for example, let's say that if we kill one old sick woman, it will save the lives of ten younger, healthier people... is it okay to do that?
Kant argues that it isn't just about the utility of the question -- it's also about the social contracts we are willing to live with, knowing that we might be on the other side of that coin at some point -- and we want to know that we are not going to be arbitrarily axed just because our loss is 10 people's gain
those social contracts are also quite relevant in the face of the disasters like Katrina ... watching the people there suffer and not be cared for makes us all feel more vulnerable ... we think there is a contract that the powers that be will provide certain kinds of assistance in emergencies ... when that doesn't happen, everyone's confidence is eroded ... would it save money for the country if we just let those people go? maybe so, but if we do not take care of all, even "the least of these," then who knows but what we might someday fall into that category.
apologies for the soapbox -- moral philosophy was one of my favorite college classes and my ears perk up whenever I see an application of this particular question! :)
as for torture of a villainous informant, the torture might be justified by his villainy but not by the numbers of people it might save -- does that make sense?