Yes, this is another way of going about it (I said there were more than one way of doing it :-)
The other case that I haven’t yet considered is when you start with two identical copies, that then get different inputs (so moving more towards a situation like in model 3). And if you don’t use SIA, then your probabilities will be time-inconsistent (though you will still get the right answer!). That’s why I tend to prefer SIA+division of responsibility, because the probabilities of being in a world doesn’t change according to irrelevant information.
Yes, this is another way of going about it (I said there were more than one way of doing it :-)
The other case that I haven’t yet considered is when you start with two identical copies, that then get different inputs (so moving more towards a situation like in model 3). And if you don’t use SIA, then your probabilities will be time-inconsistent (though you will still get the right answer!). That’s why I tend to prefer SIA+division of responsibility, because the probabilities of being in a world doesn’t change according to irrelevant information.