It's becoming more and more clear to me that the concept of a person as an entity which is always the agent of personal activity is rationally incompatible with naturalism for personal identity reasons. If naturalism is true, multiple instantiation considerations are just about undeniable, and so computers can be persons. But there really is no way of maintaining a viable concept of persons as well defined entities once we consider the vast array of manipulation that can happen with computing machines. Consider an intelligent system built up as a decentralized swarm of flying, mutually communicating simpler devices exhibiting rational agency collectively but not individually. The idea that there is an entity, a person, under such circumstances is implausible. Think of a community consisting of a number of such swarms which routinely exchange components. Sometimes two swarms fly through each other, and out come two swarms with the member devices being different, and sometimes out comes one bigger swarm. Is there going to be a fact of the matter as to identity conditions?
If I'm right, and if materialism is right, then "personhood happens", but there being a special kind of entity, a person, there where personhood is happening is not going to be a necessary condition for "personhood to happen". I think this conclusion is absurd (for one, it would mean that such a swarm would be wrong if the thought occurred: "I think, therefore I am"), and so materialism is false.
But suppose we don't think the conclusion absurd. Would it make sense to say that there is such a thing as a person in our own case? Or should we still then say that "personhood happens"? I suspect the latter, unless we just identify the "person" with the animal in whom personhood happens. But the latter isn't going to be that plausible, I think, once we realize that one and the same animal brain could in principle, by parallel processing, support more than one stream of rational agency.
If all this is right--and there are a lot of promissory notes here--then if materialism is true, there are no persons, and hence I do not exist.