The one in which the definition of consonante you claim to be universal is.Which book are you referring to? The one in my head?
These answers are intuitive and obviously true.
QED. Intuitive realist, even worse than sicentific realist. You just make things up based on your own perspective. Next thing you're saying the earth is obviously flat because you throw water into a lemon and it falls down, yet if you throw it into a place it stays there. right? That's what you're doing.
It's irrelevant what I define. Definitions are historically constructed, socially mantained and individually experieced. But if you want one of those I can quote a practice where that happens: serialism. Octave is the most dissonant interval there, that's why it is never used and it is avoided [go read Charles wuorinen "simple composition" for instance, for somebody else than me]. If you're in the context of a serial ritual where you're listening to lots of seconds, tritones, sevens, etc... if all of a sudden an octave was played it would completely break the expectations and seen as a "dissonance" and a huge "mistake". Your serialist professor would red mark right there and say something like, make it a seventh instead. or something like that. Context.All you need to do to prove your point is to claim that you define an octave as "dissonant".
You never get it. You keep repeating false claims. It is definable. But you have to define it according to the musical practice you're dealing with, understanding the concepts and behaviours of the people using it. You can't define on a void or becomes meaningless. It is just like saying "A chair is something for you to sit on. This is inuitive and universal". Wrong. It depends on context. If you put it on a museum it can be "art", if you put a pair of trousers and a coat in it is can be "a hanger". If you throw in it a fire to warm you up it can be "wood". Things are defined in context and never in a vacuum. Any chord can be "dissonant" or "consonant" depending on context and who is using it and who is listening to it, where and when. The point of science is to explain WHY and HOW it is being used. Therefore "Chord X" is more consonant than "Chord Y" In context A, because of a,b,c,d.... and is less dissonant in context B because of e,f,g,h... it has a cultural component to it that it can't be ignored.who claims the subject of the argument is undefinable

