Related to the threads: https://www.physicsforums.com/showthread.php?t=42126 https://www.physicsforums.com/showthread.php?t=42223 Nation X has been killing its citizens by the thousand, stuffing them into mass graves. The estimated death toll is 500,000, and looks like it will reach a million within ten years. Nation Y wishes to invade. For the purposes of this question, let's assume Nation Y's motives are entirely to do with saving lives, and there is nothing else to be gained from invading. Heck, maybe it will even be a financial loss for all involved. Either way, Nation Y wants to invade, destroy the government of Nation X, and prevent further murders. However, Nation Y predicts that the invasion will cost the life of ONE innocent person. That person is known to Nation Y. That person is your wife, husband, brother, sister, or child. The person is just some innocent civilian, and has nothing whatsoever to do with the governing of Nation X. Just one innocent person. That person has no idea that he/she may be the unlucky one involved. Is it right for Nation Y to invade Nation X?