One note about terminology: there is no such thing as a third-person perspective. The central case of a perspective is a point or timeline in spacetime that things can be viewed from (see: perspective drawing). A more general notion of perspective is that of a set of nodes in a causal graph from which indexical references to other graph nodes can be defined. But in any case these perspectives are necessarily first-person, since they are from somewhere.
You could try to use the ontology of physics to define hypothetical perspectives on our universe that are outside of our universe, but once precisely defined, these would also be first-person, and defining these perspectives would be complicated by issues like defining objects and interpretations of quantum mechanics.
In the sleeping beauty problem, it is sensible to talk about the experimenter’s perspective, but not to talk about a non-specific third-person perspective.
(as one case of this: you talk of using names to address individuals from a third-person perspective. But, unless your names are really really long, this doesn’t work in a big universe if the third-person perspective is taken to be some perspective definable from physics, since there are more individuals than short names in a big universe. It does work if by “third-person perspective” you mean some first-person perspective, e.g. that of a member of a group or some intersubjective perspective formed from those of the group members, that needs to uniquely refer to each of some not-extremely-large number of individuals who are spaciotemporally close)
EDIT: just realized that “first-person” has the implication that the perspective is from some person, i.e. a kind of mind. But not all perspectives are from a mind (e.g. camera perspectives). They are still located in a particular place in a causal graph (such as spacetime), though.
I think you are correct that all perspectives are ultimately first-person. That’s why I had to say to reason in third-person is to use a theory of mind to deduct how another person would reason. As a result I guess I’m using the term first-person and third-person in sense of everyday language rather than strict philosophical terminology. I appreciate this insight. Please forgive me in the following paragraphs as I will keep using the terms this way. Not because I don’t agree with you. Just that it makes writing easier.
My main argument is that from first-person perspectives there are unique perk/limitation not applicable to any body else. Such as one do not need any information to specify oneself, and one would always find oneself exists. If I bypass these perks and limitations then my reasoning would be meaningful to others in general. For example twins do not need to know their difference to tell themselves apart. But for everybody else differentiating them require knowing their difference. For the twin it is natural to ask how would others identify me without having to specify which exact person’s perspective among the “others” must he reason from to answer the question. Of course there is nothing wrong in specifying a third person either. In the sleeping beauty problem, we can take the experimenter’s perspective, an observer’s perspective, or even an imaginary person’s perspective, just that their reasoning would be the same. I am not trying to define third-person perspective as the unique perspective of an outside-the-universe observer. As you pointed out that would make uniquely identifying any individual near (if not completely) impossible. Even worse it would make identifying the reference class impossible as well. I feel this identification would ultimately fall back to immediacy to perception. As you suggested in the names case: spatiotemporally close. Which again showing that you are correct in saying all perspective are first-person.
In the case of perspective of a non-mind such as a camera. To be completely honest I feel I do not know enough to contribute an opinion. Coming from a civil engineering background philosophy is not my forte. It is already quite difficult for me to put these not so easily describable ideas down in a second language. Can we reason from the perspective of a camera? I want to say yes? Because we can imagine it has a mind and mind is a non-physical concept so there is no logical contradiction. But again my opinion probably don’t worth two cents. Just want to say that this part I don’t think can change the answer to doomsday argument or the sleeping beauty problem.
One note about terminology: there is no such thing as a third-person perspective. The central case of a perspective is a point or timeline in spacetime that things can be viewed from (see: perspective drawing). A more general notion of perspective is that of a set of nodes in a causal graph from which indexical references to other graph nodes can be defined. But in any case these perspectives are necessarily first-person, since they are from somewhere.
You could try to use the ontology of physics to define hypothetical perspectives on our universe that are outside of our universe, but once precisely defined, these would also be first-person, and defining these perspectives would be complicated by issues like defining objects and interpretations of quantum mechanics.
In the sleeping beauty problem, it is sensible to talk about the experimenter’s perspective, but not to talk about a non-specific third-person perspective.
(as one case of this: you talk of using names to address individuals from a third-person perspective. But, unless your names are really really long, this doesn’t work in a big universe if the third-person perspective is taken to be some perspective definable from physics, since there are more individuals than short names in a big universe. It does work if by “third-person perspective” you mean some first-person perspective, e.g. that of a member of a group or some intersubjective perspective formed from those of the group members, that needs to uniquely refer to each of some not-extremely-large number of individuals who are spaciotemporally close)
EDIT: just realized that “first-person” has the implication that the perspective is from some person, i.e. a kind of mind. But not all perspectives are from a mind (e.g. camera perspectives). They are still located in a particular place in a causal graph (such as spacetime), though.
I think you are correct that all perspectives are ultimately first-person. That’s why I had to say to reason in third-person is to use a theory of mind to deduct how another person would reason. As a result I guess I’m using the term first-person and third-person in sense of everyday language rather than strict philosophical terminology. I appreciate this insight. Please forgive me in the following paragraphs as I will keep using the terms this way. Not because I don’t agree with you. Just that it makes writing easier.
My main argument is that from first-person perspectives there are unique perk/limitation not applicable to any body else. Such as one do not need any information to specify oneself, and one would always find oneself exists. If I bypass these perks and limitations then my reasoning would be meaningful to others in general. For example twins do not need to know their difference to tell themselves apart. But for everybody else differentiating them require knowing their difference. For the twin it is natural to ask how would others identify me without having to specify which exact person’s perspective among the “others” must he reason from to answer the question. Of course there is nothing wrong in specifying a third person either. In the sleeping beauty problem, we can take the experimenter’s perspective, an observer’s perspective, or even an imaginary person’s perspective, just that their reasoning would be the same. I am not trying to define third-person perspective as the unique perspective of an outside-the-universe observer. As you pointed out that would make uniquely identifying any individual near (if not completely) impossible. Even worse it would make identifying the reference class impossible as well. I feel this identification would ultimately fall back to immediacy to perception. As you suggested in the names case: spatiotemporally close. Which again showing that you are correct in saying all perspective are first-person.
In the case of perspective of a non-mind such as a camera. To be completely honest I feel I do not know enough to contribute an opinion. Coming from a civil engineering background philosophy is not my forte. It is already quite difficult for me to put these not so easily describable ideas down in a second language. Can we reason from the perspective of a camera? I want to say yes? Because we can imagine it has a mind and mind is a non-physical concept so there is no logical contradiction. But again my opinion probably don’t worth two cents. Just want to say that this part I don’t think can change the answer to doomsday argument or the sleeping beauty problem.