One fashionable notion among some of the intel ligentsia is that old peo ple have "a duty to die," rather than become a burden to others. This is more than just an idea discussed around a seminar table. Already Britain's government-run medical system is restricting what medications or treatments it will authorize for the elderly. It seems almost certain that similar attempts to contain runaway costs will lead to similar policies when US medical care is taken over by the government. Make no mistake: Letting old people die is a lot cheaper than spending the kind of money required to...