Yes, I'd be happy to address this.
It's about autonomy. It's about how we project our autonomy. Really, what advance requests do is project our autonomy into the future, into the person that we will become. We know that we change all the time, from day to day. You are changed by my words in some way at this moment. It's not that we are fixed people at any time in our lives. It's really a matter of this question: If somebody is to decide for me when I am in this debilitated condition at some unknown time in the future, who best is in a position to make that decision?
I think that as a scholar of the neurobiology of autonomy—because I've published on it extensively—I would say that clearly it is me, but there is also a penumbra of autonomy that exists in the reality where we're not quite as atomized individuals as we think. That's where the family and friends and other people come in, and including them in that discussion is very important. However, the decision should properly rest with me.