Let’s check: “I can only have preferences over things that exist. The ship probably exists, because my memory of its departure is evidence. The parallel worlds have no similar evidence for their existence.” Is that correct paraphrasing?
No, not really. I mean, it’s not that far from something I said, but it’s departing from what I meant and it’s not in any case the point of my reply. The mistake I’m making is persisting in trying to clarify a particular way of viewing the problem which is not the best way and which is leading us both down the garden path. Instead, please forget everything else I said and consider the following argument.
Theories have two aspects. Testable predictions, and descriptive elements. I would (and I think the sequences support me) argue that two theories which make the same predictions are not different theories, they are the same theory with different flavour. In particular, you should never make a different decision under one theory than under the other. Many Worlds is a flavour of quantum mechanics, and if that choice of flavour effects ethical decisions then you are making different decisions according to the flavour rather than content of the theory, and something has gone wrong.
Everything else I said was intended solely to support that point, but somewhere along the way we got lost arguing about what’s observable, what consitutes evidence and meta-ethics. If you accept that argument then I have no further point to make. If you do not accept it, then please direct comments at that argument directly rather than anything else I’ve said.
I’ll try to address the rest of your reply with this in mind in the hopes that it’s helpful.
If … your interpretation of those laws involves Many Worlds
You could equally have said “If your interpretation of the physics of raindrops involves fairies”. My point is that no-one has any justification for making that assumption. Quantum physics is a whole bunch of maths that models the behaviour of particles on a small scale. Many Worlds is one of many possible descriptions of that maths that help us understand it. If you arbitrarily assume your description is a meaningful property of reality then sure, everything else you say follows logically, but only because the mistake was made already.
You compare Many Worlds to fairies in the wrong place, in particular post-arbitrary-assumption for Many Worlds and pre-arbitrary-assumption for fairies. I’ll give you the analogous statements for a correct comparison:
the Faeries do not merit consideration because it is impossible to get evidence for their existence
The people of other worlds do not merit consideration because it is impossible to get evidence of their existance.
if we except Many Worlds...
If we accept fairies...
… the memory of the existence of a quantum bomb is evidence that there exist many branches with Other Worlds in which everyone was wiped out by the bomb
… the sight of a raindrop falling is evidence that there exists a fairy a short distance away.
Taboo “justification”. Justification is essentially a pointer to evidence or inference. After all the inference is said and done, the person who needs to provide more evidence is the person who has the more un-parsimonious hypothesis. You reject fairies based on a lack of justification because it’s not parsimonious. You can’t reject Many-Worlds on those same grounds, at least not without explaining more.
The difference is that the fairies interpretation of raindrops has different maths than the non-fairy interpretation of raindrops. When the mathematically-rigorous descriptions for two different hypotheses are different, there is a clear correct answer as to which is more parsimonious.
Many-worlds has exactly the same mathematical description as the alternative, so it’s hard to say which is more parsimonious. You can’t say that Single-World is default and Many Worlds requires justification. This is why I claim that it is first a question of ontology (a question of what we choose to define as reality), and then maybe we can talk about the epistemology and whether or not the statement is “True” within our definitions...after we clarify our ontology and define the relationship between ontology and parsimony, not before.
No, not really. I mean, it’s not that far from something I said, but it’s departing from what I meant and it’s not in any case the point of my reply. The mistake I’m making is persisting in trying to clarify a particular way of viewing the problem which is not the best way and which is leading us both down the garden path. Instead, please forget everything else I said and consider the following argument.
Theories have two aspects. Testable predictions, and descriptive elements. I would (and I think the sequences support me) argue that two theories which make the same predictions are not different theories, they are the same theory with different flavour. In particular, you should never make a different decision under one theory than under the other. Many Worlds is a flavour of quantum mechanics, and if that choice of flavour effects ethical decisions then you are making different decisions according to the flavour rather than content of the theory, and something has gone wrong.
Everything else I said was intended solely to support that point, but somewhere along the way we got lost arguing about what’s observable, what consitutes evidence and meta-ethics. If you accept that argument then I have no further point to make. If you do not accept it, then please direct comments at that argument directly rather than anything else I’ve said.
I’ll try to address the rest of your reply with this in mind in the hopes that it’s helpful.
You could equally have said “If your interpretation of the physics of raindrops involves fairies”. My point is that no-one has any justification for making that assumption. Quantum physics is a whole bunch of maths that models the behaviour of particles on a small scale. Many Worlds is one of many possible descriptions of that maths that help us understand it. If you arbitrarily assume your description is a meaningful property of reality then sure, everything else you say follows logically, but only because the mistake was made already.
You compare Many Worlds to fairies in the wrong place, in particular post-arbitrary-assumption for Many Worlds and pre-arbitrary-assumption for fairies. I’ll give you the analogous statements for a correct comparison:
The people of other worlds do not merit consideration because it is impossible to get evidence of their existance.
If we accept fairies...
… the sight of a raindrop falling is evidence that there exists a fairy a short distance away.
Taboo “justification”. Justification is essentially a pointer to evidence or inference. After all the inference is said and done, the person who needs to provide more evidence is the person who has the more un-parsimonious hypothesis. You reject fairies based on a lack of justification because it’s not parsimonious. You can’t reject Many-Worlds on those same grounds, at least not without explaining more.
The difference is that the fairies interpretation of raindrops has different maths than the non-fairy interpretation of raindrops. When the mathematically-rigorous descriptions for two different hypotheses are different, there is a clear correct answer as to which is more parsimonious.
Many-worlds has exactly the same mathematical description as the alternative, so it’s hard to say which is more parsimonious. You can’t say that Single-World is default and Many Worlds requires justification. This is why I claim that it is first a question of ontology (a question of what we choose to define as reality), and then maybe we can talk about the epistemology and whether or not the statement is “True” within our definitions...after we clarify our ontology and define the relationship between ontology and parsimony, not before.