Yeah I mean I can understand that logic, but to me this is a deeply unusual edge case where applying the top down moral principle of "it's bad to kill someone who doesn't want to die" seems like it produces the wrong results.
I do believe that Me with Alzheimer's isn't really Me anymore in a meaningful sense, but at the same time we have a lot in common - more in common than any person could have in common with a stranger, or friend, or family member etc etc.
In this scenario, there's a loss of mental continuity and memories, BUT we would still have in common:
- essentially the same body
- likely similar mannerisms
- similar or the same voice
The way I conceptualise this is a little similar to the Yeerk mind control scenario in Animorphs - there's essentially an "imposter" in my head controlling my body. Because Me with Alzheimer's looks like me, talks like me, walks like me, but isn't quite me!
And that has important implications for me in terms of how I pass away. I don't want people to remember me as someone else, who I have no control over and will never meet. And, more importantly, I don't want someone who shares my name and body to hurt the people I care about. To me, that gives me a moral "stake" in this person's existence (or lack of). I'm directly impacted by this person's future existence and actions in a way that's different from an ordinary relationship between persons. If I think there's a good chance a hostile agent may have semi to full control over my body/actions, I will arrange my life differently to minimise the damage they can do. But I'd prefer they just don't exist at all!
Plus, even though I do think Me with Alzheimer's is a distinct person from Current Me, Me with Alzheimer's is still composed of me to some extent. Elements of me would still persist (to declining degrees as the disease worsens) in Me with Alzheimer's. It's like when you're talking to someone with dementia or schizophrenia or another illness where the person has a tenuous grasp of reality. From time to time, a coherent self emerges and you can have a meaningful conversation with "their old self" for a short while. They remember who you are, can answer questions in a sensical way etc. Again, I think this gives Current Me some "stake" in whether Future Impaired Me should exist or not.
But I'd also argue when someone is sufficiently detached from reality like that, they can't meaningfully consent anymore to pretty much anything. They are so unstable as a person that them saying "yes" or "no" at a point in time doesn't really mean all that much. It's a bit like how we don't view young children or drunk people as capable of giving consent in a meaningful way. Trying to squeeze "consent" out of someone in that impaired state is unreliable at best. That's generally why we establish an advocate/guardian/representative for these people - someone who can (hopefully) be trusted to look out for their best interests.
In the case of euthanasia, I'd argue the logical person to act as advocate/guardian/representative to my mind is the person prior to cognitive decline. As stated above, they have the most in common. But, failing that, a nominated representative is better than the alternative - a random crapshoot where someone's answer to "do you want to die" could varies on a day to day, hour by hour basis.
If it helps, I'm thinking here about my experiences with my grandfather who passed away from dementia in 2019. It's hard, now, to remember who he was before he started declining. He became someone entirely different. For nearly all of his life he was a compassionate, gentle man who was incredibly generous with his time. With dementia, he turned into a confused, emotionally volatile, and sometimes physically dangerous man who had to be managed like a child or a pet.
My grandma and my family spent many hours caring for this man and trying to ease him through his decline. We then spent thousands of dollars to put him in aged care once he was too hard to manage for my grandma at home, and thousands of hours visiting him.
I don't resent the time and effort spent on caring for him, or feel like the money spent on aged care was a waste. He was Catholic and it's unlikely he would have wanted anything different. People should be able to die like that if they want to. But it's clear to me that something was lost in that experience. When I think of him, I think of the aged care facility. I think of how he didn't know who I was. I think of his confused mutterings and ramblings, of how he would get upset and make this pitiful whining noise, and how thin and skull-like his face looked when he passed away. I think about how my grandma became much happier after he finally died. She would never say it but it was clear his death was a relief and a burden taken from her.
I don't think about the many happy times we had together when I was growing up. It's difficult now to remember. I know they happened, intellectually, but I can't feel and recall these memories in the way I can recall the memories above. He was a constant presence around the house but I can barely remember anything about him. I know he loved gardening and would regularly come over to our place to weed and trim trees and bushes, but do I remember this or is that just a fact I know about him? I'm not entirely sure.
In contrast, I saw much less of my grandpa's brother (my great-uncle) growing up, but in many ways I have a much clearer recollection of him. He passed away much more suddenly six months after my grandpa in 2020. I can remember his voice and personality, his cackle of a laugh, and how thin, tall, and wiry he was. I remember him as him, more or less.
I'd like to be remembered as me, more or less, too.
