittgenstein hints in this direction. Hacker’s comments (1993) on section 304 of the Investigations suggest that what Wittgenstein "is doing is rejecting the grammar of name and object". Having a pain is not like to having a penny. So, pain is not concrete. Also, it does not make sense to say that we have now the same pain we have had yesterday. So, pain is not a universal. These together suggest that pain is an abstract particular. At the same time, a sensation is not a nothing, as it’s not the absence of anything. It is nothing only in the sense that it cannot be used unaided in predications. We will try to make this clearer and elaborate further on the view by considering bits of his Lecture notes on “Private experience” and “Sense data” (1968).

    Wittgenstein writes:

    “What if someone asked: "How do I know that what I call seeing red isn’t an entirely different experience every time?”” (p. 279).

    The friends of tropes would then reply: Why do we need them to be the same? Isn’t enough that we use the same word for what is red? Red doesn’t need to be the name of a sensation.

    And Wittgenstein:

    “We say here that a name is given to a particular impression. And this is strange and puzzling. For it seems as though the impression were too ethereal to be named (Marrying a woman’s wealth).” (p. 275).

    It sort of escapes us until we grab it with a concept. It is as if there is nothing to be known until we find the resources to express it. In order for me to know I have a pain I need to speak English, otherwise I don’t know what to do with the particular sensation I have. When I learn a language, I learn to use my qualiton as a qualitative indication of me having a pain or me sensing something red. Such a qualitative indication works only when I am familiar with the rules that govern the use of ‘red’ or ‘pain’ in English.

    “What could be meant by: truthfully calling a color impression ‘red’? Does the word fit one impression better than another?” (p. 295). Further, “[i]f I say ‘I see red’ without reason, how can I distinguish between saying it with truth and saying it as a lie?” (p. 294). 

    The expression of an impression is only true or false with respect to rules for concepts, with respect to usage in a public language. If there is no independent stance of judgment, my expression that I see red can always be a lie. It’s me alone with my qualiton. A trope, seen as a quale, is private. There is nothing in a trope that makes it fit a word better than any other. Tropes have no name – they are particulars, they are re-identified only when they are clustered together by our sensory vocabulary. Sensations are red or green, qualia (as qualitons) could be anything provided that we acquire the relevant concepts and, with them, the relevant patterns of similarity.

    “But we are under the impression that we can point to the pain, as it were unseen by the other person, and name it.” (p. 276)

    We can point at the pain, but not at the qualiton. When we point at the pain, we are pointing and naming a state that is identified through different indicators. The trope is the subjective and qualitative indicator. The same trope could indicate something very different. Qualia are enabling conditions for concept acquisition; a given qualiton is neither sufficient nor necessary for any concept to be acquired. What we mean with our words for sensations is not something of our own. Only the qualiton is private, but we don’t talk about it.

    “The difficulty is that we feel we have said something about the nature of pain when we say that one person can't have another person’s pain.” (p. 277)

    We assume every pain is associated with a sensation – with a quale. Without qualia, we would hesitate to call it a pain. Yet, we can be easily fooled by pain-behaviour. As you wrote in the Investigations (257), we could not learn what is meant by pain by attending solely to our qualia.

    “Now whom shall we call blind? What is our criterion for blindness? A certain kind of behaviour. And if the person behaves in that particular way, we not only call him blind but teach him to call himself blind. And in this sense his behavior also determines the meaning of blindness for him. But now you will say: “surely blindness isn’t a behavior; it's clear that a man can behave like a blind man and not be blind. Therefore 'blindness' means something different; his behavior only helps him to understand what we mean by ‘blindness.’ The outward circumstances are what both he and we know. Whenever he behaves in a certain way, we say that he sees nothing; but he notices that a certain private experience of his coincides with all these cases and so concludes that we mean this experience of his by saying that he sees nothing." (p. 285)

    Yes, a blind person is detected through behavior. The qualitons of a blind person could not be suitably exploited to provide the behavior we would identify as seeing. Of course there is a physiological counterpart to blindness, but the physiological tests are designed to make sense of our common sense idea of what is blindness.2 We assume also that there is a quale associated to blindness even if we cannot access it. We are constantly under the impression that we are naming brute sensations and not a complex of sensations and behaviors when we use expressions like blindness (or color-blindness, or red-blindness).

    “As it were: There is something further about it, only you can't say it; you can only make the general statement. It is this idea which plays hell with us.” (p. 276)

    Indeed, we feel compelled to say that there is a quale (a qualiton) corresponding to each occurrence of, say, pain. We talk of pain in general, but there is a particular indicator of pain in each case – and we learn to see them as relevantly similar. We exploit the qualitons available to us when we are learning our sensory vocabulary.

    I wonder “[h]ow can we point to the color and not to the shape? Or to the feeling of toothache and not to the tooth, etc?” (p. 276)

    That reminds me of a case Noodhof (1998) considers. A glass is shattered as a result of a soprano singing a note. It seems tempting to say that it is the pitch and not the meaning of the singing that caused the shattering. Similarly, my feeling of pain (and not the activation of my C-fibers) is what makes me scream. It is in virtue of the pain that I scream. Gozzano (2008), for one, holds that tropes ought to be simples, that is, they must be maximally determinate. If this is so, there should be a pitch-trope and a meaning-trope. Similarly, when considering a causal process that could lead to the acquisition of two different concepts (say, tooth and toothache), one should posit two and not just one quale. The claim is that if a trope is a simple, it cannot carry two causal powers. Robb (1997), on the other hand, holds that causal powers are connected to particulars – it is a particular trope that causes the (particular) shattering of the glass. While it could be that it is better to describe the trope as having a high pitch – each trope has several similarity relations with other tropes – it is the trope qua trope that causes the shattering. Similarly, it is the trope qua trope that is part of the causal story we want to tell about learning the concept of toothache. Of course, in this case we have troubles individuating qualitons. However, the relevant causal powers are to be found not only in qualia but also on the language learning context around the process. If this is so, a single trope can be part of causal processes of concept acquisition for several different concepts. Qualitons can even have relations of similarity among them independently of their role in our vocabulary learning, but these relations play no role in our capacity to identify sensations. Learning a language involves learning a way to exploit our qualia.

    We propose to see qualia as abstract particulars, to be exploited in our process of language acquisition. In that process, we cluster qualia together when we learn similarity relations. Our view is therefore one where similarity relations are crucial for the acquisition of concepts. One could, however, fear that judgments of similarity cannot get off the ground if all they have to start out with are mere abstract particulars. Suppose one is learning a sensory concept like ‘red’ or ‘bitter’ and has to acquire the relevant similarity relations among her qualia. If one has the quale Q and is taught that it resembles quale R, but not quale P, how could one compare those qualia without having them somehow present in the mind? In other words, how can my past qualia be retrieved when I need them in order to learn similarity relations if they are not (from the beginning) available in a conceptual format? The question resembles the one Wittgenstein poses at section 342 at the Investigations (1973): how can a deaf-mute person recall thoughts she had before she was introduced to any language, written or otherwise? This is a troublesome area, but we believe we can sketch a way out.

    Consider one’s attention to quale Q. We assume attention is somehow different from predication – I can attend to Q without making a predication of the sort ‘Q is φ’ (note that the abstract particular is the subject of the possible predication). If I can attend to Q, then we can have it present to the mind, at least sometimes, together with P or R. Notice that this procedure of attention can be thoroughly private and subjective – as it can differ completely from one to another person. Still, we believe this privacy is both enough to make sure that qualia as qualitons are useful for concept acquisition and does not violate the kernel of the assault on the given. All that is required is that we can manage to attend to two qualitons at the same time so that we can start to grasp the notions of similarity and relevant difference. This should be eventually enough to get the process off the ground – a process of gradual refinement of concepts so that what is roughly red eventually gets refined into different shades of red.

    We would like to finish in a less heroic tone. We assume that we can attend to more than one qualiton at a time (and register similarities in a rudimentary way) independently of our introduction to a public language. We take this to be a plausible assumption. If we are not entitled to make this assumption, maybe the account of qualia as abstract particulars loses some of its attraction. In any case, there is an interesting lesson to be learned: any talk of qualia that ascribes to them an explanatory role comes together with some commitments concerning privacy.


    1. Campbell, K. (1990). Abstract Particulars. Oxford: Basil Blackwell.
    2. Gozzano, S. (2008). “Tropes’ simplicity and mental causation”, in: Gozano & Orilia (2008), 133-154.
    3. Gozzano, S. & Orilia, F., eds. (2008). Tropes, Universals and the Philosophy of Mind, Frankfurt: Ontos-Verlag.
    4. Hacker, P. M. S. (1993). Wittgenstein: Meaning and Mind, Volume 3 of an Analytical Commentary on the Philosophical Investigations, Part II: Exegesis 243-42. Wiley Blackwell.
    5. Nordhoof, P. (1998). “Do tropes resolve the problem of mental causation?”, The Philosophical Quarterly, 48, 221-226.
    6. Robb, J. (1997). “The problems of mental causation”, Philosophical Quarterly, 47, 178-194.
    7. Sacks, O. (1996). An anthropologist on Mars: Seven paradoxical tales. New York: Vintage Books.  
    8. Williams, D. C., 1953. “The Elements of Being,” Review of Metaphysics 7: 3-18, 171-192; cited from Principles of Empirical Realism, Springfield: Charles C Thomas 1966: 74-109.
    9. Wittgenstein, L. (1968). “Notes for Lectures on ‘Private Experience’ and ‘Sense Data’”, The Philosophical Review, 77 (3), 275-320.
    10. Wittgenstein, L. (1973). Philosophical Investigations, Oxford, Blackwell.
    Williams (1953) and Campbell (1990) are seminal articles on tropes.
    Cf. Sacks (1996) on cases of blindsight.
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