Does that mean we should spend more of our altruistic energies on encouraging happy productive people to have more happy productive children?
Maybe. I think the realistic problem with this strategy is that if you take an existing human and help him in some obvious way, then it's easy to see and measure the good you're doing. It sounds pretty hard to figure out how effectively or reliably you can encourage people to have happy productive children. In your thought experiment, you kill the hermit with 100% certainty, but creating a longer, happier life that didn't detract from others' was a complicated conjunction of things that worked out well.
Haven't had one of these for awhile. This thread is for questions or comments that you've felt silly about not knowing/understanding. Let's try to exchange info that seems obvious, knowing that due to the illusion of transparency it really isn't so obvious!