Your heuristic is only useful if it’s actually true that being self-sustaining is strongly correlated with being a person. If this is not true, then you are excluding things that are actually people based on a bad heuristic. I think it’s very important to get the right heuristics: I’ve been wrong about what qualified as a person before, and I have blood on my hands because of it.
I don’t think it’s true that being self-sustaining is strongly correlated with being a person, because being self-sustaining has nothing to do with personhood, and because in my own experience I’ve been able to create mental constructs which I believe were people and which I was able to start and stop at will.
Edit: You provided evidence that being self-sustaining implies personhood with high probability, and I agree with that. However, you did not provide evidence of the converse, nor for your assertion that it’s not possible to “insert breakpoints” in human plurality. This second part is what I disagree with.
I think there are some forms of plurality where it’s not possible to insert breakpoints, such as your alters, and some forms where it is possible, such as mine, and I think the latter is not too uncommon, because I did it unknowingly in the past.
Your heuristic is only useful if it’s actually true that being self-sustaining is strongly correlated with being a person. If this is not true, then you are excluding things that are actually people based on a bad heuristic. I think it’s very important to get the right heuristics: I’ve been wrong about what qualified as a person before, and I have blood on my hands because of it.
I don’t think it’s true that being self-sustaining is strongly correlated with being a person, because being self-sustaining has nothing to do with personhood, and because in my own experience I’ve been able to create mental constructs which I believe were people and which I was able to start and stop at will.
Edit: You provided evidence that being self-sustaining implies personhood with high probability, and I agree with that. However, you did not provide evidence of the converse, nor for your assertion that it’s not possible to “insert breakpoints” in human plurality. This second part is what I disagree with.
I think there are some forms of plurality where it’s not possible to insert breakpoints, such as your alters, and some forms where it is possible, such as mine, and I think the latter is not too uncommon, because I did it unknowingly in the past.