Kammerer on acquaintance and certainty
Many experiences have phenomenal properties: there is something it is like to have them. A puzzling fact about these properties is that we appear to know about them in a special, direct fashion: we are "acquainted" with the phenomenal properties of our experiences. Another, related puzzle is that we appear to know about these properties with absolute certainty: if you have an experience as of looking at a red wall, you can conclusively rule out the possibility that you have an experience as of looking at a green wall.
In Schwarz (2018), I put forward a tentative explanation of these facts. I argued that it would be useful for an agent in a world like ours to have a credence function defined over a space that includes special "imaginary" propositions that are causally tied to stimulations of their sense organs in such a way that any given stimulation makes the agent certain of a corresponding imaginary proposition. What we conceptualise as propositions about phenomenal properties (of our experience), I argued, might be such imaginary propositions.
Kammerer (2021) argues that my model is inadequate because it predicts a kind of certainty that we don't actually have. He offers three kinds of counterexamples.
First, people are sometimes mistaken about what they feel: a sudden cold sensation, for example, can be mistaken for pain.
Second, people mistakenly believe that their visual field is more detailed than it is.
Third, some people hold that there are no phenomenal experiences at all.
Let's start with the third. Presumably the idea is that if we are certain that we have a particular phenomenal experience X then we couldn't coherently believe that we have no phenomenal experiences at all. But it's not part of my model that the imaginary propositions of which the agent becomes certain are conceptualised as "phenomenal experiences". If you ask an eliminativist or illusionist what they mean by 'phenomenal experience', they will give you an answer. They deny that we have experiences with such-and-such definitional properties. This theoretical claim is orthogonal to any imaginary proposition. I don't see a problem here.
How are the first two cases meant to go? The idea is that if we know that we can be mistaken about the phenomenal properties of our current experiences then we can't be certain about these properties.
Can we be mistaken about the phenomenal properties of our current experiences? Arguably, yes. But we should distinguish different kinds of mistake.
One kind of mistake concerns the classification or description of the relevant state. Suppose I mistake a cold sensation for a pain sensation. We might also consider a case in which I'm unsure (perhaps for a moment) whether I have a cold sensation or a pain sensation. What is going on here? Perhaps the case is analogous to a case in which I mistakenly classify gnocchi as a pasta dish, or in which I'm unsure about whether gnocchi are a kind of pasta, even though I know full well what gnocchi are made of, how they are eaten, etc. I'm simply wrong or unsure about how the category 'pasta' applies. This kind of case would be harmless for my proposal.
A similar kind of mistake or uncertainty can arise from the difficulty of extracting relevant information from a perceptual experience. When I'm looking at the arrangement of 14 pens on my desk, I can't immediately tell how many pens there are. I might mistakenly think there are 15, and I might be unsure about the number. I would then be similarly mistaken or unsure about my phenomenal experience, for my visual experience plausibly settles the number of pens: if the number of pens were different, I would have a different experience. Here I'm not wrong or unsure about how the category '14 pens' applies. But arguably my mistake or uncertainty still concerns the classification of the experience, rather than the experience itself.
What would uncertainty about the experience itself look like? It would mean that I can't rule out scenarios in which I have a different experience. Here is how I illustrated the relevant kind of certainty in my paper:
Our perceptual experiences do appear to convey a special kind of information that is more certain than our ordinary beliefs about the world. To illustrate, consider your present perceptual experience. Are there any possibilities you can conclusively rule out in virtue of having this experience? Don't think of this as an attitude towards a sentence. Rather, imagine different ways things could be and ask yourself whether any of them can be ruled out given your experience. For example, consider a scenario in which you are skiing – a normal skiing scenario, without systematic hallucinations, rewired brains, evil demons or the like. It could be a real situation from the past, if you ever went skiing. Your experiences in that situation are completely unlike your actual present experiences. (I trust you are not reading this paper while skiing.) In the skiing scenario, you see the snow-covered slopes ahead of you, feel the icy wind in your face, the ground passing under your skis, and so on. What is your credence that this situation is actual right now? Arguably zero. In general, when we have a given experience, it seems that we can rule out any situations in which we have a sufficiently different experience. That is why skeptical scenarios almost always hold fixed our experiences and only vary the rest of the world.
I don't know if Kammerer disagrees with any of this. It's this kind of certainty that I hope my model might explain.
I said 'sufficiently different'. The certainty intuition becomes weaker if we consider scenarios where our experiences are only slightly different. Can we conclusively rule out scenarios in which we feel, say, ever-so-slightly warmer than we actually feel? This isn't obvious. I don't think it's obviously false. But it's also not obviously true.
In conversation about these issues, an undergraduate student here at Edinburgh raised another interesting worry. Split-brain patients can have experiences in one side of their brain of which the other side is oblivious. Such a patient might reasonably say, with the left side of their brain, that they don't know if they are currently having a normal red experience – with the other half of their brain. Wouldn't they be right? If they are ignorant of their predicament, they might also mistakenly think that they are not having a normal red experience.
So perhaps there can be genuine uncertainty about current phenomenology: uncertainty about the details, or uncertainty about the parts, in a fragmented mind. The model I described in Schwarz (2018) can't explain this kind of uncertainty. But it is clear anyway that we don't conform to this model, if only because the model is computationally intractable. My real proposal is that we work somewhat like the ideal agents I have described, and that this might explain some puzzling facts about the special access we appear to have to our phenomenal states. It might explain, for example, why I think I can conclusively rule out scenarios in which I have a skiing-type experience in every fragment of my mind.
Kammerer has another objection. He argues that the "certainty model" can't explain our sense of acquaintance with the phenomenal character of experience. That I'm absolutely sure of some proposition doesn't entail that the proposition is presented to me in a direct and immediate manner.
I agree. I never said otherwise. I would hope that the model I described in Schwarz (2018) can also shed light on our sense of acquaintance. If we'd conform to my model, then stimulations of our sense organs would directly cause certainty in a corresponding imaginary proposition. We would come to be certain of something of which were previously uncertain. And we would do so without any kind of reasoning or inference. It would seem to us as if there are special kinds of facts that are directly presented or revealed to us when we have a perceptual experience.