By that sense, if qualia have no discernible impact on any part of the system, in what sense do they exist? One can take this thought further. Red vs green lig

By that sense, if qualia have no discernible impact on any part of the system, in what sense do they exist? One can take this thought further. Red vs green light have real physical properties that affect one's subjective experience of them. For example different colors' physical properties change the way that they are perceived in low light conditions, the way they are perceived when placed next to other colors, etc. So at the end of the day even if hypothetically one person's qualia for red is swapped for green, you end up with a green that acts an awful lot like a red for all intents and purposes in the brain. Edit: So my personal hunch is that qualia can't be meaningfully said to exist.