Before, you were comparing a(n apparently) possible universe in which you do one thing, with an actual universe in which you do something else. These are not universes with no material differences.
But now you want me to imagine two otherwise identical worlds, one actual and one merely possible. This seems doubtfully coherent to me in two different ways. First, I am not at all sure it actually makes sense to distinguish between an imagined imaginary world and am imagined actual world: both, in fact, are merely imagined. Second and worse, if some possible world is identical to the actual world term I say it is in fact the actual world.
How you get from there to needing to choose between “vital energy” and modal realism, I don’t understand; it seems to me that if any theory is in need of such “vital energy” (which I’m not at all sure if the case) then it’s modal realism. And the thing you say is the “price” of modal realism seems to me obviously innocuous. Indeed, the most obvious way to try to implement something like modal realism is Everett quantum mechanics—which comes automatically with exactly the kind of measure you’re talking about.
Saying that your imagined possible-you who goes home by a different route is a figment of your imagination doesn’t contradict the mathematical universe hypothesis; it just means declining to identify the constructs of your imagination with portions of the (hypothetical) mathematical universe. When you say “of course I could have gone home the other way” on the basis that it just seems obvious, you are not identifying a portion of the Tegmark universe, you’re just indulging in imagination. (For the avoidance of doubt, there’s nothing wrong with that.)
I’m not sure that the counterfactual mugging thought experiment exactly shows that you have to do anything in particular, but by all means take into account possible or ways you could behave—but doing so really doesn’t have the exotic metaphysical commitments you seem to be claiming it has.
Before, you were comparing a(n apparently) possible universe in which you do one thing, with an actual universe in which you do something else. These are not universes with no material differences.
But now you want me to imagine two otherwise identical worlds, one actual and one merely possible. This seems doubtfully coherent to me in two different ways. First, I am not at all sure it actually makes sense to distinguish between an imagined imaginary world and am imagined actual world: both, in fact, are merely imagined. Second and worse, if some possible world is identical to the actual world term I say it is in fact the actual world.
How you get from there to needing to choose between “vital energy” and modal realism, I don’t understand; it seems to me that if any theory is in need of such “vital energy” (which I’m not at all sure if the case) then it’s modal realism. And the thing you say is the “price” of modal realism seems to me obviously innocuous. Indeed, the most obvious way to try to implement something like modal realism is Everett quantum mechanics—which comes automatically with exactly the kind of measure you’re talking about.
Saying that your imagined possible-you who goes home by a different route is a figment of your imagination doesn’t contradict the mathematical universe hypothesis; it just means declining to identify the constructs of your imagination with portions of the (hypothetical) mathematical universe. When you say “of course I could have gone home the other way” on the basis that it just seems obvious, you are not identifying a portion of the Tegmark universe, you’re just indulging in imagination. (For the avoidance of doubt, there’s nothing wrong with that.)
I’m not sure that the counterfactual mugging thought experiment exactly shows that you have to do anything in particular, but by all means take into account possible or ways you could behave—but doing so really doesn’t have the exotic metaphysical commitments you seem to be claiming it has.