Not an intrusion at all. Your questions/considerations regarding principles at work bring us ever deeper into philosophy -- never a bad thing, because most don't consider philosophy very deeply, as fundamental as it is to one's worldview.
However, to start, you say: "If there is a principle at work, a routine, a way of behaving, so as to avoid abandoning the victim, which may be the victim abandoning his or her own self, or someone nearby letting the victim suffer without doing anything to help, and having that principle work, in any case, or every case, or most cases..."
This premise, as I will call it, is pregnant with assumptions. The way the question is posed carries a bias in favor of the victim; but we should not presume the passersby shouldn't abandon said victim. That is a value judgment. It is likewise with respect to someone nearby letting the victim suffer; we may disagree with their decision, but we are not in a position to judge the reasons and values which caused that someone nearby not to intervene on behalf of the suffering victim; and we are in less a position to compel them to action based on our own value judgments.
The principle at work, then, I would contend (as always), is self-ownership. This principle does not assert in any manner that life is or should be fair to any extent; only that your body is yours, and you may do whatsoever you please with it provided you are not aggressing against that of another.
As for the practical enforcement of this principle? There is none. It all sounds well and good, but we live in an imperfect world. I would just prefer my imperfect world to be decentralized to the greatest extent possible, as I believe the evidence over the course of history shows clearly and overwhelmingly that the worst of mankind is manifest in centralized societies; and conversely, the most peaceful and productive state of mankind is fostered in disaggregated, improvisational living, where responsibility is assumed rather than delegated or dictated.
In this way, I believe this principle would best suit your scenario's victims, as well as everyone else; simply based on the environment it would foster, which is beyond the imagination of most at this point because of how far down the other path we are.
Want DP delivered to your inbox daily? Subscribe here: