Not Jamie and I discussing something, I've no idea who these people are but if they keep talking much longer they're going to get wet feet. Or are they? Perhaps the tide is going out in the picture? I've no idea but I think the purpose of this picture caption is fulfilled and I'll end it here.Given the lack of any decent 'original' content on 
m'blog of late I thought I might post a brief 'discussion' about harmony which occurred on that popular 'social networking' site recently.
The two protagonists are my fine self, and the most distinguished 
Jamie Bullock. I lead off with a 'status update' about material from a string quartet I'm currently writing...
EL ('status update' 17/04/2010): how can two different transpositions of the  same rotational array produce different pitch class sets? I must have  made a mistake. Hopefully the decent bit of music I wrote using one  array is the correct one of the two. Good times.
EL (comment on 'status update' 17/04/2010): Fixed. Got one line wrong when transposing to the second array somehow.  Thought it was odd as the sets were of a different cardinality. Decent  bit of music saved then, all is well with the world (apart from war and  poverty and disease and old age and, stuff).
JB (comment on 'status update' 18/04/2010): Your compositional techniques sound so much like computer programming  (or maths). (Absolutely no implicit criticism intended, BTW). Out of  interest, do you ever keep stuff that works musically, but breaks the  process you are using?
EL (comment on 'status update' 18/04/2010): It is basically maths I suppose. Set theory a bit but it's more like  
combinatorics (from what little I understand of higher mathematics  anyway).
Also geometry plays a role. I plot every set on a clock  face so it's mod 12 arithmetic. Transposition becomes rotation,  inversion becomes reflection etc.
Re keeping stuff that isn't  justified within the system, no. But more specifically I wouldn't find  that material as I don't use my 'ear' for generating material. Only for  auditioning material I make via the 
pre-compositional 
procedures  outlined briefly above.
I have so many ways of generating  material from a basic line or set I have no need to use pitches from  anywhere else, and it sounds better that way to me. I don't trust my  ears any more, I never think 'that would sound better if it were a  semitone or a tritone' or whatever, I just accept the results of the  system and if I don't like it I use different basic material.
It  might sound a bit rigid or dogmatic but if you think about it tonality  is just as 'restrictive'. It's only because it's an ideology that many  don't see it that way, history becomes nature as Foucault might say.
You  wouldn't go from a II-V- progression to a dense chromatic cluster for  instance, you'd use tertiary harmony and would consider the root  progression. If you list the 'rules' of tonality there is nothing  'natural' or 'free' about it.
The same process applies, one  auditions the available material (an output from the system) and one  chooses the 'best' stuff.
Same could also be said for our western  tuning system. It's sort of amusing that we have a sort of romantic  noble savage popular music culture that suggests one can 'invent' or  'create' new music 'freely' by 'ear' as a product of 'inspiration'  without any 'training', when in fact the harmonic system employed is just  as rigid and limited as any other and the only reason the untrained can  write songs/music easily is because of the hard work of many theorists  and musicians over hundreds of years.
Oh, the irony.
(this discussion continues in the comments section, feel free to join in).
Tinyurl for this post: http://tinyurl.com/y66un4p