From Derek Parfit's On What Matters, chapter 126 (Has It All Been Worth It?):
> If someone dies a slow and painful death, it would have been both better for this person, and impersonally better, if this person’s life had ended earlier. The last part of this person’s life was worse than nothing, or in itself bad. We can reach similar conclusions about the whole of someone’s life. If someone’s life contains much prolonged suffering, and nothing or little that is good, it would have been both better for this person, and impersonally better, if this person’s life had ended just after it started. Things may be in one way different if we suppose instead that this person’s life had never even started. Perhaps we could not claim that this alternative would have been better for this person. But when we ask which alternative would have been impersonally better, there is little difference between these two comparisons. Since it would have been better if this person’s life had stopped just after it started, it would also have been better if this person’s life had never started. In other words, it would have been impersonally better if this wretched person had never existed. And since such claims make sense when applied to one person, they also make sense when applied to all conscious beings, or to the whole of reality.
Parfit thinks it was/is worth it, given the good things in life, and using future improvements in QoL as one of the arguments.
I don't. What amount of pathos, pleasure, love, beauty, could justify the life and suffering of even one person who say, was raped and murdered in childhood? It would be very difficult to justify the creation of a world given that tradeoff, but people are much hesitant to accept that it is unjustified now that it already exists.