You are decreasing the amount of that person that exists.
Yes, there is a measure of that person’s existence (number of perfect copies) which I’m reducing by deleting a perfect copy of that person. What I’m saying is precisely that I don’t care, because that is not a measure of people I value.
Similarly, if I gain 10 pounds, there’s a measure of my existence (mass) which I thereby increase. I don’t care, because that’s not a measure of people I value.
Neither of those statements is quite true, admittedly. For example, I care about gaining 10 pounds because of knock-on effects—health, vanity, comfort, etc. I care about gaining an identical backup because of knock-on effects—reduced risk of my total destruction, for example. Similarly, I care about gaining a million dollars, I care about gaining the ability to fly, there’s all kinds of things that I care about. But I assume that your point here is not that identical copies are valuable in some sense, but that they are valuable in some special sense, and I just don’t see it.
As far as MWI goes, yes… if you posit a version of many-worlds where the various branches are identical, then I don’t care if you delete half of those identical branches. I do care if you delete me from half of them, because that causes my loved ones in those branches to suffer… or half-suffer, if you like. Also, because the fact that those branches have suddenly become non-identical (since I’m in some and not the others) makes me question the premise that they are identical branches.
Yes, there is a measure of that person’s existence (number of perfect copies) which I’m reducing by deleting a perfect copy of that person. What I’m saying is precisely that I don’t care, because that is not a measure of people I value.
Similarly, if I gain 10 pounds, there’s a measure of my existence (mass) which I thereby increase. I don’t care, because that’s not a measure of people I value.
Neither of those statements is quite true, admittedly. For example, I care about gaining 10 pounds because of knock-on effects—health, vanity, comfort, etc. I care about gaining an identical backup because of knock-on effects—reduced risk of my total destruction, for example. Similarly, I care about gaining a million dollars, I care about gaining the ability to fly, there’s all kinds of things that I care about. But I assume that your point here is not that identical copies are valuable in some sense, but that they are valuable in some special sense, and I just don’t see it.
As far as MWI goes, yes… if you posit a version of many-worlds where the various branches are identical, then I don’t care if you delete half of those identical branches. I do care if you delete me from half of them, because that causes my loved ones in those branches to suffer… or half-suffer, if you like. Also, because the fact that those branches have suddenly become non-identical (since I’m in some and not the others) makes me question the premise that they are identical branches.