Why I Worry About Phenomenal Realism

Phenomenal realism and phenomenal irrealism are two philosophical views about consciousness. The former view says that there are things we know about our own experiences, from a first-person perspective, that cannot be known from a third-person perspective. The point has been illustrated with some famous thought experiments — examples include Mary’s Room and Philosophical Zombies. I’m a phenomenal realist, but I often worry that it’s false, and this post is an attempt to explain why I’m worried. But first, here’s my preferred thought experiment for illustrating the point of phenomenal realism:

Alien Researchers: suppose some aliens are studying humans from space, trying to figure out what makes us tick. With their advanced alien science, they are able to study human brains down to the last neuron, and peer through all of human history. They know how human brains work, they know how humans behave, they know how humans use language to communicate. These aliens are perfect scientific researchers of humankind — so much so that they know, or can easily find out, everything about humans that can be known from a third-person perspective.

Knowing all this, would the aliens know about human experiences in the same way that we do, from the first-person perspective? Would they know what it’s like to be a human being that sees, hears, smells, tastes, and feels the world in the way that humans do? Or is there a difference between third-person knowledge of humans, and first-person knowledge of human experience?

A phenomenal realist says that there is a difference between third-person knowledge and first-person knowledge, so the aliens might not know everything that we know about our own experiences. The aliens might experience the world very differently than us (they might have different senses, for example) and if so then no amount of studying humankind from the third-person perspective will let them know what it’s like to experience the world in the way that we do. Third-person knowledge of human brains, human culture, and human language isn’t enough to know what it’s like to have human experiences.

A phenomenal irrealist, in contrast, says that the aliens would know everything that we know about our own experiences. With their complete scientific knowledge of human brains, culture, language, etc., they would ipso facto know everything that there is to know about human experiences. Whatever it is that we know about human experiences from the first person, this knowledge is nothing over and above some knowledge that the aliens could attain from the third person. So the aliens’ third-person knowledge would leave nothing out.

For myself, I am a phenomenal realist. It seems obvious (to me) that there is a difference between first-person knowledge of experience, and third-person knowledge of biology, cognitive science, language, etc. Knowing what it’s like to see colors and hear music isn’t literally the same thing as knowing some collection of facts about biology, cognitive science, and/or language. These judgments aren’t based on some further argument — they just seem obvious (to me!). Arguments have to end somewhere, so I’m not worried by the mere fact that I don’t have further arguments for my pro-realism judgments. But I do often worry that I’m wrong about phenomenal realism — not so much because I’m convinced by the arguments against it, but simply because plenty of reasonable, thoughtful, and well-informed people don’t share my judgments.

The line of thought that worries me goes something like this:

P1) If phenomenal realism is as obviously plausible as I think it is, then the vast majority of reasonable, thoughtful, and well-informed people should find it obviously plausible.

P2) It’s not the case that the vast majority of reasonable, thoughtful, and well-informed people find phenomenal realism obviously plausible.

P3) If phenomenal realism isn’t as obviously plausible as I think it is, then I should doubt it.

C) I should doubt phenomenal realism.

You might think that this sort of argument would have just as much force if it were applied to any contentious topic in philosophy. Couldn’t we replace “phenomenal realism” with “moral realism” — another thesis that strikes many but not all as obviously plausible — and get just as forceful an argument against moral realism? But I don’t think so. I think phenomenal realism is especially vulnerable to this kind of argument, because P1 and P3 are more plausible as claims about phenomenal realism than they are as claims about moral realism (for example). This is because (1) phenomenal realism seems so obviously plausible (to me, and, I think, to most other phenomenal realists) and (2) because it has so little going for it apart from its obviousness.

Start with the first point and P1. There are lots of claims in philosophy that strike me as being in some sense obviously plausible. For example, it seems highly plausible that it’s wrong to torture people for fun. But I can get myself in the headspace of the moral anti-realist, according to whom nothing is right or wrong, in which case it’s not wrong to torture people for fun. I can at least wrap my head around that view; I can put myself in the perspective of someone who accepts it. So it seems obvious to me that some things are morally wrong, but not so obvious that I should expect everyone to find it obvious. P1 wouldn’t be so plausible if it were a claim about moral realism. More generally, there are lots and lots of philosophical views that seem obvious to me, but not so obvious that I can’t get myself in the headspace of someone who denies them.

But phenomenal realism seems different. I don’t merely find it plausible; I struggle to get myself in the headspace of those who deny phenomenal realism. If we deny phenomenal realism, then we accept that a total achromat could learn what it’s like to experience colors by amassing vast third-personal knowledge on the brains and behavior of color-sighted people. This could be because (i) there is nothing to be known about “what it’s like to experience colors,” so the scientific or third-personal knowledge is the only knowledge to be bad, or it could be because (ii) vast third-person knowledge of brains and behavior somehow “adds up” to first-person knowledge of color experience. I struggle to wrap my head around both views. With respect to (i), it’s very hard for me to doubt that I know something about color experience from my first-person perspective as a color-sighted person. And with respect to (ii), this seems to me almost like saying that we could learn what it’s like to see red by simply counting to a very very very high number. The kinds of knowledge at issue are just different, and we shouldn’t expect for one kind of knowledge — even a lot of it! — to “add up to” the other kind. So I find it hard to occupy the perspective of someone who denies phenomenal realism, in a way that I don’t find it hard to occupy the perspective of someone who denies moral realism. But if phenomenal realism is so very obviously plausible, then it’s reasonable to expect other people to find it obvious. P1 is, I think, plausible.

Then there is the second point: I have no good reason to accept phenomenal realism apart from the fact that (I think) it is obviously plausible, so if it turns out to not be obviously plausible, then I should have serious doubts about it. Here is what I have in mind. The philosophical claims I accept can be roughly and crudely sorted into two camps: the claims I accept because they are independently plausible, and the claims I accept because although they are not independently plausible, they are parts of theories that have greater independent plausibility than their alternatives.

Here’s an example of a claim in the second camp: if someone took great pleasure in counting blades of grass, then it would be very good for them to count blades of grass. I don’t think that claim is all that plausible. I don’t think it’s deeply implausible, either, though many disagree with me about that. But I accept it, because I accept the broad idea that what is good for us is determined by what we really want, or what we take pleasure in doing. I think this broad idea is plausible enough that it leads me to accept some other claims, like the claim about the grass-counter, that I probably wouldn’t otherwise accept.

Phenomenal realism is not like that. Phenomenal realism is firmly in the first camp: I accept it not because it’s a part of some other theory that is independently plausible, but because it itself is independently plausible — or so I believe. Phenomenal realism is indeed a part of various theories — dualism, Russellian monism, non-reductive physicalism — but much of these theories’ plausibility comes from phenomenal realism, not vice versa. To that extent, they are not plausible in a way that is independent of phenomenal realism. So while I think that each of these theories is at least somewhat plausible, I think this because I accept phenomenal realism.

Take dualism, for example: the view that experience is distinct from the physical. If one denies phenomenal realism — if one believes that everything about experience can be known from the standpoint of third-person empirical science — then it would be quite odd to embrace dualism. One should instead say that the facts of experience are nothing more than the facts investigated by empirical science (facts of biology, cognitive science, language, etc.) and this is why knowledge of the latter suffices for knowledge of the former. Few if any people argue from dualism to phenomenal realism. Rather they argue from phenomenal realism to dualism. Phenomenal realism isn’t supported by other theories; rather it supports them. I accept it because (I think) it’s obviously plausible, not because it receives support from something else. If it turns out to not be obviously plausible, then I’m left with no good reason to go on accepting it. This is why I think P3 is plausible, whereas the corresponding claim about grass-counting (for example) would not be.

In fact I would go further, and say that I have good reason to reject phenomenal realism — if only it weren’t so plausible. I say I have good reason to reject it because it is inconsistent with a view that I otherwise find appealing: an unapologetically reductive physicalism, according to which absolutely everything in the universe is made up of physical stuff, and everything there is to know about the universe can be known in purely physical terms. That’s an extremely rough sketch, but you get the idea. It’s a highly parsimonious and unified vision of the universe — everything is physical, and the book of the world can be written in the language of physics with nothing left out. This highly unified picture is inconsistent with phenomenal realism, and if I didn’t find phenomenal realism so plausible, I’d at least be very tempted to accept it. So if phenomenal realism turned out to not be so plausible after all, I’d take myself to not only have no good reason to accept it but also good reason to reject it. In my case, at least, P3 is extremely plausible.

So there you have it. Few claims in philosophy seem to me as intuitively compelling as phenomenal realism. When I’m not worrying about peer disagreement, I regard it in more or less the same way as I regard the claim that there are no red numbers. But in a strange way, the fact that realism seems so compelling also leads me to doubt it. If it’s as intuitively compelling as I think, then there should be consensus (as there is, presumably, on the claim that there are no red numbers). And although it seems there are more phenomenal realists than irrealists, there is nothing like consensus. So maybe phenomenal realism isn’t so obvious after all, in which case I’m left with no good reason to accept it.

This argument, more than any argument I’ve seen in print, is what makes me nervous about phenomenal realism. In fairness, I haven’t said anything about the actual arguments that are in print, and others may feel very differently. But I wonder whether other realists feel the same way as me.