[doph]

I found Chiang's argument a little incoherent, but I think he _is_ essentially saying this. "Knobs and dials" are the opportunity to make all the little decisions that Chiang's definition of art requires. He says explicitly that someone who has developed "hacks" for an image generator has engaged in the artistic process. I think he uses the term "hacks" to mean that the artist found additional, unexposed controls (aka knobs and dials) over the model.