The Importance of Permissions Not to Help

If there were no costs involved at all, then I don't think this could happen. Then I think you'd just be required to save the greater number. But in some cases, so take the bolder case again, suppose that you've got a boulder headed toward one person and five other people. The only way to stop one of the boulders is by putting your leg or both of your legs in front of one boulder or the other. So it would be permissible for you to just do nothing in that case. It wouldn't extend to saving the one at the cost of your legs because there's no difference between saving the one and saving the five.