this gets highly philosophical and I am not so sure there could ever be an answer. I used to care for highly disabled teens (wheelchair bound unable to talk or do anything for themselves - needed to be fed, bathed, wore diapers etc.). Some of them looked like they were enjoying themselves, but others looked like they were in constant pain. Some were permanently disfigured into uncomfortable positions and I would hear them practically whimpering the whole day. They would never be able to communicate with us that they were unhappy existing so how are we to know? What we define as quality is based upon our own experiences, if we imagine what it's like to lose the things we are so used to everyday (summed up primarily to freedom I suppose). But it could very well be different for those who have never experienced those things to begin with. I do not think anyone else has the right to decide for anyone else whether their existence is quality. Though I understand it gets tricky when someone else needs to provide any and all care for said individual. Responsibility falls upon someone