> The question is whether we have justification to believe that it actually exists

I understood this to mean that you were doubting whether subjective experience actually exists, and I responded by arguing that it is not possible to doubt that your own subjective experience exists since you (I, at least) experience it directly, which is different than the class of now-refuted inferences that you were comparing it to in. I was not making any argument about where it comes from or what causes it.