This is the third in a series of four posts about key ideas from my book The Shadow of Consciousness; this one is about haecceity, or to coin a plainer term, thisness. There are strong links with the subject of the final post, which will be that ultimate mystery, reality.
Haecceity is my explanation for the oddity of subjective experience. A whole set of strange stories are supposed to persuade us that there is something in subjective experience which is inexpressible, outside of physics, and yet utterly vivid and undeniable. It’s about my inward experience of blue, which I can never prove is the same as yours; about what it is like to see red.
One of the best known thought experiments on this topic is the story of Mary the Colour Scientist. She has never seen colour, but knows everything there is to know about colour vision; when she sees a red rose for the first time, does she come to know something new? The presumed answer is yes: she now knows what it is like to see red things.
Another celebrated case asks whether I could have a ‘zombie’ twin, identical to me in every physical respect, who did not have these purely subjective aspects of experience – which are known as ‘qualia’, by the way. We’re allowed to be unsure whether zombie twin is possible, but expected to agree that he is at least conceivable; and that that’s enough to establish that there really is something extra going on, over and above the physics.
Most people, I think, accept that qualia do exist and do raise a problem, though some sceptics denounce the entire topic as more or less irretrievable nonsense. Qualia are certainly very odd; they have no causal effects, so nothing we say about them was caused by them: and they cannot be directly described. What we invariably have to do is refer to them by an objective counterpart: so we speak of the quale of hearing middle C, though middle C is in itself an irreproachably physical, describable thing (identifying the precisely correct physical counterpart for colour vision is actually rather complex, though I don’t think anyone denies that you can give a full physical account of colour vision).
I suggest we can draw two tentative conclusions about qualia. First, knowledge of qualia is like knowledge of riding a bike: it cannot be transferred in words. I can talk until I’m blue in the face about bike riding, and it may help a little, but in the end to get that knowledge you have to get on a bike. That’s because for bike riding it’s your muscles and some non-talking parts of your brain that need to learn about it; it’s a skill. We can’t say the same about qualia because experiencing them is not a skill we need to learn; but there is perhaps a common factor; you have to have really done it, you have to have been there.
Second, we cannot say anything about qualia except through their objective counterparts. This leaves a mystery about how many qualia there are. Is there a quale of scarlet and a quale of crimson? An indefinite number of red qualia? We can’t say, and since all hypotheses about the number of qualia are equally good, we ought to choose the least expensive under the terms of Occam’s Razor; the one with the fewest entities. It would follow from that that there is really only one universal quale; it provides the vivid liveliness while the objective aspects of the experience provide all the content.
So we have two provisional conclusions: there’s only one quale, and to know it you have to have ‘been there’, to have had real experience. I think it follows naturally from these two premises that qualia simply represent the particularity of experience; its haecceity. The aspect of experience which is not accounted for by any theory, including the theories of physics, is simply the actuality of experience. This is no discredit to theory: it is by definition about the general and the abstract and cannot possibly include the particular reality of any specific experience.
Does this help us with those two famous thought experiments? In Mary’s case it suggests that what she knows after seeing the rose is simply what a particular experience is like. That could never have been conveyed by theoretical knowledge. In the case of my zombie twin, the real turning point is when we’re asked to think whether he is conceivable; that transfers discussion to a conceptual, theoretical plane on which it is natural to suppose nothing has particularity.
Finally, I think this view explains why qualia are ineffable, why we can’t say anything directly about them. All speech is, as it were, second order: it’s about experiences, not the described experience itself. When we think of any objective aspect, we summon up the appropriate concepts and put them over in words; but when we attempt to convey the haecceity of an experience it drops out as soon as we move to a conceptual level. Description, for once, cannot capture what we want to convey.
There’s nothing in all this that suggests anything wrong or incomplete about physics; no need for any dualism or magic realm. In a lot of ways this is simply the sceptical case approached more cautiously and from a different angle. It does leave us with some mystery though: what is it for something to be particular; what is the nature of particularity? We’ve already said we can’t describe it effectively or reduce it theoretically, but surely there must be something we can do to apprehend it better? This is the problem of reality…
[Many thanks to Sergio for the kind review here. Many thanks also to the generous people who have given me good reviews on amazon.com; much appreciated!]