David Deutsch's The Beginning Of Infinity
At first, I was disappointed in this book. I had liked his earlier book The Fabric Of Reality and I had high expectations. The Beginning Of Infinity seemed pedestrian after that - at first.
His main topic, the central intellectual value of good explanations, was interesting in principle, but I'd already got that from his earlier book. He describes good explanations as "hard to vary".
Then he examined themes that I was already familiar with: Evolution as unintelligent design (a la Dennett). Many-worlds. Memetics. Infinity (a la Cantor). It's hard to get excited about stuff I already knew.
Why Are Flowers Beautiful?
Chapter 14 "Why Are Flowers Beautiful?" was the first exciting offering in the book, at least to my eyes. Good art, he says is also hard to vary, just like explanation and design.
He makes his case by talking about flowers. You may think flowers peaceable creatures, but they are the product of a sort of arms race. Flowering plants are symbiotic with pollinating insects, which need to recognize them. But if their flower designs were too easy to imitate, other flowers with poorer nectar would look like them. The insects would sometimes visit the poorer flowers instead, undesirable for both the insects and the proper flowers, benefitting only the free-loading flowers.
So each flower species has an appearance that's hard to imitate. Since no flower has a monopoly on any color or shape, a free-loading flower could easily get the gross appearance right. So flowers have appearances that are "hard to vary". Getting the appearance kind of grossly right won't fool the pollinating insects.patchworkZombie points out that this is unlikely, more likely the sincere flowers try to be memorable while free-loading flowers try to be forgettable
For flowering plants, it's a vital evolutionary design, for us, a pretty sight. This is the nexus Deutsch finds between design and art.
What does he mean, "hard to vary?"
I had to mentally fill in what he means by "hard to vary". By this point in the book I think I basically got what he meant, but he never says what he means by it in so many words. So here's my guess as to what he means by "hard to vary" as it applies to art.
What is it about art that he's saying is hard to vary? You could easily (say) play a wrong note in a Beethoven piano sonata or paint a stupid moustache on the Mona Lisa. That's not hard.
So is he saying it's hard to vary on the receiver's side? That by itself makes no sense. Of course art doesn't vary on the receiver's side, it's the artist who can make it vary, not the audience.
But if I understand rightly, it is nevertheless the audience that delineates what is "hard to vary". We can perceive some sensations and patterns easily, some with difficulty, and some not at all. Far more sophisticated than insects in many ways, but real perceptual powers and perceptual limitations nonetheless.
So an oeuvre is hard to vary if it has cornered a niche in perceptual space from which the easily-made variations produce something not much like the oeuvre. The easy variations give wrong notes and not new tunes, as it were.
It almost seems circular. Varying an oeuvre that's hard to vary produces one that is less hard to vary. That's not a good criterion for "hard to vary".
But it's really about the interaction between ease of variation and subtle perceptual powers. Varying an oeuvre in an easy way, say by changing the pitch of one note, produces something that our subtler perceptual powers see as grossly different, say, by messing up an otherwise good match to an established motif and not leading anywhere.
So if I understand right, he's saying that quality in art is precisely the same thing as being hard to vary in light of the audience's perceptual powers.
This is a good theory
It adds up to the first compelling theory of art that I have seen. It lets subjective perception into the picture, but avoids the post-modern notion that it's all subjective and "ugly is the new pretty". It's properly grounded; the concepts that it's built from are universal, not parochial, and can't be accused of being merely disguised synonyms for beauty. And most importantly, when I hold it in mind while listening to music, it seems to apply reasonably to what I'm hearing.