It means that if in your branch you are the first one to whistle the tune, there is no one else in your branch to contradict you. (Just as you would expect in One World.) In some other branch someone else was first, and in that branch you don’t think that you were the first, so again no conflict.
if my normal is Newtonian physics
Then “adding up to normal” means that even when Einstein ruins your model, all things will behave the same way as they always did. Things that within given precision obeyed the Newtonian physics, will continue to do it. You will only see exceptions in unusual situations, such as GPS satellites. (But if you had GPS satellites before Einstein invented his theory, you would have seen those exceptions too. You just didn’t know that would happen.)
In case of morality it means that if you had a rule “X is good” because it usually has good consequences (or because it follows the rules, or whatever), then “X is good” even with Many Worlds. The exception is if you try to apply moral significance to a photon moving through a double slit.
An explanation may change: for example it was immoral to say “if the coin ends this side up, I will kill you”, and it is still immoral to do so, but the previous explanation was that “it is bad to kill people with 50% probability” and the new explanation is “it is bad to kill people in 50% of branches” (which means killing them with 50% probability in a random branch).
Okay, so on reflection, I think the idea that it all adds up to normality is just junk. It doesn’t mean anything. I’ll try to explain:
A: MW comes into conflict with this ethical principle.
B: It can’t come into conflict. Physics always adds up to normality.
A: Really? Suppose I see an apple falling, and you discover that there’s no such thing as an apple, but that what we called apples are actually a sub-species of blueberries. Now I’ve learned that I’ve in fact never seen an apple fall, since by ‘apple’ I meant the fruit of an independent species of plant. So, normality overturned.
B: No, that’s not an overturning of normality, that’s just a change of explanation. What you saw was this greenish round thing falling, and you explained this as an ‘apple’. Now your explanation is different, but the thing you observed is the same.
A: Ah, but lets say science discovers that the green round thing I saw isn’t green at all. In fact, green is just the color that bounces off the thing. If it’s any color, it’s the color of the wavelengths of light it absorbs. Normality overturned.
B: But that’s just what being ‘green’ now means. What you saw was some light your receptors in way that varied over time, and you explained this as a green thing moving. The observation, the light hitting your eye over time, is the same. The explanation has shifted.
A: Now say that it turns out that (bear with me) there is no motion or time. What I thought was some light hitting my retina over time is just my own brain co-evolving with a broader wave-function. Now that’s overturning normality.
B: No, what you experienced qualitatively is the same, but the explanation has changed.
A: What did I experience qualitatively?
B: If you’re willing to go into plausible but hypothetical discoveries, I can’t give it any description that is basic enough that it can’t be ‘overturned’. Even ‘experience’ is probably overturnable.
A: That’s why ‘it all adds up to normality’ is junk. By that standard, nothing is normal. If anything I can describe as a phenomenon is normal, then it can be overturned under that description.
It means that if in your branch you are the first one to whistle the tune, there is no one else in your branch to contradict you. (Just as you would expect in One World.) In some other branch someone else was first, and in that branch you don’t think that you were the first, so again no conflict.
Then “adding up to normal” means that even when Einstein ruins your model, all things will behave the same way as they always did. Things that within given precision obeyed the Newtonian physics, will continue to do it. You will only see exceptions in unusual situations, such as GPS satellites. (But if you had GPS satellites before Einstein invented his theory, you would have seen those exceptions too. You just didn’t know that would happen.)
In case of morality it means that if you had a rule “X is good” because it usually has good consequences (or because it follows the rules, or whatever), then “X is good” even with Many Worlds. The exception is if you try to apply moral significance to a photon moving through a double slit.
An explanation may change: for example it was immoral to say “if the coin ends this side up, I will kill you”, and it is still immoral to do so, but the previous explanation was that “it is bad to kill people with 50% probability” and the new explanation is “it is bad to kill people in 50% of branches” (which means killing them with 50% probability in a random branch).
Okay, so on reflection, I think the idea that it all adds up to normality is just junk. It doesn’t mean anything. I’ll try to explain:
A: MW comes into conflict with this ethical principle.
B: It can’t come into conflict. Physics always adds up to normality.
A: Really? Suppose I see an apple falling, and you discover that there’s no such thing as an apple, but that what we called apples are actually a sub-species of blueberries. Now I’ve learned that I’ve in fact never seen an apple fall, since by ‘apple’ I meant the fruit of an independent species of plant. So, normality overturned.
B: No, that’s not an overturning of normality, that’s just a change of explanation. What you saw was this greenish round thing falling, and you explained this as an ‘apple’. Now your explanation is different, but the thing you observed is the same.
A: Ah, but lets say science discovers that the green round thing I saw isn’t green at all. In fact, green is just the color that bounces off the thing. If it’s any color, it’s the color of the wavelengths of light it absorbs. Normality overturned.
B: But that’s just what being ‘green’ now means. What you saw was some light your receptors in way that varied over time, and you explained this as a green thing moving. The observation, the light hitting your eye over time, is the same. The explanation has shifted.
A: Now say that it turns out that (bear with me) there is no motion or time. What I thought was some light hitting my retina over time is just my own brain co-evolving with a broader wave-function. Now that’s overturning normality.
B: No, what you experienced qualitatively is the same, but the explanation has changed.
A: What did I experience qualitatively?
B: If you’re willing to go into plausible but hypothetical discoveries, I can’t give it any description that is basic enough that it can’t be ‘overturned’. Even ‘experience’ is probably overturnable.
A: That’s why ‘it all adds up to normality’ is junk. By that standard, nothing is normal. If anything I can describe as a phenomenon is normal, then it can be overturned under that description.