This post is about the philosophy of perception, what makes a philosophical debate substantive, and cognitive qualia.

Consider two views about the nature of perception and the world: on indirect realism we perceive a veil, we only indirectly get at the world through this veil. On direct realism, we perceive the world. The veil is lifted and we are in direct contact with the world.

On indirect realism what we perceive are mental objects like sense data. This is the veil that stands between us and the world. We must infer the existence of the world.

You can visualize the two views in the following ways:

indirect: perceiver => sense data => world
direct: perceiver => world

indirect: perceiver => map => territory
direct: perceiver => territory

indirect: perceiver => veil => world
direct: perceiver => world

Indirect realism gets its intuitive appeal from the idea of hallucination. If I have the experience of a red elephant in my room then I am perceiving my visual field, not a red elephant in the room. The object of my perception is the appearance of a red elephant, nothing more. We can visualize this as:

perceiver => experience of a red elephant => 

The last arrow points to nothing because there is no red elephant in the world. Here’s how the direct realist would visualize this case:

perceiver => 

The direct realist says that you don’t perceive anything when you hallucinate. You either see the territory or nothing at all.

Despite the intuitive appeal of indirect perception, the direct view is better. Using our visualization, you can get at this by stepping back and considering the question that a theory of perception should answer: what is the object of one’s perception? In the case where perception is accurate, the answer is the world. But for the indirect realist, the object of perception is a mental object, like sense data.

But how is the object of perception perceived? What is it perceived through?

On direct realism the object of perception is perceived through mental states, which we can call experience. Returning to the visualization, the `=>` is experience.

perceiver => world = perceiver experiences the world

The indirect realist cannot say this. This is because the object of perception is a mental object. Which is to say, it is experience. On this, picture one only experiences experiences. You can visualize this as follows:

indirect: perceiver => experience => world = perceiver experiences experience

Of course, there’s a sense in which you can experience experiences. I can experience an AirBnB experience. But when we say that, experience means two different things. What the indirect realist is committed to is the idea that one perceives mental states through other mental states at the same moment. This isn’t right, there’s just experience. Not experiences of experience. The mistake that the indirect realist makes is that they confuse the object of perception with the vehicle of perception, what was is aware of with how one is aware. We’re aware through experience, not just aware of things in our head.

You might be wondering what is going on in this debate. Is it substantive? Sometimes we debate things that are substantive, like whether there is a God or not. On other occasions, it seems like we are playing verbal or conceptual games.

I think this is a case where we’re playing conceptual games.

Here are two tests for whether something is a conceptual debate or not.

First the taboo test. Try to carry on the debate in other terms. If you can’t do this, there’s a good chance you’re arguing over the meaning of words or a concept. Here’s how this would look like in the God debate:

Before taboo
atheist: there is no God
theist: there is a God

atheist: there is no supernatural triomni person
theist: there is a supernatural triomni person

There's clearly a substantive debate here. Whether or not there is a supernatural triomni person is not a linguistic matter.

How does it go in the perception debate?

Before taboo
direct: the object of perception is the world
realist: the object of perceptions are mental states 

direct: mental states are not the object of awareness
indirect: mental states are the the object of awareness

This, of course, pushes the debate from perception to awareness. This may game will be played a few rounds, but it’s not clear to me how to proceed once the words like perception, awareness, contents of experience, and acquaintance are tabooed. Which is one would expect if one is only arguing over the purview of a concept. Both parties agree that we have experiences that are candidates for perception. The direct realist doesn’t deny that we can have the experience of a red elephant suddenly appearing in our rooms. What they do deny is that there would be any perception going on in that case. But it's difficult to restate this debate without using perception or its synonyms.

A shorter way to determine whether a debate is purely conceptual is to ask whether it differentiates between different ways for the concrete world to be. Consider debates over the following propositions:

1. Pluto is a planet
2. If something is a planet, then it clears its planetary orbit

If two parties are disagreeing about whether Pluto is a planet, they are likely disagreeing over whether Pluto meets the requirements for being a planet, like whether it clears the neighborhood around its orbit. The concrete world would be one way if Pluto cleared its neighborhood, it would be another way if it didn’t.

If two parties disagreed over the second proposition, then they’d be debating the requirements for being a planet. This is a conceptual matter. The concrete world would not change if the proposition were true or not.

Now, move to the debate over the nature of perception. We have two propositions:

3. Charles perceives a red elephant
4. If someone perceives X, then X is a mental state

Does the first differentiate different ways for the concrete world to be? It depends. If what perception means is having a mental state that includes the appearance of a red elephant, then yes, it does. If the proposition were true, then Charles has a mental state that includes a red elephant. If it were false, then he has a different mental state. What it would be like to be Charles would be different in the two cases.

True: Charles has a mental state that includes the appearance of a red elephant.
False: Charles has a different mental state

Likewise, if what perception means is to accurately represent the world, then this to differentiates between different ways for the concrete world to be. In one case, there is a red elephant and in another case there isn’t. The concrete world is different in both cases:

True: there’s a red elephant
False: there’s no red elephant

The debate over the nature of perception isn’t about whether there are red elephants or not. Nor is it about whether one can have the mental state that would be characterized by the appearance of a red elephant.

Instead, it’s about whether perception has as its object the world or some mental state. Which is to say it’s about propositions like this:

If someone perceives X, then X is a mental state

Whether this proposition is true or not will make no difference to the concrete world. Which indicates that this debate is merely conceptual.

Cognitive Qualia

I used to think that debates over concepts didn’t matter. Of course, conceptual clarity is useful because it eases communication and carving up the world neatly makes it easier to handle.

But the debates don’t matter in the sense that you aren’t figuring out anything fundamental about the concrete world. Whether or not there are quarks, whether ants are sentient, or whether egalitarian societies are more productive -- these debates matter. They get at different ways for the world to be in a way that purely conceptual debates do not.

But there’s another way in which these debates matter, something that took me a few years to realize.

I was reminded of this by hearing Eric Weinstein say the following to Josh Wolfe:

The thing that I am talking to now is the projection of you inside of my head. That comes from the stimulation. I mean, I believe that I have eyes, I don't want to get completely Jiggy but just assume that reality is the standard picture of reality. I see you as being across the room for me, but that's not the thing that it's really happening, what’s really happening, if everything I know to be is correct, Is that the thing across the room for me is generated a model in my mind, which is the only thing I've ever interacted with.

This is wrong. Eric spoke to Josh Wolfe, not a model of Josh Wolfe.

But that’s not the main point here, the main idea is that what it’s like to be a direct realist can differ radically from what it’s like to be an indirect realist. In other words, there’s such a thing as cognitive qualia. Qualia refers to the subjective character of mental states. There’s something it’s like to be sad, overjoyed, feel pain, feel pleasure. Likewise, there’s something it’s like to believe that you can see the territory, something else to believe that you’re stuck to seeing the map.

Robin Hanson has called out how beliefs are basically just like clothes. They have a social and functional role:

Functionally, beliefs inform us when we choose our actions, given our preferences. But many of our beliefs are also social, in that others see and react to our beliefs. So beliefs can also allow us to identify with groups, to demonstrate our independence and creativity, and to signal our wealth, profession, and social status.

This picture is insightful, but incomplete. Beliefs have an experiential role as well.