Then 10 billion people with 1.1 happiness each yield 11 billion total happiness. They are, collectively, happier.
And 100 billion people with 0.111 happiness each are, collectively, even happier.
And 1 trillion people with 0.01111 happiness each are, collectively, even happier.
Etc, etc.
The ‘repugnant conclusion’ is that this sequence never ends. You can argue for ever higher populations based on total happiness even though individual happiness approaches zero.
It’s obvious nonsense.
But happiness is not even a quantity, it is a direction. It is not a destination, it is a journey. Those who arrive at a destination where they think they will find happiness, without having a new destination to seek, inevitably become stagnant and miserable. You can't define a linear sum on such a phenomenon.
Or a billion people with one happiness each are almost exactly equal to one person with a billion happiness and a billion people with 0 happiness?
It's not so much repugnant as ridiculous.
Exactly. Philosophers should be required to take courses in abstract algebra and topology before being allowed to discuss utilitarianism.
Consider two sentient species that evolved on two different planets in two different galaxies. One species decides to prioritize minimum happiness: the result is that they have 1 billion people, each of whom live the fabled lives of gods: everyone has constant access to physical and intellectual pleasures (food, music, whatever), is completely free of disease, war, and so on. Nobody ever thinks of suicide because they're just so blissfully happy and satisfied all the time. But to achieve this, they limit their population such that it never grows past 1 billion.
Another species decides to maximize aggregate happiness. They expand to have the maximum number of their species possible while maintaining a positive "happiness balance" for each person. Each person's life is hard, full of pain and toil; it's also rewarding, full of joy and relationships; but the reward is only ever fractionally better than the sorrow. Obviously that's an average: people's lives always have ups and downs, and during the "down" times, people begin to contemplate suicide. People may spend as much as 45% of their lives feeling that life isn't really worth living. But there are far more of them -- they've expanded to every available liveable location nearby, and continue to grow. There are trillions of them already, and as they continue to expand throughout their galaxy, there will be trillions upon trillions more.
So which species has made a better choice? When concretely embodied like this, I don't think the question is a nonsense one at all.
The only part I think might be considered nonsense is the assumption that you can always have one more and still have an average/minimum positive utility. Consider a generation spaceship (i.e., a spaceship designed to take several generations to travel between stars) with enough replicators to generate food for 1000 people to be sated. Some people might consider 1200 usually-hungry-but-otherwise-happy people is better than 1000 always-sated people, but 3000 always-starving people must be far worse; and 100,000 people living on the calories of 1000 people is clearly physically impossible.
The same thing goes for means, weighted means, and so forth. The classic joke being that when Bill Gates walks into a homeless shelter, everyone is a millionaire on averages.