"Conversation Galante"?

Ineffable Moon

Aris Messinis/Agence France-Presse - Getty Images

(Image from New York Times)

Back in the early 1980s, when I was safely ensconced in history of science at UC Berkeley, I recall a conversation with Bruce Wheaton -- one of the instructors who worked with John Heilbron at the Office for the History of Science and Technology -- about why the moon looks larger on the horizon than at its zenith.

Now, Bruce was a smart guy, and he knew more about the history of technology than just about anyone I knew -- if, by "history of technology," one means an internalist history of the subject. In fact, I sat through his lectures on technology when I worked as one of his teaching assistants and learned a great deal about machines. He was quite gifted at making the technical details clear and excellent in demonstrating how one technical device led to another through improvement of some mechanical aspect or other, or through combining devices to form a new, more complex device -- almost as if the machines were evolving through alternately continuous and punctuated styles of evolution. I found myself unexpectedly fascinated, and I half-expected to finish the semester capable of building my own car!

But Bruce could at times be hermeneutically inaccessible.

To my question concerning why the moon looked larger at the horizon, he replied, "It doesn't. If you measure its diameter, you'll find that it's the same."

"I understand that," I assured him. "What I want to know is why the moon looks larger."

"It isn't larger," he countered.

"I know," I said, perhaps a bit more curt than necessary, "but why does it look larger?"

"It doesn't," he insisted.

After a couple more whirls on hermeneutic circles of this sort, I was ready to get off that conversational roller coaster. Bruce could keep his mathematically invariable moon, but I'd stick to my qualia-ridden impression and hope for an answer to my query someday.

The late 1960s band Creedence Clearwater Revival claimed that "Someday Never Comes", but someday came yesterday when I read Alison Gopnik's article "Consciousness: The Great Illusion?" (May 20, 2011), a New York Times review of a recent book by Nicholas Humphrey, Soul Dust: The Magic of Consciousness. In her review, Ms. Gopnik speaks of consciousness and notes that some aspects of consciousness can be explained:

For example, why does the moon look so much larger when it's at the horizon than when it's overhead, at the zenith? This is a question about conscious experience -- about how the world looks to us -- not about behavior and brains. And there is a clear and convincing evolutionary explanation.

The visual system wasn't designed to deal with objects that are thousands of miles away. It was designed to accurately judge the size of close, evolutionarily relevant objects like apples. As an apple moves closer or farther away, it will project a larger or smaller image on my retina. But I don't see the apple expand and contract. I see an apple with a concrete, stable size. This is because my brain evolved to combine information about the size of the retinal image with information about distance to create a single, constant visual experience.

The retinal image of the moon is always about the same size. But the horizon looks farther away than the zenith, perhaps because we see that other objects are in front of the horizon while the zenith is unoccluded. The brain determines that the horizon moon must therefore actually be larger than the zenith moon. And, voilà, the rising moon looks much bigger.

Drawing upon Humphrey's ideas, Gopnik adds:

So we actually have a good and interesting naturalistic explanation for this particular feature of our conscious experience and many others like it. But it seems that we can't explain the most important thing: Why does the moon look like anything at all? What explains that ineffable je ne sais quoi, that irreducible magic of experience? That big, beautiful moon doesn't just feel like the outcome of a cool calculation. And it isn't looming up at just anyone, but at me, the equally ineffable and irreducible self.

That's more qualia, the utterly ineffable kind. I can just about almost nearly grasp what she's referring to, though not effing quite . . . so as for this nearly effable moon, "It may [as well] be Prester John’s balloon," after all, if anything specifically particular at all.

Now, why is that, Bruce? And where is your own ineffable self these days?