Situation A: 12-year-old Emma leads a happy life and gains U > 0 utility.
Situation B: Emma is continually raped and tortured for an online audience of consumers of sadistic child pornography. She loses L ≫ 0 utility. Each audience member gains 0 < ε ≪ L utility.
By the Archimedean property, there is some number of audience members N such that N·ε > L and even N·ε - L > U, namely N = ⌈(L + U + 1)/ε⌉. Thus, by simply increasing the number of audience members, B becomes preferable to A . This is true no matter how immense Emma's suffering or how negligible each audience member's enjoyment is.
This example seems to be a reductio against using aggregate utility as a basis for ethics. Has it been discussed in the literature? Which situation do you find preferable?