Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: You don't know how bad most things are nor precisely how they're bad., published by Solenoid Entity on August 4, 2024 on LessWrong.

TL;DR: Your discernment in a subject often improves as you dedicate time and attention to that subject. The space of possible subjects is huge, so on average your discernment is terrible, relative to what it could be. This is a serious problem if you create a machine that does everyone's job for them.

See also: Reality has a surprising amount of detail. (You lack awareness of how bad your staircase is and precisely how your staircase is bad.) You don't know what you don't know. You forget your own blind spots, shortly after you notice them.

An afternoon with a piano tuner

I recently played in an orchestra, as a violinist accompanying a piano soloist who was playing a concerto. My 'stand partner' (the person I was sitting next to) has a day job as a piano tuner.

I loved the rehearsal, and heard nothing at all wrong with the piano, but immediately afterwards, the conductor and piano soloist hurried over to the piano tuner and asked if he could tune the piano in the hours before the concert that evening. Annoyed at the presumptuous request, he quoted them his exorbitant Sunday rate, which they hastily agreed to pay.

I just stood there, confused.

(I'm really good at noticing when things are out of tune. Rather than beat my chest about it, I'll just hope you'll take my word for it that my pitch discrimination skills are definitely not the issue here. The point is, as developed as my skills are, there is a whole other level of discernment you can develop if you're a career piano soloist or 80-year-old conductor.)

I asked to sit with my new friend the piano tuner while he worked, to satisfy my curiosity. I expected to sit quietly, but to my surprise he seemed to want to show off to me, and talked me through what the problem was and how to fix it.

For the unfamiliar, most keys on the piano cause a hammer to strike three strings at once, all tuned to the same pitch. This provides a richer, louder sound. In a badly out-of-tune piano, pressing a single key will result in three very different pitches. In an in-tune piano, it just sounds like a single sound. Piano notes can be out of tune with each other, but they can also be out of tune with themselves.

Additionally, in order to solve 'God's prank on musicians' (where He cruelly rigged the structure of reality such that (32)n2m for any integers n, m but IT'S SO CLOSE CMON MAN ) some intervals must be tuned very slightly sharp on the piano, so that after 11 stacked 'equal-tempered' 5ths, each of them 1/50th of a semitone sharp, we arrive back at a perfect octave multiple of the original frequency.

I knew all this, but the keys really did sound in tune with themselves and with each other! It sounded really nicely in tune! (For a piano).

"Hear how it rolls over?"

The piano tuner raised an eyebrow and said "listen again" and pressed a single key, his other hand miming a soaring bird.

"Hear how it rolls over?"

He was right. Just at the beginning of the note, there was a slight 'flange' sound which quickly disappeared as the note was held. It wasn't really audible repeated 'beating' - the pitches were too close for that. It was the beginning of one very long slow beat, most obvious when the higher frequency overtones were at their greatest amplitudes, i.e. during the attack of the note.

So the piano's notes were in tune with each other, kinda, on average, and the notes were mostly in tune with themselves, but some had tiny deviations leading to the piano having a poor sound.

"Are any of these notes brighter than others?"

That wasn't all. He played a scale and said "how do the notes sound?" I had no idea. Like a normal, in-tune piano?

"Do you hear how this one is brighter?"

"Not really, honestly..."

He pul...