I agree with Unnamed that this post misunderstands Parfit’s argument by tying it empirical claims about resources that have no relevance.
My argument was against the Mere Addition Paradox, which works by progressively adding more and more people, and the common belief that one of the implications of the MAP is that we have a moral duty to devote all our resources to creating extremely large amounts people.
My main goal is to integrate the common intuition that A+ is better than A with the intuition that creating a vast number of people with low quality of life is bad. Parfit supports the intuition that A+ is better than A by pointing out that the extra people are not doing the inhabitants of A any harm by existing. I point out the reason that this is true is that the extra inhabitants come with their own resources, and that a society with those extra resources, but less people (A++), would be even better.
Just imagine God is offering you choices between different universes with inhabitants of the stipulated level of wellbeing: he offers you A, then offers you to take A+, then B, then B+, etc.
If each world had the same amount of resources then I’d choose A, it’s the most efficient one at converting resources into overall value.
My understanding of Parfit’s point is that it let you argue that all other things being equal, a huge population with low quality of life is better than a small one with high quality of life. This is what I am trying to refute. Like Unnamed, you don’t seem to think this is necessarily what the MAP implies.
This is what the repugnant conclusion is all about: it has nothing whatsoever to do with whether or not Z (or the ‘mechanism’ of mere addition to get from A to Z) is feasible under resource constraint, but that if this were possible, maximizing aggregate value obliges we take this repugnant conclusion. I don’t want to be mean, but this is a really basic error.
Again, my main point in writing this was to attack the chain of logic that leads from the intuition that adding a few people to A+ will do no harm to the Repugnant Conclusion. In other words, to attack the paradoxical nature of the MAP. I am aware that there are other arguments for the RC that require other responses such as the one about maximizing aggregate utility. Would you buy those cable packages if the government wasn’t forcing you to?
Perhaps I should have started with the pluralist values, since they were sort of the underpinning of my argument. I am basically advocating a system where both creating new lives worth living, improving the utility of those who exist, and possibly other values such as equality, contribute to Overall Value. However, they have diminishing returns relative to each other (if saying that the value of creating a life worth living changes gives you the creeps just keep the value of doing that constant and change the value of the others, it’s essentially the same). I’m not sure if increasing total utility should be a contributing value on its own, or if it is just a side-effect of increasing both the number of lives worth living and the average utility simultaneously.
So the more lives worth living you have, the greater the contributions that enhancing the utility existing lives contributes to overall value. For instance, in a very small population using resources to create a life worth living might contribute 1 Overall Value Point (OVP) while using those same resources to improve existing lives might only produce 0.5 OVPs. However, as the population grows larger, improving existing lives generates more and more OVPs, while creating lives worth living shrinks or remains constant.*
So maybe, if you added a vast amount of lives worth living to a you could generate the same amount of OVP that you could by increasing the average utility just a little. But it would be a fantastically inefficient way to generate OVP. A world where some of the resources used to sustain all those lives were instead used to enhance the lives of those who already exist would be a world with vastly more overall value.
Given the ‘average term’ doesn’t dominate (or is lexically prior to) the total utility term, there will be acceptable deals this average total pluralist should accept where we lose some average but gain more than enough total utility to make up for it.
Is this any different from the Zeno’s paradoxes of motion? I.E. you’re basically saying that there is no point where the changes are big enough to become undesirable, so eventually we’ll get to a point that everyone agrees is undesirable. How is that any different from saying Achilles will never catch the tortoise?
*I imagine that actually the values might also change relative to the resources available. Having 8 billion lives worth living on one planet seems like a good amount, but having just 8 billion lives worth living in a whole galaxy seems like a waste.
1) I don’t think anyone in the entire population ethics literature reads Parfit as you do: the moral problem is not one of feasibility via resource constraint, but rather just that Z is a morally preferable state of affairs to A, even if it is not feasible. Again, the paradoxical nature of the MAP is not harmed even if it demands utterly infeasible or even nomologically impossible, but that were we able to actualize Z we should do it.
Regardless, I don’t see how the ‘resource constraint complaint’ you make would trouble the reading of Parfit you make. Parfit could just stipulate that the ‘gain’ in resources required from A to A+ is just an efficiency gain, and so A → Z (or A->B, A->Z) does not involve any increase in consumption. Or we could stipulate the original population in A, although giving up some resources are made happier by knowing there is this second group of people, etc. etc. So it hardly seems necessarily the case that A to A+ demands increased consumption. Denying these alternatives looks like hypothetical fighting.
2) I think the pluralist point stands independently of the resource constraint complaint. But you seem imply a fact you value efficient resource consumption independently: you prefer A because it is a more efficient use of resources, you note there might be diminishing returns to the value of ‘added lives’ so adding lives becomes a merely inefficient way of adding value, etc. Yet I don’t think we should care about efficiency save as an instrument of getting value. All things equal a world with 50 Utils burning 2 million utils is better than one with 10 utils burning 10. So (again) objections to feasibility or efficiency shouldn’t harm the MAP route to the repugnant conclusion.
3) I take your hope for escaping the MAP is getting some sort of weighted sum or combination of total utility, the utility of those who already exist, and possibly average utility of lives will get us our ‘total value’. However, unless you hold that the ‘average term’ or the ‘person affecting’ term are lexically prior to utility (so no amount of utility can compensate for a drop in either), you are still susceptible to a variant of the MAP I gave above:
A : 10 people at wellbeing 10 A+: 10 People at wellbeing 20 & 1 million at wellbeing 9.5 B: 1 million and ten people at wellbeing 9.8.
So the A to A+ move has a small drop in average but a massive gain in utility, and persons already existing gain a boost in their wellbeing (and I can twist the dials even more astronomically). So if we can add these people, redistributing between them such that total value and equality increases seems plausible. And so we’re off to the races. It might be the case that each move demands arbitrarily massive (and inefficient) use resources to actualize—but, again, this is irrelevant to a moral paradox. The only way the diminishing marginal returns point would help avoid MAP if they were asymptotic to some upper bound. However, cashing things out that way looks implausible, and also is vulnerable to intransitivity.
I don’t see the similarity to Zeno’s paradoxes of motion—or, at least, I don’t see how this variant is more similar to Zeno than the original MAP is. Each step from A to A+ to B …. to Z, either originally or in my variant to make life difficult for your view is a step that increases total value. Given transitivity, Z will be better than A. If you think this is unacceptably Zeno like, then you could just make that complaint to the MAP simpliciter (although, FWIW, I think there are sufficient disanalogies as Zeno only works by taking each ‘case’ asymptotically closer to the singularity when tortoise and achilles meet, by contrast MAP is expanding across relevant metrics, so it seems more analogous to a Zeno case where Achilles is ahead of the Tortoise).
I don’t think anyone in the entire population ethics literature reads Parfit as you do: the moral problem is not one of feasibility via resource constraint, but rather just that Z is a morally preferable state of affairs to A, even if it is not feasible.
The view I am criticizing is not that Z may be preferable to A, under some circumstances. It is the view that if the only ways Z and A differ is that Z has a higher population, and lower quality of life, then Z is preferable to A. This may not be how Parfit is correctly interpreted, but it is a common enough interpretation that I think it needs to be attacked.
Again, the paradoxical nature of the MAP is not harmed even if it demands utterly infeasible or even nomologically impossible, but that were we able to actualize Z we should do it.
Again, my complaint with the paradox is not that, if Z and A are our only choices, that A is preferable to Z. Rather my complaint is the interpretation that if we were given some other alternative, Y that has a much larger population than A, but a smaller population and higher quality of life than Z, that Z would be preferable to Y as well.
All things equal a world with 50 Utils burning 2 million utils is better than one with 10 utils burning 10. So (again) objections to feasibility or efficiency shouldn’t harm the MAP route to the repugnant conclusion.
Again, I admitted that my solution might allow a MAP route to the repugnant conclusion under some instances like the one you describe. My main argument is that under circumstances where our choices are not constrained in such a manner, it is better to pick a society with a higher quality of life and lower population.
So the A to A+ move has a small drop in average but a massive gain in utility, and persons already existing gain a boost in their wellbeing (and I can twist the dials even more astronomically). So if we can add these people, redistributing between them such that total value and equality increases seems plausible. And so we’re off to the races. It might be the case that each move demands arbitrarily massive (and inefficient) use resources to actualize—but, again, this is irrelevant to a moral paradox.
Again, my objection is not that going this route is preferable is the best choice if it is the only choice we are allowed. My objection is to people who interpret Parfit to mean that even under circumstances where we are not in such a hypothetical and have more option to choose from, we should still choose the world with lives barely worth living (i.e. Robin Hanson). Again, those people may be interpreting Parfit incorrectly, which in turn makes my criticism seem like an incorrect interpretation of Parfit. But I think it is a common enough view that it deserves criticism.
In light of your and Unnamed’s comments I have edited my post and added an explanatory paragraph at the beginning, which says:
“EDIT: To make this clearer, the interpretation of the Mere Addition Paradox this post is intended to criticize is the belief that two societies that differ in no way other than that one has a higher population and lower quality of life than the other, that that society is necessarily better than the one with the lower population and higher quality of life. Several commenters have argued that this is not a correct interpretation of the Mere Addition Paradox. They seem to claim that a more correct interpretation is that a sufficiently large population with a lower quality of life is better than a smaller one with a higher quality of life, but that it may need to differ in other ways (such as access to resources) to be truly better. They may be right, but I think that it is still a common enough interpretation that it needs attacking. The main practical difference between the interpretation that I am attacking and the interpretation they hold is that the former confers a moral obligation to create as many people as possible, regardless of its effects on quality of life, but the later does not.”
Let me know if that deals sufficiently with your objections.
″ It is the view that if the only ways Z and A differ is that Z has a higher population, and lower quality of life, then Z is preferable to A. This may not be how Parfit is correctly interpreted, but it is a common enough interpretation that I think it needs to be attacked.”
Generally it’s a good idea to think twice and reread before assuming that a published and frequently cited paper is saying something so obviously stupid.
Your edit doesn’t help much at all. You talk about what others “seem to claim”, but the argument that you have claimed Parfit is making is so obviously nonsensical, that it would lead me to wonder why anyone cites his paper at all, or why any philosophers or mathematicians have bothered to refute or support it’s conclusions with more than a passing snark. A quick google search on the term “Repugnant Conclusion” leads to a wikipedia page that is far more informative than anything you have written here.
Generally it’s a good idea to think twice and reread before assuming that a published and frequently cited paper is saying something so obviously stupid.
It doesn’t seem any less obviously stupid to me then the more moderate conclusion you claim that Parfit has drawn. If you really believe that creating a new lives barely worth living (or “lives someone would barely choose to live,” in your words) is better than increasing the utility of existing lives then the next logical step is to confiscate all the resources people are using to live standards of life higher than “a life someone would barely choose to live” and use them to make more people instead. That would result in a society identical to the previous one except that it has a lower quality of life and a higher population.
Perhaps it would have sounded a little better if I had said “It is the view that if the only ways Z and A differ is that Z has a higher population, and lower quality of life, then Z is preferable to A, providing that Z’s larger population is large enough that it has higher total utility than A.” I disagree with this of course, it seems to me that total and average utility are both valuable, and one shouldn’t dominate the other.
Also, I’m sorry to have retracted the comment you commented on, I did that before I noticed you had commented on it. I decided that I could explain my ideas more briefly and clearly in a new comment and posted that one in its place.
Okay, I think I finally see where our inferential differences are and why we seem to be talking past each other. I’m retracting my previous comment in favor of this one, which I think explains my view much more clearly.
I interpreted the Repugnant Conclusion to mean that a world with a large population with lives barely worth living is the optimal world, given the various constraints placed on it. In other words, given a world with a set amount of resources, the optimal way to convert those resources to value is to create a huge population with lives barely worth living. I totally disagree with this.
You interpreted the Repugnant Conclusion to mean that a world with a huge population of lives barely worth living may be a better world, but not necessarily the optimal world. I may agree with this.
To use a metaphor imagine a 25 horsepower engine that works at 100% efficiency, generating 25 horsepower. Then imagine a 100 horsepower engine that works at 50% efficiency, generating 50 horsepower. The second engine is better at generating horsepower than the first one, but it is less optimal at generating horsepower, it does not generate it the best it possibly could.
So when you say:
All things equal a world with 50 Utils burning 2 million utils is better than one with 10 utils burning 10.
We can agree say (if you accept my pluralist theory) that the first world is better, but the second one is more optimal. The first world has generated more value, but the second has done a more efficient job of it.
So, if you accept my pluralist theory, we might also say that a population Z, consisting of a galaxy full of 3 quadrillion of people that uses there sources of the galaxy to give them lives barely worth living, would be better than A, a society consisting of planet full of ten billion people that uses the planet’s resources to give its inhabitants very excellent lives. However, Z would be less morally optimal than A because A uses all the resources of the planet to give people excellent lives, while Z squanders its resources creating more people. We could then say that Y, a galaxy full of 1 quadrillion people with very excellent lives is both better than Z and more optimal than Z. We could also say that Y is better than A, and equally optimal as A. However, Y might be worse (but more optimal) than a galaxy with a septillion people living lives barely worth living. Similarly, we might say that A is both more optimal than, and better than B, a planet of 15 billion people living lives barely worth living.
The arguments I have made in the OP have been directed at the idea that a population full of lives barely worth living is the optimal population, the population that converts the resources it has into value most efficiently (assuming you accept my pluralist moral theory’s definition of efficiency). You have been arguing that even if that population is the most efficient at generating value, there might be another population so much huger that it could generate more value, even if it is much less efficient at doing so. I do not see anything contradictory about those two statements. I think that I mistakenly thought you were arguing that such a society would also be more optimal.
And if that is all the Repugnant Conclusion is I fail to see what all the fuss is about. The reason it seemed so repugnant to me was that I thought it argued that a world full of people with lives barely worth living was the very best sort of world, and we should do everything we can to bring such a world about. However, you seem to imply that that isn’t what it means at all. If the Mere Addition Paradox and the Repugnant Conclusion does not imply that we have a moral imperative to bring a vastly populated world about then all it is is a weird thought experiment with no bearing on how people should behave. A curiosity, nothing more.
Even if your argument is a more accurate interpretation of Parfit, I think that idea that a world full of people barely worth living is the optimal one is still a common enough idea that it merits a counterargument. And I think the reason the OP is so heavily upvoted is that many people held the same impression of Parfit that I did.
My argument was against the Mere Addition Paradox, which works by progressively adding more and more people, and the common belief that one of the implications of the MAP is that we have a moral duty to devote all our resources to creating extremely large amounts people.
My main goal is to integrate the common intuition that A+ is better than A with the intuition that creating a vast number of people with low quality of life is bad. Parfit supports the intuition that A+ is better than A by pointing out that the extra people are not doing the inhabitants of A any harm by existing. I point out the reason that this is true is that the extra inhabitants come with their own resources, and that a society with those extra resources, but less people (A++), would be even better.
If each world had the same amount of resources then I’d choose A, it’s the most efficient one at converting resources into overall value.
My understanding of Parfit’s point is that it let you argue that all other things being equal, a huge population with low quality of life is better than a small one with high quality of life. This is what I am trying to refute. Like Unnamed, you don’t seem to think this is necessarily what the MAP implies.
Again, my main point in writing this was to attack the chain of logic that leads from the intuition that adding a few people to A+ will do no harm to the Repugnant Conclusion. In other words, to attack the paradoxical nature of the MAP. I am aware that there are other arguments for the RC that require other responses such as the one about maximizing aggregate utility. Would you buy those cable packages if the government wasn’t forcing you to?
Perhaps I should have started with the pluralist values, since they were sort of the underpinning of my argument. I am basically advocating a system where both creating new lives worth living, improving the utility of those who exist, and possibly other values such as equality, contribute to Overall Value. However, they have diminishing returns relative to each other (if saying that the value of creating a life worth living changes gives you the creeps just keep the value of doing that constant and change the value of the others, it’s essentially the same). I’m not sure if increasing total utility should be a contributing value on its own, or if it is just a side-effect of increasing both the number of lives worth living and the average utility simultaneously.
So the more lives worth living you have, the greater the contributions that enhancing the utility existing lives contributes to overall value. For instance, in a very small population using resources to create a life worth living might contribute 1 Overall Value Point (OVP) while using those same resources to improve existing lives might only produce 0.5 OVPs. However, as the population grows larger, improving existing lives generates more and more OVPs, while creating lives worth living shrinks or remains constant.*
So maybe, if you added a vast amount of lives worth living to a you could generate the same amount of OVP that you could by increasing the average utility just a little. But it would be a fantastically inefficient way to generate OVP. A world where some of the resources used to sustain all those lives were instead used to enhance the lives of those who already exist would be a world with vastly more overall value.
Is this any different from the Zeno’s paradoxes of motion? I.E. you’re basically saying that there is no point where the changes are big enough to become undesirable, so eventually we’ll get to a point that everyone agrees is undesirable. How is that any different from saying Achilles will never catch the tortoise?
*I imagine that actually the values might also change relative to the resources available. Having 8 billion lives worth living on one planet seems like a good amount, but having just 8 billion lives worth living in a whole galaxy seems like a waste.
1) I don’t think anyone in the entire population ethics literature reads Parfit as you do: the moral problem is not one of feasibility via resource constraint, but rather just that Z is a morally preferable state of affairs to A, even if it is not feasible. Again, the paradoxical nature of the MAP is not harmed even if it demands utterly infeasible or even nomologically impossible, but that were we able to actualize Z we should do it.
Regardless, I don’t see how the ‘resource constraint complaint’ you make would trouble the reading of Parfit you make. Parfit could just stipulate that the ‘gain’ in resources required from A to A+ is just an efficiency gain, and so A → Z (or A->B, A->Z) does not involve any increase in consumption. Or we could stipulate the original population in A, although giving up some resources are made happier by knowing there is this second group of people, etc. etc. So it hardly seems necessarily the case that A to A+ demands increased consumption. Denying these alternatives looks like hypothetical fighting.
2) I think the pluralist point stands independently of the resource constraint complaint. But you seem imply a fact you value efficient resource consumption independently: you prefer A because it is a more efficient use of resources, you note there might be diminishing returns to the value of ‘added lives’ so adding lives becomes a merely inefficient way of adding value, etc. Yet I don’t think we should care about efficiency save as an instrument of getting value. All things equal a world with 50 Utils burning 2 million utils is better than one with 10 utils burning 10. So (again) objections to feasibility or efficiency shouldn’t harm the MAP route to the repugnant conclusion.
3) I take your hope for escaping the MAP is getting some sort of weighted sum or combination of total utility, the utility of those who already exist, and possibly average utility of lives will get us our ‘total value’. However, unless you hold that the ‘average term’ or the ‘person affecting’ term are lexically prior to utility (so no amount of utility can compensate for a drop in either), you are still susceptible to a variant of the MAP I gave above:
So the A to A+ move has a small drop in average but a massive gain in utility, and persons already existing gain a boost in their wellbeing (and I can twist the dials even more astronomically). So if we can add these people, redistributing between them such that total value and equality increases seems plausible. And so we’re off to the races. It might be the case that each move demands arbitrarily massive (and inefficient) use resources to actualize—but, again, this is irrelevant to a moral paradox. The only way the diminishing marginal returns point would help avoid MAP if they were asymptotic to some upper bound. However, cashing things out that way looks implausible, and also is vulnerable to intransitivity.
I don’t see the similarity to Zeno’s paradoxes of motion—or, at least, I don’t see how this variant is more similar to Zeno than the original MAP is. Each step from A to A+ to B …. to Z, either originally or in my variant to make life difficult for your view is a step that increases total value. Given transitivity, Z will be better than A. If you think this is unacceptably Zeno like, then you could just make that complaint to the MAP simpliciter (although, FWIW, I think there are sufficient disanalogies as Zeno only works by taking each ‘case’ asymptotically closer to the singularity when tortoise and achilles meet, by contrast MAP is expanding across relevant metrics, so it seems more analogous to a Zeno case where Achilles is ahead of the Tortoise).
The view I am criticizing is not that Z may be preferable to A, under some circumstances. It is the view that if the only ways Z and A differ is that Z has a higher population, and lower quality of life, then Z is preferable to A. This may not be how Parfit is correctly interpreted, but it is a common enough interpretation that I think it needs to be attacked.
Again, my complaint with the paradox is not that, if Z and A are our only choices, that A is preferable to Z. Rather my complaint is the interpretation that if we were given some other alternative, Y that has a much larger population than A, but a smaller population and higher quality of life than Z, that Z would be preferable to Y as well.
Again, I admitted that my solution might allow a MAP route to the repugnant conclusion under some instances like the one you describe. My main argument is that under circumstances where our choices are not constrained in such a manner, it is better to pick a society with a higher quality of life and lower population.
Again, my objection is not that going this route is preferable is the best choice if it is the only choice we are allowed. My objection is to people who interpret Parfit to mean that even under circumstances where we are not in such a hypothetical and have more option to choose from, we should still choose the world with lives barely worth living (i.e. Robin Hanson). Again, those people may be interpreting Parfit incorrectly, which in turn makes my criticism seem like an incorrect interpretation of Parfit. But I think it is a common enough view that it deserves criticism.
In light of your and Unnamed’s comments I have edited my post and added an explanatory paragraph at the beginning, which says:
“EDIT: To make this clearer, the interpretation of the Mere Addition Paradox this post is intended to criticize is the belief that two societies that differ in no way other than that one has a higher population and lower quality of life than the other, that that society is necessarily better than the one with the lower population and higher quality of life. Several commenters have argued that this is not a correct interpretation of the Mere Addition Paradox. They seem to claim that a more correct interpretation is that a sufficiently large population with a lower quality of life is better than a smaller one with a higher quality of life, but that it may need to differ in other ways (such as access to resources) to be truly better. They may be right, but I think that it is still a common enough interpretation that it needs attacking. The main practical difference between the interpretation that I am attacking and the interpretation they hold is that the former confers a moral obligation to create as many people as possible, regardless of its effects on quality of life, but the later does not.”
Let me know if that deals sufficiently with your objections.
″ It is the view that if the only ways Z and A differ is that Z has a higher population, and lower quality of life, then Z is preferable to A. This may not be how Parfit is correctly interpreted, but it is a common enough interpretation that I think it needs to be attacked.”
Generally it’s a good idea to think twice and reread before assuming that a published and frequently cited paper is saying something so obviously stupid.
Your edit doesn’t help much at all. You talk about what others “seem to claim”, but the argument that you have claimed Parfit is making is so obviously nonsensical, that it would lead me to wonder why anyone cites his paper at all, or why any philosophers or mathematicians have bothered to refute or support it’s conclusions with more than a passing snark. A quick google search on the term “Repugnant Conclusion” leads to a wikipedia page that is far more informative than anything you have written here.
It doesn’t seem any less obviously stupid to me then the more moderate conclusion you claim that Parfit has drawn. If you really believe that creating a new lives barely worth living (or “lives someone would barely choose to live,” in your words) is better than increasing the utility of existing lives then the next logical step is to confiscate all the resources people are using to live standards of life higher than “a life someone would barely choose to live” and use them to make more people instead. That would result in a society identical to the previous one except that it has a lower quality of life and a higher population.
Perhaps it would have sounded a little better if I had said “It is the view that if the only ways Z and A differ is that Z has a higher population, and lower quality of life, then Z is preferable to A, providing that Z’s larger population is large enough that it has higher total utility than A.” I disagree with this of course, it seems to me that total and average utility are both valuable, and one shouldn’t dominate the other.
Also, I’m sorry to have retracted the comment you commented on, I did that before I noticed you had commented on it. I decided that I could explain my ideas more briefly and clearly in a new comment and posted that one in its place.
Okay, I think I finally see where our inferential differences are and why we seem to be talking past each other. I’m retracting my previous comment in favor of this one, which I think explains my view much more clearly.
I interpreted the Repugnant Conclusion to mean that a world with a large population with lives barely worth living is the optimal world, given the various constraints placed on it. In other words, given a world with a set amount of resources, the optimal way to convert those resources to value is to create a huge population with lives barely worth living. I totally disagree with this.
You interpreted the Repugnant Conclusion to mean that a world with a huge population of lives barely worth living may be a better world, but not necessarily the optimal world. I may agree with this.
To use a metaphor imagine a 25 horsepower engine that works at 100% efficiency, generating 25 horsepower. Then imagine a 100 horsepower engine that works at 50% efficiency, generating 50 horsepower. The second engine is better at generating horsepower than the first one, but it is less optimal at generating horsepower, it does not generate it the best it possibly could.
So when you say:
We can agree say (if you accept my pluralist theory) that the first world is better, but the second one is more optimal. The first world has generated more value, but the second has done a more efficient job of it.
So, if you accept my pluralist theory, we might also say that a population Z, consisting of a galaxy full of 3 quadrillion of people that uses there sources of the galaxy to give them lives barely worth living, would be better than A, a society consisting of planet full of ten billion people that uses the planet’s resources to give its inhabitants very excellent lives. However, Z would be less morally optimal than A because A uses all the resources of the planet to give people excellent lives, while Z squanders its resources creating more people. We could then say that Y, a galaxy full of 1 quadrillion people with very excellent lives is both better than Z and more optimal than Z. We could also say that Y is better than A, and equally optimal as A. However, Y might be worse (but more optimal) than a galaxy with a septillion people living lives barely worth living. Similarly, we might say that A is both more optimal than, and better than B, a planet of 15 billion people living lives barely worth living.
The arguments I have made in the OP have been directed at the idea that a population full of lives barely worth living is the optimal population, the population that converts the resources it has into value most efficiently (assuming you accept my pluralist moral theory’s definition of efficiency). You have been arguing that even if that population is the most efficient at generating value, there might be another population so much huger that it could generate more value, even if it is much less efficient at doing so. I do not see anything contradictory about those two statements. I think that I mistakenly thought you were arguing that such a society would also be more optimal.
And if that is all the Repugnant Conclusion is I fail to see what all the fuss is about. The reason it seemed so repugnant to me was that I thought it argued that a world full of people with lives barely worth living was the very best sort of world, and we should do everything we can to bring such a world about. However, you seem to imply that that isn’t what it means at all. If the Mere Addition Paradox and the Repugnant Conclusion does not imply that we have a moral imperative to bring a vastly populated world about then all it is is a weird thought experiment with no bearing on how people should behave. A curiosity, nothing more.
Even if your argument is a more accurate interpretation of Parfit, I think that idea that a world full of people barely worth living is the optimal one is still a common enough idea that it merits a counterargument. And I think the reason the OP is so heavily upvoted is that many people held the same impression of Parfit that I did.