Stephen Lumsden: Qualia in philosophical discussion

Define a ‘quale’, giving some examples of qualia. What is the philosophical interest of the notion of a quale?

Qualia can be briefly summarised as the subjective qualitative experience of an individual in their interaction with the outside world. Its singular, quale, would refer to to a single instance of such an experience, namely the experience one would have in, for instance, tasting coffee or seeing the colour red. The significance of the notion qualia is debatable though and for this reason such a brief summary will not suffice to give us a real idea of what qualia entail. In this essay we will focus on the colour red and the sense of taste through some thought experiments in an attempt to investigate what qualia mean to us. We can then question whether qualia do represent additional knowledge, is the actual notion of qualia really something in itself, whether qualia may vary between people and what relevance qualia has in the area of consciousness.

The main areas of qualia relate to one’s perception of colour, taste, smell, touch and sound. In this regard they can relate closely to the five senses. Senses such as sight will help us detect something, but qualia will usually add something more mysterious to the individual’s experience. For instance when we see red we feel we really experience this colour rather than merely recognising it or distinguishing it from others. As opposed to a blind person armed with a spectrometer, which can detect red by its wavelength corresponding to 650 nm, we are, in the process of seeing the colour, acquiring something extra in the process. This can be described as its phenomenal character. Likewise when we drink coffee or beer its taste will mean something to us which we find difficult to put into words. We may be able to explain this subjective experience in our own words, but such explanation will never be fully coherent with that of the evaluations of others. There will be no common objective means of explaining such phenomena. This problem is referred to as the explanatory gap. The problem of the explanatory gap will pose problems for the physicalist and may help the dualist’s argument. The physicalist will fail to see any direct connection between qualia and a direct corresponding process in the brain while the dualist will point to this ineffable qualitative subjective as something intrinsic to the separateness of the immaterial mind.

Some philosophers question whether the qualia add to human knowledge and Frank Jackson posits the thought experiment of Mary who has lived in a black and white room. Her skin has been shaded grey and she has never seen any colours other than shades of monochrome. She has learnt, via academic study, everything about colour from a scientific perspective. Then comes the day when she can finally leave her room and experience the outside world with all its various colours and sensations. Will she learn anything new in seeing colours apart from what she already knows? When she sees a red rose will her newly added experience really add to her knowledge of what she already has learned about red, or will she just somehow re-affirm her factual knowledge from a different perspective? The same thing can be said about observing the heat of water boiling or merely expressing the rising temperature of it from

gauging its increased molecular activity. If Mary does experience something extra which cannot be explained by her pre-existing knowledge of the physical attribute of red, then her new experience cannot be explained by physicalism, and this may imply that something immaterial is at work.

Daniel Dennett challenges the significance of the notion of qualia and proposes the thought experiment of Chase and Sanborn. The pair are coffee tasters for Nescafe. Both do not like the coffee any more, but for different reasons. Mr Chase insists the qualia associated with coffee has remained the same, but his tastes have changed while Sanborn counters that that his tastes are the same, but the coffee’s qualia have changed. Who is correct? Dennett also asks about beer. Remember when you first tasted beer and thought the taste revolting? Gradually most people will acquire a fondness for it though. One is again asked whether it is the qualia that changes or ones own tastes? Our memory of the initial subjective experience could be in question or do we have to account for our preferences changing over time? We cannot be certain about either, but one is forced to question whether the whole idea of qualia just represents a different perspective in judging sense data and may not exist as something separate in itself.

In addition to the explanatory gap we do not know whether we experience the same qualia as each other. John Locke proposes the thought experiment of the inverted spectrum and posits the idea that I could be experiencing the colour red for someone else’s idea of green and vice versa. We may never know, but our behaviour is the same. Hence our sense of qualia could be a subjective learned experience. Tests on colour blindness can usually detect sufferers through tests for its different forms. However the psychologist Stephen Palmer proposes that some people (reverse trichromats) may be undetectable and that the inverted spectrum may be a reality for some. If this is true, such evidence tells us that qualia cannot be explained in behaviourist or functionalist terms alone. Behaviourism will fail to explain this, as we have to accept that different inputs (namely the different experiences of of red vs green) do not appear to cause any discernibly different results that we can detect, while functionalism is left in the dark due to a lack of traceability in the process. This possibility cannot be explained by the dualist either, whose separate immaterial mind should be able to detect the qualia differences. There has to be something additional at work, because it cannot be explained purely in terms of any of the approaches above.

In concluding we are left with a feeling of just how little we know about qualia. Jackson’s thought experiment may have us believe there are ways around having the subjective qualitative experience. Knowledge alone could suffice. Dennett asks whether such differences do make a difference. Locke asks us whether our idea of qualia may be just a learned experience. I would agree most with Locke. Going back to the thought experiment of Mary I do not believe one of the first things she says as she enter the real world is “So that’s what the colour of red looks like.” (as some philosophical literature would have us believe). She will say “Where is my spectrometer. I want to check that rose is red.”. Such is the effect of experience and habit on the acquisition of knowledge, whether new or not. One must, though, recognise qualia as a unique experience which asks questions about consciousness and personhood.


An Essay Concerning Human Understanding (Hacket classics), John Locke, edited by Kenneth P. Winkle, 1996

Philosophy of Mind: Brains, Consciousness, and Thinking Machines (The Teaching Company), Patrick Grim, 2008

Stanford Encyclopedia, entry on Qualia, Michal Tye, 2017

© Stephen Lumsden 2018