Many worlds is not positing any old Descartes' demon though. It's just a trivial combination of things that are considered obvious.
1. Wavefunctions and superpositions objectively exist.
2. Wavefunctions can be entangled with each other, in ways that make parts of them not interact with each other.
3. When interactions have differing outcomes given different parts of a superposition, you find the outcomes depend on a single part of said superposition.
If you posit the exact same rules for the lab as the experiment, 'wavefunction collapse' or 'communication' aren't even concepts that apply 3 becomes tautilogical. The only questions are 1. 'why do I find myself observing the world as the experimenter who saw A and not the experimenter who saw B', but the other you is asking the exact same question, and you'll never encounter them. And 2. what is entropy/measurement/why do I observe the world as one experimenter and not both?
Superdeterminism goes the other way and throws out free will, information, and randomness. If you do that, you're left with equally large questions about why entropy increases, what is information, and why do we think we have free will? It's a fairly large philosophical step backwards low information explanations for many things have to be replaced with 'just because the universe is arranged precisely in a way that makes it seem that way even though there's no reason it couldn't be arranged differently'
Both are far more coherent and less egotistical than copenhagen or bohmian mechanics.
1. Wavefunctions and superpositions objectively exist.
2. Wavefunctions can be entangled with each other, in ways that make parts of them not interact with each other.
3. When interactions have differing outcomes given different parts of a superposition, you find the outcomes depend on a single part of said superposition.
If you posit the exact same rules for the lab as the experiment, 'wavefunction collapse' or 'communication' aren't even concepts that apply 3 becomes tautilogical. The only questions are 1. 'why do I find myself observing the world as the experimenter who saw A and not the experimenter who saw B', but the other you is asking the exact same question, and you'll never encounter them. And 2. what is entropy/measurement/why do I observe the world as one experimenter and not both?
Superdeterminism goes the other way and throws out free will, information, and randomness. If you do that, you're left with equally large questions about why entropy increases, what is information, and why do we think we have free will? It's a fairly large philosophical step backwards low information explanations for many things have to be replaced with 'just because the universe is arranged precisely in a way that makes it seem that way even though there's no reason it couldn't be arranged differently'
Both are far more coherent and less egotistical than copenhagen or bohmian mechanics.