Key Arguments

• Parfit extends the earlier A vs B comparison to a whole sequence A, B, C, …, Z, noting that 'On the Impersonal Total Principle, just as B would be better than A, C would be better than B. And Z might be best.'
• He characterizes Z as 'some enormous population whose members have lives that are not much above the level where life ceases to be worth living', and explains that 'if the numbers are large enough, this is the outcome with the greatest total sum of happiness.'
• He explicitly formulates the Repugnant Conclusion: 'For any possible population of at least ten billion people, all with a very high quality of life, there must be some much larger imaginable population whose existence, if other things are equal, would be better, even though its members have lives that are barely worth living.'
• He underlines his own evaluative reaction—'As my choice of name suggests, I find this conclusion hard to accept.'—to indicate that this implication is a serious cost for the Impersonal Total Principle.
• He notes that Z could also be 'the outcome in which there is the greatest quantity of whatever makes life worth living', so the problem persists for non‑hedonistic total views that aggregate 'whatever makes life worth living', not just happiness.

Source Quotes

THEREPUGNANT CONCLUSION Consider next the larger diagram below. On the Impersonal Total Principle, just as B would be better than A, C would be better than B. And Z might be best. Z is some enormous population whose members have lives that are not much above the level where life ceases to be worth living.

And Z might be best. Z is some enormous population whose members have lives that are not much above the level where life ceases to be worth living. A life could be like this either because it has enough ecstasies to make its agonies seem just worth enduring, or because it is uniformly of poor quality.

Let us imagine the lives in Z to be of this second drabber kind. In each of these lives there is very little happiness. But, if the numbers are large enough, this is the outcome with the greatest total sum of happiness. Similarly, Z could be the outcome in which there is the greatest quantity of whatever makes life worth living.

But, if the numbers are large enough, this is the outcome with the greatest total sum of happiness. Similarly, Z could be the outcome in which there is the greatest quantity of whatever makes life worth living. (The greatest mass of milk might be found in a heap of bottles each containing only a single drop.) Let us next assume, for a reason that I shall later give, that A would have a population of ten billion.

(The greatest mass of milk might be found in a heap of bottles each containing only a single drop.) Let us next assume, for a reason that I shall later give, that A would have a population of ten billion. The Impersonal Total Principle then implies The Repugnant Conclusion: For any possible population of at least ten billion people, all with a very high quality of life, there must be some much larger imaginable population whose existence, if other things are equal, would be better, even though its members have lives that are barely worth living. As my choice of name suggests, I find this conclusion hard to accept. A and B could in practice be real alternatives.

Key Concepts

• On the Impersonal Total Principle, just as B would be better than A, C would be better than B. And Z might be best.
• Z is some enormous population whose members have lives that are not much above the level where life ceases to be worth living.
• In each of these lives there is very little happiness. But, if the numbers are large enough, this is the outcome with the greatest total sum of happiness.
• Similarly, Z could be the outcome in which there is the greatest quantity of whatever makes life worth living.
• The Repugnant Conclusion: For any possible population of at least ten billion people, all with a very high quality of life, there must be some much larger imaginable population whose existence, if other things are equal, would be better, even though its members have lives that are barely worth living. As my choice of name suggests, I find this conclusion hard to accept.

Context

Opening of Section 131 ('THEREPUGNANT CONCLUSION'), where Parfit applies the Impersonal Total Principle to a stylized diagram of populations A, B, C, …, Z and states the Repugnant Conclusion as a direct implication of total utilitarian aggregation over population size.