@Robin,

"But even though there are 26 comments here, and many of them probably know in their hearts torture is the right choice, no one but me has said so yet."

I thought that Sebastian Hagen and I had said it. Or do you think we gave weasel answers? Mine was only contingent on my math being correct, and I thought his was similarly clear.

Perhaps I was unclear in a different way. By asking if the choice was repeatable, I didn't mean to dodge the question; I meant to make it more vivid. Moral questions are asked in a situation where many people are making moral choices all the time. If dust-speck displeasure is additive, then we should evaluate our choices based on their potential aggregate effects.

Essentially, it's a same-ratio problem, like showing that 6:4::9:6, because 6x3=9x2 and 4x3=6x2. If the aggregate of dust-specking can ever be greater than the equivalent aggregate of torturing, then it is always greater.