Wow.
He said that the voices in your head have been yours all along. Just like you said. Just like everybody else.
That has been well established. No argument there. I only wanted to know how Walt knew what was in my head. He already answered it honestly when he said "I don't know". And he's right, he doesn't know. And you don't either. You have zero proof of voices or lack thereof. You only know what I've said today which is "I've not had voices in my head except for my own".
Now, based on what I've told you, you know I don't have voices in my head. But, you still don't know if everybody else does or not, unless they also tell you. See how that works? Wow