[xgk]

   And course the reply:

I found Aphex Twin's reply disappointing.

Like a petulant child he essentially negated Stockhausen's points, without engaging with them. It seems to me that Stockhausen was trying to be helpful -- after all he had been a music teacher for nearly 1/2 century with academic offspring like Kraftwerk and Can. Aphex Twin seemingly was unable/unwilling to see that there are other approaches to music than the orthodoxy of 1990s dance music. Aphex Twin's main musical criterion seems to be dancablility:

    you can't dance to. Do you 
    reckon he can dance? You could 
    dance to   Song of the Youth, but 
    it hasn't got a groove in it, 
   there's no bassline."

I would argue to the contrary: dance music -- whatever its merits for dancing -- cannot be interesting as art music. Why? Because dancing, specially dancing well, is itself demanding: most brain capacity is used for moving the body along to the music in the right way, and that capacity is missing for listening to and analysind the fine points of the music.

   Reich, Glass et al. might disagree.

Of course the art music tradition of American mimimalism that you refer to, does change tempi and changing rhythms quite a great deal. It does so in novel ways that had not been explored in previous classical traditions. That's the main novelty that American mimimalism gave to the world.

   Periodicity is what ...

I agree with that, and add that modern pop-music errs on the side of too much periodicity, which renders it uninteresting as art-music, but useful as aural background and for dancing.

[specialist]

What is art?

IMHO:

Dance(able) music, like all music/noise, is about altered states of awareness.

There's sometimes something wonderful about reggae, house music, chanting, work songs that can change your frame of mind.

But then again all music (genres) do that for me.

[pmoriarty]

What would be much more interesting is if instead of bickering, Stockhausen and Aphex Twin collaborated to create a new work together, like Beethoven and Goethe might have. What a wasted opportunity.