"What's the worst that can happen?" goes the optimistic saying. It's probably a bad question to ask anyone with a creative imagination. Let's consider the problem on an individual level: it's not really the worst that can happen, but would nonetheless be fairly bad, if you were horribly tortured for a number of years. This is one of the worse things that can realistically happen to one person in today's world.
What's the least bad, bad thing that can happen? Well, suppose a dust speck floated into your eye and irritated it just a little, for a fraction of a second, barely enough to make you notice before you blink and wipe away the dust speck.
For our next ingredient, we need a large number. Let's use 3^^^3, written in Knuth's up-arrow notation:
- 3^3 = 27.
- 3^^3 = (3^(3^3)) = 3^27 = 7625597484987.
- 3^^^3 = (3^^(3^^3)) = 3^^7625597484987 = (3^(3^(3^(... 7625597484987 times ...)))).
3^^^3 is an exponential tower of 3s which is 7,625,597,484,987 layers tall. You start with 1; raise 3 to the power of 1 to get 3; raise 3 to the power of 3 to get 27; raise 3 to the power of 27 to get 7625597484987; raise 3 to the power of 7625597484987 to get a number much larger than the number of atoms in the universe, but which could still be written down in base 10, on 100 square kilometers of paper; then raise 3 to that power; and continue until you've exponentiated 7625597484987 times. That's 3^^^3. It's the smallest simple inconceivably huge number I know.
Now here's the moral dilemma. If neither event is going to happen to you personally, but you still had to choose one or the other:
Would you prefer that one person be horribly tortured for fifty years without hope or rest, or that 3^^^3 people get dust specks in their eyes?
I think the answer is obvious. How about you?
Where there are no special inflection points, a bad repeated action should be a bad individual action, a good repeated action should be a good individual action. Talking about the repeated case changes your intuitions and gets around your scope insensitivity, it doesn't change the normative shape of the problem (IMHO).
Hmm, I see your point. I can't help like feeling that there are cases where repetition does matter, though. For instance, assuming for a moment that radical life-extension and the Singularity and all that won't happen, and assuming that we consider humanity's continued existence to be a valuable thing - how about the choice of having/not having children? Not having children causes a very small harm to everybody else in the same generation (they'll have less people supporting them when old). Doesn't your reasoning imply that every couple should be forced into having children even if they weren't of the type who'd want that (the "torture" option), to avoid causing a small harm to all the others? This even though society could continue to function without major trouble even if a fraction of the population did choose to remain childfree, for as long as sufficiently many others had enough children?