Sure, it's murder. But I suspect most people would, on occasion, find justification to murder in order to save lives (or even just to save "more important" liv

Sure, it's murder. But I suspect most people would, on occasion, find justification to murder in order to save lives (or even just to save "more important" lives - wars are fought all the time on the theory that the lives of a country's citizens are more important than the lives of foreigners). On reflection, perhaps a better reframing of this thought experiment (to avoid many of the issues that others have brought up) would be that a murderer has broken into your house and tied you up, along with a baby and a highly accomplished but relatively young person, and offers you the choice of which one of the others he's going to kill, along with a credible assurance that he'll kill all of you if you don't choose one (and you're not allowed to pick yourself, just because), and he'll really let the remaining two of you free once you've made a choice. Further, you're not allowed to discuss with the others, so there's no opportunity for anyone to sacrifice themselves.