I must admit I do not really like the story mentioned in my previous post. Asimov is one of my very favourite SF writers, but The Winnowing seems to be too schematic for a Writer like that; I find it poorer than, say, The Dwindling Sphere by Willard Hawkins, let alone Make Room! Make Room! by Harry Harrison (only in this case I rather mean Soylent Green, which is not a story but a movie, which, of course, is not really by Harrison).
I also disagree about the Earth being a lifeboat. It is more like a rich cruiser reduced to some floating leaky asylum by stupid and greedy crew and even more stupid passengers.
But I do agree the people in the lifeboat are armed and therefore dangerous to the self-appointed well-fed Saviours. Makes triaging difficult, too. And that`s the important thing the Author ignores, barely touching upon it.
Matter is, some people and most (if not all) peoples are still armed. I suppose thence the ubiquitous efforts to disarm them, physically and mentally, or at least legally. Once the floating Broadmoor patients are disarmed, the Rescuers can triage to their heart`s content!
:D