Following the success of the first installment (thanks for all the succulent comments!), here is another tough thinking question for you. Before that, a couple of updates.

Last week I had a lot of fun being interviewed by Jay Springett of Experience.Computer. Jay runs a truly unique podcast, focused specifically on an activity that I feel people should do and share more: "curious introspection", or the careful examination of what your consciousness and perception are like and feel like from the inside. I care about it so much that I maintain a living list of my and others' introspective descriptions.

The moment you start reading/listening to this kind of mental spelunking you realize how deep, varied, and mysterious it all is. We (including our scientists) have only scratched the surface in our understanding of these matters.

Experience.Computer is specifically about what it's like to imagine things—images, motions, places, sensations. Jay has aphantasia like me, and SDAM like me, so his podcast starts with a long and intriguing series of questions to his guests about what really happens in their mind when they imagine concrete things like balls rolling on tables, or remember events from the past. The kind of questions that people would never think or bother to ask—until they realize that everyone has a different answer!

Apparently I was the first aphantasic to join the show as a guest, so Jay and I had fun comparing our experiences. It turns out that even between aphantasics the way the mental world is experienced can vary a lot. "A lack of imagery" is too reductive a term for this strange trait.

If this kind of exploration intrigues you, you can listen to the podcast here or on the major podcast platforms.

Jay was extremely kind and curious throughout, and he knows how to nudge you to dig deeper and find words to express the inexpressible. His other podcast episodes and blogs are well worth checking out, too.

As I mentioned last time, I'm working on creating a buffer of blog posts to free myself from the curse of the weekly deadline, and that's why you're seeing fewer posts from me. I'm working on some very exciting projects that I can't wait to share with you here—the temptation is to publish them as soon as they're finished, but I will resist. I. Will. Resist.

Now for the open question to the community: share your thoughts in the comments below, and don't hesitate to respond to other people's ideas. Who knows what new thinking tools will come out of the mix?

Q: What Is Left?

My question is about this famous quote from Philip K. Dick:

Reality is that which, when you stop believing in it, doesn't go away.

— Philip K. Dick, I Hope I Shall Arrive Soon

This is very compelling. The first time I read this sentence I thought it was very clever. If you stop believing in a tree standing right in your path and walk on, you'll get a bruise on your forehead. Using that as proof that the tree is real sounds reasonable and pragmatic.

But (to no surprise for long-time Aether Mug readers), things aren't that straightforward when you look at them from a different angle framing.

I realized that it is not only the physical world that differs from the particular way we see it; that all reality is perhaps equally dissimilar from what we believe ourselves to be directly perceiving, which we compose with the help of ideas that do not reveal themselves but are functioning all the same, just as trees, the sun, and the sky would not be the way we see them if they were perceived by creatures with eyes differently constituted from our own, or with organs other than eyes, which fulfilled the same purpose and conveyed equivalents of trees and sky and sun, but not visual ones.

— Marcel Proust, In Search of Lost Time - The Guermantes Way

So reality is there, but it's different depending on all the details of how you look at it? That sounds problematic.

Philosophers have thought about what parts of reality are "really real" vs those that are "kinda real". One way to draw this boundary is explained concisely by philosopher Bas C. van Fraassen:

Wilfrid Sellars presented us with a clear dichotomy: the world as described by science, which he called the Scientific Image, and the world as it appears to us, the Manifest Image. Not that the dichotomy was so novel: Sir Arthur Eddington's famous example of the two tables is an obvious precedent. The table we see is solid, it is mostly material even if there are some small pores and little gaps in the wood. The table science describes, however, is mostly empty space, filled with small electrically charged particles frantically whirling around in the void. So the Scientific Image is astonishingly different from how things appear to us. Yet science is meant to represent the very same world in which we live—and there is the rub. ...

Wilfrid Sellars argued that the two world pictures are in irreconcilable conflict, and that the infinitely superior Scientific Image must eventually displace the Manifest Image altogether.

— van Fraassen, The Manifest Image and the Scientific Image

But Daniel Dennett had a different take on the difference between the scientific image and the manifest image.

Sometimes the sweeping negative claims encompass all of the manifest image: the items in the official ontology of the scientific image really exist, but solid objects, colors, sunsets, rainbows, love, hate, dollars, home runs, lawyers, songs, words, and so on, don’t really exist. They are useful illusions, perhaps, like the user-illusion of the desktop icons. The patterns of colored pixels on the computer screen are real, but they portray entities that are as fictional as Bugs Bunny and Mickey Mouse. Similarly, some would say, the manifest image has some reality as a collection of images—the movie we live in, perhaps—but it is a mistake to think of the “things” we interact with and manipulate, and fall in love with, as reality.

That’s a defensible position, I suppose. In fact, it’s a version of what I have said about the manifest image of each species: a user-illusion brilliantly designed by evolution to fit the needs of its users. My version differs only in being willing and eager to endorse these ontologies as ways of carving up reality, not mere fictions but different versions of what actually exists: real patterns. The more shocking way of saying it—“we live in a fictional world, in a dream world, in unreality”—tends to cause confusion because it suggests we are somehow victims, duped by some evil force.

— Daniel Dennett, From Bacteria to Bach and Back

Come to think of it, the scientific image seems a bit suspicious, too. Take the scientific concept of "force", introduced by Newton as a fundamental mechanism in the laws of nature. To this day, every schoolchild studies Newton's Three Laws about how physical objects must behave in the presence or absence of forces. Nothing is more worthy of being enshrined in Sellars' scientific image than force, right?

But the idea of force as a fundamental "thing" was rendered obsolete in the 19th century when Faraday and Maxwell introduced the much more powerful concept of "field". Now things actually move not because of forces—invisible arrows driving their acceleration—but because they react to the presence of invisible fields that pervade all space. That's the scientific image!

Then general relativity and quantum field theory arrived, and we reframed the reason things move yet again: gravity is actually spacetime curvature and the other three fundamental forces are actually exchanges of virtual gauge bosons. Both forces and fields are still taught in school and used regularly by physicists, but they're now understood to be "just" simplified models of those more sophisticated real scientific image concepts.

Is this the end of the process? Will we ever have to stop believing even in spacetime and bosons?

That was a rhetorical question. My question for you is about Philip K. Dick's initial quote:

When you stop believing, what is left of reality? What doesn't go away?