John Keats's Lamia (1819) surely deserves some kind of award for Most Famously Annoying Poetry:

...Do not all charms fly

At the mere touch of cold philosophy?

There was an awful rainbow once in heaven:

We know her woof, her texture; she is given

In the dull catalogue of common things.

Philosophy will clip an Angel's wings,

Conquer all mysteries by rule and line,

Empty the haunted air, and gnomed mine—

Unweave a rainbow...

My usual reply ends with the phrase: "If we cannot learn to take joy in the merely real, our lives will be empty indeed." I shall expand on that tomorrow.

Today I have a different point in mind. Let's just take the lines:

Empty the haunted air, and gnomed mine—

Unweave a rainbow...

Apparently "the mere touch of cold philosophy", i.e., the truth, has destroyed:

Haunts in the air

Gnomes in the mine

Rainbows

Which calls to mind a rather different bit of verse:

One of these things

Is not like the others

One of these things

Doesn't belong

The air has been emptied of its haunts, and the mine de-gnomed—but the rainbow is still there!

In "Righting a Wrong Question", I wrote:

Tracing back the chain of causality, step by step, I discover that my belief that I'm wearing socks is fully explained by the fact that I'm wearing socks... On the other hand, if I see a mirage of a lake in the desert, the correct causal explanation of my vision does not involve the fact of any actual lake in the desert. In this case, my belief in the lake is not just explained, but explained away.

The rainbow was explained. The haunts in the air, and gnomes in the mine, were explained away.

I think this is the key distinction that anti-reductionists don't get about reductionism.

You can see this failure to get the distinction in the classic objection to reductionism:

If reductionism is correct, then even your belief in reductionism is just the mere result of the motion of molecules—why should I listen to anything you say?

The key word, in the above, is mere; a word which implies that accepting reductionism would explain away all the reasoning processes leading up to my acceptance of reductionism, the way that an optical illusion is explained away.

But you can explain how a cognitive process works without it being "mere"! My belief that I'm wearing socks is a mere result of my visual cortex reconstructing nerve impulses sent from my retina which received photons reflected off my socks... which is to say, according to scientific reductionism, my belief that I'm wearing socks is a mere result of the fact that I'm wearing socks.

What could be going on in the anti-reductionists' minds, such that they would put rainbows and belief-in-reductionism, in the same category as haunts and gnomes?

Several things are going on simultaneously. But for now let's focus on the basic idea introduced yesterday: The Mind Projection Fallacy between a multi-level map and a mono-level territory.

(I.e: There's no way you can model a 747 quark-by-quark, so you've got to use a multi-level map with explicit cognitive representations of wings, airflow, and so on. This doesn't mean there's a multi-level territory. The true laws of physics, to the best of our knowledge, are only over elementary particle fields.)

I think that when physicists say "There are no fundamental rainbows," the anti-reductionists hear, "There are no rainbows."

If you don't distinguish between the multi-level map and the mono-level territory, then when someone tries to explain to you that the rainbow is not a fundamental thing in physics, acceptance of this will feel like erasing rainbows from your multi-level map, which feels like erasing rainbows from the world.

When Science says "tigers are not elementary particles, they are made of quarks" the anti-reductionist hears this as the same sort of dismissal as "we looked in your garage for a dragon, but there was just empty air".

What scientists did to rainbows, and what scientists did to gnomes, seemingly felt the same to Keats...

In support of this sub-thesis, I deliberately used several phrasings, in my discussion of Keats's poem, that were Mind Projection Fallacious. If you didn't notice, this would seem to argue that such fallacies are customary enough to pass unremarked.

For example:

"The air has been emptied of its haunts, and the mine de-gnomed—but the rainbow is still there!"

Actually, Science emptied the model of air of belief in haunts, and emptied the map of the mine of representations of gnomes. Science did not actually—as Keats's poem itself would have it—take real Angel's wings, and destroy them with a cold touch of truth. In reality there never were any haunts in the air, or gnomes in the mine.

Another example:

"What scientists did to rainbows, and what scientists did to gnomes, seemingly felt the same to Keats."

Scientists didn't do anything to gnomes, only to "gnomes". The quotation is not the referent.

But if you commit the Mind Projection Fallacy—and by default, our beliefs just feel like the way the world is—then at time T=0, the mines (apparently) contain gnomes; at time T=1 a scientist dances across the scene, and at time T=2 the mines (apparently) are empty. Clearly, there used to be gnomes there, but the scientist killed them.

Bad scientist! No poems for you, gnomekiller!

Well, that's how it feels, if you get emotionally attached to the gnomes, and then a scientist says there aren't any gnomes. It takes a strong mind, a deep honesty, and a deliberate effort to say, at this point, "That which can be destroyed by the truth should be," and "The scientist hasn't taken the gnomes away, only taken my delusion away," and "I never held just title to my belief in gnomes in the first place; I have not been deprived of anything I rightfully owned," and "If there are gnomes, I desire to believe there are gnomes; if there are no gnomes, I desire to believe there are no gnomes; let me not become attached to beliefs I may not want," and all the other things that rationalists are supposed to say on such occasions.

But with the rainbow it is not even necessary to go that far. The rainbow is still there!