TC, I just read your blog regarding metal and racism and I just want to say that it was a good read, with several solid retorts to the idea that racism and bigotry is somehow intrinsic to metal culture.
In terms of ontologically attempting to define the essence of metal, I think that question will lead, ultimately, nowhere. For instance--and this is somewhat irrelevant in terms of content, but the basic idea is the same--I am a Film Studies student and have examined some of the early theorists in the field such as Munsterberg, Arnheim, Bazin, and Eisenstein, who have all tried to answer the ontological question of "What is cinema?". Unfortunately, however, all have failed to find it, outside of prescribing their own personal preferences for the art of cinema (art is, for them, synonymous with the essence of the medium). The same thing applies to your line of questioning here, I think, but is even more tenuous, IMO. This is because Film is an entire medium, not just simply a genre; metal is only a small, relatively esoteric genre of pop music. And if theorists have tried and failed to define the essential means of an entire medium, I think attempting to do something similar but with regard only to a specific genre is even more misguided and will yield only unsatisfactory results (such as the circular logic of "To like metal, is to be metal" ad infinitum).
Thus, in this age of cultural fragmentation, attempting to find the underlying or guiding principle of a specific genre of music will only result in over-generalizations and construed archetypes/misnomers about the culture surrounding it.
That being said, good luck anyways
.