"Whoever saves a single life, it is as if he had saved the whole world."
– The Talmud, Sanhedrin 4:5
It's a beautiful thought, isn't it? Feel that warm glow.
I can testify that helping one person feels just as good as helping the whole world. Once upon a time, when I was burned out for the day and wasting time on the Internet - it's a bit complicated, but essentially, I managed to turn someone's whole life around by leaving an anonymous blog comment. I wasn't expecting it to have an effect that large, but it did. When I discovered what I had accomplished, it gave me a tremendous high. The euphoria lasted through that day and into the night, only wearing off somewhat the next morning. It felt just as good (this is the scary part) as the euphoria of a major scientific insight, which had previously been my best referent for what it might feel like to do drugs.
Saving one life probably does feel just as good as being the first person to realize what makes the stars shine. It probably does feel just as good as saving the entire world.
But if you ever have a choice, dear reader, between saving a single life and saving the whole world - then save the world. Please. Because beyond that warm glow is one heck of a gigantic difference.
For some people, the notion that saving the world is significantly better than saving one human life will be obvious, like saying that six billion dollars is worth more than one dollar, or that six cubic kilometers of gold weighs more than one cubic meter of gold. (And never mind the expected value of posterity.) Why might it not be obvious? Well, suppose there's a qualitative duty to save what lives you can - then someone who saves the world, and someone who saves one human life, are just fulfilling the same duty. Or suppose that we follow the Greek conception of personal virtue, rather than consequentialism; someone who saves the world is virtuous, but not six billion times as virtuous as someone who saves one human life. Or perhaps the value of one human life is already too great to comprehend - so that the passing grief we experience at funerals is an infinitesimal underestimate of what is lost - and thus passing to the entire world changes little.
I agree that one human life is of unimaginably high value. I also hold that two human lives are twice as unimaginably valuable. Or to put it another way: Whoever saves one life, if it is as if they had saved the whole world; whoever saves ten lives, it is as if they had saved ten worlds. Whoever actually saves the whole world - not to be confused with pretend rhetorical saving the world - it is as if they had saved an intergalactic civilization.
Two deaf children are sleeping on the railroad tracks, the train speeding down; you see this, but you are too far away to save the child. I'm nearby, within reach, so I leap forward and drag one child off the railroad tracks - and then stop, calmly sipping a Diet Pepsi as the train bears down on the second child. "Quick!" you scream to me. "Do something!" But (I call back) I already saved one child from the train tracks, and thus I am "unimaginably" far ahead on points. Whether I save the second child, or not, I will still be credited with an "unimaginably" good deed. Thus, I have no further motive to act. Doesn't sound right, does it?
Why should it be any different if a philanthropist spends $10 million on curing a rare but spectacularly fatal disease which afflicts only a hundred people planetwide, when the same money has an equal probability of producing a cure for a less spectacular disease that kills 10% of 100,000 people? I don't think it is different. When human lives are at stake, we have a duty to maximize, not satisfice; and this duty has the same strength as the original duty to save lives. Whoever knowingly chooses to save one life, when they could have saved two - to say nothing of a thousand lives, or a world - they have damned themselves as thoroughly as any murderer.
Addendum: It's not cognitively easy to spend money to save lives, since cliche methods that instantly leap to mind don't work or are counterproductive. (I will post later on why this tends to be so.) Stuart Armstrong also points out that if we are to disdain the philanthropist who spends life-saving money inefficiently, we should be consistent and disdain more those who could spend money to save lives but don't.
I know I'm way behind for this comment, but still: this point of view makes sense on a level, that saving additional people is always(?) virtuous and you don't hit a ceiling of utility. But, and this is a big one, this is mostly a very simplistic model of virtue calculous, and the things it neglected turn out to have a huge and dangerous impact.
First case in point: can a surgeon harvest organs from a healthy innocent bystander to save the lives of five people in dire need of those organs? Assuming they match and there is no there donor, an unfortunately likely incident. According to this, we must say that they not only can, but should, since the surgeon is damned as a murderer either way, so at least stack the lower number of bodies. I hope I don't need to explain that this goes south. This teaches us that there must be some distinction between taking negative action and avoiding a (net) positive one.
Another case: suppose I'm in a position to save lives on a daily basis, e.g. an ER doctor. Then if a life not saved is a life lost, then every hour that I rest, or you know, have fun, is another dead body on my scoreboard. Same goes for anyone doing their best to save lives, but in any way other than the single optimal one with the maximal expected number of lives. This one optimal route, if we're not allowed to rest, leads to burnout very quickly and loses lives on the long run. So we must find (immediately!) the One Best Way, or be doomed to be perpetual mass murderers.
As Zach Weinersmith (and probably others) once said, "the deep lesson to learn from opportunity cost is that we're all living every second of our lives suboptimally". We're not very efficient accuracy engines, and most likely not physically able to carry out any particular plan to perfection (or even close), so almost all of the time we'll get things at least somewhat wrong. So we'll definitely be mass murderers by way of failing to save lives, but... Then... Aren't we better off dead? And then are lives lost really that bad...?
And you can't really patch this neatly. You can't say that it's only murder if you know how to save them, because then the ethical thing would be to be very stupid and unable to determine how to save anyone. This is also related to a problem I have with the Rationalist Scoreboard of log(p) that Laplace runs at the Great Spreadsheet Above.
And even if you try to fix this by allowing that we maintain ourselves to save more lives in the long run, we 1) don't know exactly how much this should be, and 2) doing our best attempt at this is going to end up with everyone being miserable, just trying to maximize lives but not actually living them, since pain/harm is typically much easier to produce and more intense than pleasure.
And, of course, all of this is before we consider human biases and social dynamics. If we condemn the millionaire who saves lives inefficiently, we're probably drawing attention from the many others who don't even do that. Since it's much easier to be exposed to criticism than earn praise in this avenue (and this in the broad sense is a strong motivation for people to try and be virtuous), many people would see this and give up altogether.
The list goes on, but my rant can only go so long, and I hope that some of the holes in this approach are now more transparent.