This reminds me of high school debate class, haha. I always wished we had a debate club. Of course, there's little point to this if you're not arguing the opposite of what you believe, so it's lucky that I'm responding when I am, since I personally believe people should be allowed to choose when to end their life in at least some cases.
The distinction in law comes from the fact that people in persistent vegetative states often (as in, most of the time) never come out of them. Pain, however, is a much more vague concept. It's subjective and often subsides with time, in some cases altogether. Our ideal system always prioritizes long-term health over short-term and the big thing is that we don't want to end someone's life if they still might be able to enjoy their life further down the line. People who will likely never wake up again are likewise highly unlikely to ever have the chance to regret having their life ended, so it's a lot less difficult of a decision.
The ethical dilemma is that in many of these cases, their situation may only be temporary for whatever reason. Perhaps their condition may improve, either due to medicine or possibly some other reason. Often times, patients in severe pain aren't considering their long-term prospects, they're too caught up in their current suffering. But that suffering is often temporary. Is it ethically tolerable to comply with someone's wishes to end their own life if their ability to make decisions itself is compromised and they have a decent shot at improvement?
In many cases, this is true. But this isn't universally true. In other instances, these new treatments do come out during their life and can sometimes lead to vast improvements in condition.
Either way, terminal patients are not the only sort in question.
To distinguish my position with yours, I agree with conclusion you have provided, that some people should be able to choose whether to end their lives provided a particular protocol to assess pain, risk, psychology, among other factors as to the patients quality years of life left (if any). However, there is no underlying principle or logic used to support the argument (it is because it is). Since, risk, pain, and prognosis, some criteria that are alluded to in your argument, are never tied to an underlying premise which then allows us to conclude, logically, that risk, pain, and prognosis should even allow for a patient to have agency in their medical care.
Further, you assert that in an ideal healthcare system, it should ALWAYS favor long-term health rather than short term health? If cumulatively applied, then the patient with a less than favorable, by still decent chance of survival could very well then be required to supply their organs to the lives of other patients that have a better prognosis (in terms of length of quality years of life) with an organ transplant than the donor. If it is true that long term health must be considered over short term health, than the donor must then give up that organ to another person with a greater quality year of life potential. Further, medical insurance should provide a greater investment in younger population than in the elderly population with this principle.
There are negative consequences to this principle in that it will have negative social and political implications. Negative implications, I define as those that stir volatility. Volatility arises when individuals are forced to do something against their will that causes them or their relatives harm. However, when the patient with a higher prognosis wait for a donor, their is a lesser chance that the patient and relatives will be volatile as there is a lesser degree of entitlement to the organ donation. That is, people are more volatile when something is taken away than they are when they don't receive a benefit they are not guaranteed. The theory of loss aversion.
Further, you make the point that the patient for the sake of his own choice (implying an inherent entitlement) should be allowed to make medical decisions, however, it is not grounded in any sort of underlying principle aside from the spurious point that long-term should always be considered over short-term health decisions. What else grounds the reason as to why someone is entitled choice and agency of their life?
I would make the case that choice of life should be granted to the patient, if medically competent, and assuming the patient has a poor prognosis and suffering pain, and the reason why is to establish agency of citizens to both deciding to live and deciding to die is based on the principle of political volatility. That is, if elderly patients are not allowed choice in the matter of choosing to live, as a young adult, they will feel less invested in their health and outlook on life presuming there is no choice to be allowed to live with certain life conditions. Further, if anyone is forced to live, the person is paying to suffer in medical costs, which may imbue them and their families a sense of volatility. And, political volatility, and forced obligation over something in which has negative impacts on their lives and others, reduces the percentage of satisfied citizens, and increases radical behavior and instigates political dissent.
Political volatility is negative to the state and the citizens that live in it. Political instability, time, and resources are exhausted on court cases, legal proceedings, legislative deliberation, among other things on an issue in which political volatility can be better avoided. Though the counter to my point is that allowing euthanasia by choice will cause political unrest of the dissenting group, against such a legal measure. And, any wasted investment in long-term controversy and disgruntled citizens and groups lends itself to harm on society, as the wasted resources listed above could bolster quality of life (happiness) in some other form or fashion.
That is why I will form of synthesis of your principle and my own. The reason why patients should be able to choose their own death is to procure long-term political stability, rather than short term forecasts of political volatility (for instance the race riots of the 60's were politically volatile in short-run, but reduced volatility in the long run.) Further, in establishing long-term reduced volatility, citizens are more satisfied, less divided, and therefore more happy. And happiness is the ultimate goal of collective society. There is no decision or rationale that can be made without accounting for this principle of collective happiness or "the good".
