Consider a conspiratorial interpretation of quantum mechanics according to which the universe is genuinely local and deterministic, but the initial conditions of the universe are jerry-rigged so that all measurements made by sentient creatures fit quantum statistics (even though events in general do not). This theory is empirically equivalent to many worlds. It seems clear that there are several senses in which it is not equivalent to many worlds. And I think there is good reason to assign it substantially lower prior probability than many worlds, since one would need to specify the entire initial condition of the universe in order to predict correlations that many worlds predicts based simply on Schrodinger’s equation.
That’s a useful demonstration of the intuition behind “simpler is more plausible”. Still, if it were possible to know that your jury-rigged-setup story were everywhere and always (not just up-til-now) empirically equivalent to MWI or whatever, then I’d really bite the bullet and call it absolutely equivalent.
Consider a conspiratorial interpretation of quantum mechanics according to which the universe is genuinely local and deterministic, but the initial conditions of the universe are jerry-rigged so that all measurements made by sentient creatures fit quantum statistics (even though events in general do not). This theory is empirically equivalent to many worlds. It seems clear that there are several senses in which it is not equivalent to many worlds. And I think there is good reason to assign it substantially lower prior probability than many worlds, since one would need to specify the entire initial condition of the universe in order to predict correlations that many worlds predicts based simply on Schrodinger’s equation.
That’s a useful demonstration of the intuition behind “simpler is more plausible”. Still, if it were possible to know that your jury-rigged-setup story were everywhere and always (not just up-til-now) empirically equivalent to MWI or whatever, then I’d really bite the bullet and call it absolutely equivalent.
Fair enough. Incidentally, if you’re looking for a rigorous justification of Occam’s razor, the best one I know of is Kevin Kelly’s.