That seems to me to be a superposition of two different arguments.
There’s a philosophy-of-science claim that any theory that isn’t obviously wrong must be compatible with all observations to date.
And there’s a kind of normative claim that you shouldn’t change your behaviour a lot when you switch from one ontology to another.
The sameness of predicted observations is just the sameness of predicted observation, not everything. Interpretations of quantum mechanics, to be taken seriously, must agree on the core set of observations, but they can and do vary in their ontological implications. They have to differ about something., or they wouldn’t be different interpretations.
But it is entirely possible for ethics to vary with ontology. It is uncontroversial that the possibility of free will impacts ethics, at the theoretical level. Why shouldn’t the possibility of many worlds?
Oh no, then there are always copies of me doing terrible things, and so none of my choices matter!
May not be necessarily true, but it is not necessarily false. It is not absurd, it is a reasonable thing to worry about … at the theoretical level.
But that doesn’t contradict the other version of “it all adds up to normality”, because that claim is a piece of practical advice. Although it seems possible for deep theoretical truths of metaphysics to impact ethics, the connection is to complex and doubtful to be allowed to affect day-to-day behaviour.
That seems to me to be a superposition of two different arguments.
There’s a philosophy-of-science claim that any theory that isn’t obviously wrong must be compatible with all observations to date.
And there’s a kind of normative claim that you shouldn’t change your behaviour a lot when you switch from one ontology to another.
The sameness of predicted observations is just the sameness of predicted observation, not everything. Interpretations of quantum mechanics, to be taken seriously, must agree on the core set of observations, but they can and do vary in their ontological implications. They have to differ about something., or they wouldn’t be different interpretations.
But it is entirely possible for ethics to vary with ontology. It is uncontroversial that the possibility of free will impacts ethics, at the theoretical level. Why shouldn’t the possibility of many worlds?
May not be necessarily true, but it is not necessarily false. It is not absurd, it is a reasonable thing to worry about … at the theoretical level.
But that doesn’t contradict the other version of “it all adds up to normality”, because that claim is a piece of practical advice. Although it seems possible for deep theoretical truths of metaphysics to impact ethics, the connection is to complex and doubtful to be allowed to affect day-to-day behaviour.