How do you know that they are the ones who are being irrational here, and not you?
This is a serious question. We should always challenge our preconceptions. To take your examples:
1. Traditional Judeo-Christian religions all claim we should believe because of claims made in holy books of questionable provenance, held by primitive people who believed things like (for example) disease being caused by demons. What rational reason is there for believing these holy books to be particularly truthful? (I was careful to not include Buddhism, whose basis is in experiences that people have while in altered states of consciousness from meditation.)
2. The shortcomings of libertarianism involve various tragedies of the commons. (My favorite book on this being, The Logic of Collective Action.) However the evidence in favor of most government interventions is rather weak. And the evidence is very strong that well-intended government interventions predictably will, after regulatory capture, wind creating severe problems of their own. How do you know that the interventions which you like will actually lead to good results? (Note, both major US parties are uneasy coalitions of convenience kept together through the only electoral realities of winner takes all. On the left, big labor and environmentalism are also uncomfortable bedfellows.)
3. To the extent that the observer is described by quantum mechanics, many-worlds is provably a correct description of the process of observation. In the absence of concrete evidence that quantum mechanics breaks down for observers like us, what rational reason is there to advocate for any other interpretation? (The fact that it completely violates our preconceptions about how the world should work is an emotional argument, not a rational one.)
I kind of intended that comment to be ironic self-deprecating humor because, of course, I have no way of knowing whether or not I'm being irrational. Irrational people think they're rational, and so the fact that I think I'm rational does not mean that I am. But it's likewise for everyone. The real point is that everyone ought to have a little more humility about their own rationality (especially all the idiots who are downvoting my original comments. Now they are being totally irrational!)
I read it, but from it you seem to be making three points.
1. Many worlds is indeed what QM predicts should happen.
2. Popular descriptions are oversimplified and the full explanation is very complicated.
3. Even if many worlds is true, it doesn't change my experience and should not rationally change how I act when faced with quantum uncertainty.
If I am correct, then I'm in violent agreement with all three points. And am left with, "So until more data, I will provisionally accept many worlds as the best explanation."
My impression is that you seem to be left with, "If it is true, then it is irrelevant to my life, and so I don't care about whether it might be true."
> Many worlds is indeed what QM predicts should happen.
No. Many-worlds is what the SE predicts should happen. But the SE != QM. MW does not explain the Born rule, which is part of QM's predictions. MW is also violently at odds with subjective experience. So MW is not a good explanation of what is observed.
Let's weaken it slightly. Consider Schrödinger's cat. Let's assume the Copenhagen interpretation, and assume that collapse does not happen until the box is opened.
Now let's modify the experiment to assume a hyper-intelligent cat, with access to a full physics laboratory inside of the box.
QM predicts that there is no experiment that is possible for the cat to conduct that can tell whether collapse happened. The QM description of what's going on in the box is guaranteed to be alien to the cat's experience, but perfectly predicts what the cat does experience. Furthermore, even though in this hypothetical, collapse happens when the box is opened, there is no experiment that can be done by the outside experimenter which can verify that collapse happened when the box opened, and not before. Nor is there any experiment that the experimenter can perform that confirms that collapse does not happen afterwards.
And yes, this includes attempts by the cat to confirm the Born rule. As far as the cat can determine, the Born rule will be true.
Therefore our assumption in this hypothetical that QM describes the cat leads to MW being true for the cat no matter what is ultimately true.
And this is what I mean by saying that, to the extent that the experimenter is described by QM, MW is true.
As for the differences between Convivial Solipsism and Many Worlds, I am indifferent to them. It is immaterial to me whether I am a singular observer who can only be aware of part of the wave function, or I am one component of a superposition of observers, each of which is only aware of part of the wave function.
I personally lean away from solipsism because I do not think that I, or my observation of reality, are that important. But that is a preference. And I don't have any particular justification for it or reason to disagree with anyone with the opposite opinion.
One thing I'm curious about: I haven't read the literature all that well, but my personal understanding of MWI, after trying to wrap my head around it, is that there's probably no branching or peeling at all: every possible configuration of the universe immutably exists and is associated with a complex amplitude. What does change are the amplitudes. When I make a choice at point A and the universe "splits" into B and C, the only thing that happens is that the amplitude in bucket A is split into buckets B and C. But there's no reason to think A, B and C were ever empty or will ever be empty: after all, some other state Z might pour amplitude into A at the same time A pours into B and C. We might even currently be in a steady state where the universal wavefunction is perfectly static, because every single "branch" is perfectly compensated by a "join". If so, MWI would challenge the very idea that existence is a binary predicate (it's actually a continuous complex amplitude). I'm honestly not sure how we're even supposed to reason about that thing.
This is a serious question. We should always challenge our preconceptions. To take your examples:
1. Traditional Judeo-Christian religions all claim we should believe because of claims made in holy books of questionable provenance, held by primitive people who believed things like (for example) disease being caused by demons. What rational reason is there for believing these holy books to be particularly truthful? (I was careful to not include Buddhism, whose basis is in experiences that people have while in altered states of consciousness from meditation.)
2. The shortcomings of libertarianism involve various tragedies of the commons. (My favorite book on this being, The Logic of Collective Action.) However the evidence in favor of most government interventions is rather weak. And the evidence is very strong that well-intended government interventions predictably will, after regulatory capture, wind creating severe problems of their own. How do you know that the interventions which you like will actually lead to good results? (Note, both major US parties are uneasy coalitions of convenience kept together through the only electoral realities of winner takes all. On the left, big labor and environmentalism are also uncomfortable bedfellows.)
3. To the extent that the observer is described by quantum mechanics, many-worlds is provably a correct description of the process of observation. In the absence of concrete evidence that quantum mechanics breaks down for observers like us, what rational reason is there to advocate for any other interpretation? (The fact that it completely violates our preconceptions about how the world should work is an emotional argument, not a rational one.)