Most philosophers who've delved into population ethics claim it's an incredibly challenging field. This has led some thinkers, including Derek Parfit, to step away from the discipline altogether
Hedons, used in examples below, represent units of happiness.
Main source: Reasons and persons by Darek Parfit
You take total sum of each persons hedons.
Problems
Repugnant conclusion. Let’s imagine we have a society one at one million people with 99 hedons each. There is also society two. The bar of life worth living is at 10 hedons. People in that society has 11 headons each.
If the second society population is larger than 9 mln it has more hedons than the society one and is a preferable outcome.
Notes
Position of a lot of positive psychologist. It’s less about making people happy, but it is about making happy people.
You take an average of hedons of all people.
Problems
One life of a person with 100 headons is worth more than 1 million lives of people that all have 99 headons. The average of first is larger.
It makes an immoral act to add live that is below average. Because this action would lower the average of all the group.
It also makes it ethical to kill people that are below average to rise the average.
Will MacAskill on Sam Harris Show
Michael Plant thinks that adding more happy people isn’t an ethical act. See Intuition of neutrality