As with Torture vs. Specks, the point of this is to expose your decision procedure in a context where you don’t have to compare remotely commensurable utilities. Learning about the behavior of your preferences at such an extreme can help illuminate the right thing to do in more plausible contexts. (Thinking through Torture vs. Dust Specks helped mold my thinking on public policy, where it’s very tempting to weigh the salience of a large benefit to a few people against a small cost to everyone.)
EDIT: It’s the same heuristic that mathematicians often use when we’re pondering a conjecture— we try it in extreme or limiting cases to see if it breaks.
As with Torture vs. Specks, the point of this is to expose your decision procedure in a context where you don’t have to compare remotely commensurable utilities. Learning about the behavior of your preferences at such an extreme can help illuminate the right thing to do in more plausible contexts. (Thinking through Torture vs. Dust Specks helped mold my thinking on public policy, where it’s very tempting to weigh the salience of a large benefit to a few people against a small cost to everyone.)
EDIT: It’s the same heuristic that mathematicians often use when we’re pondering a conjecture— we try it in extreme or limiting cases to see if it breaks.