Throwing people overboard is analogous to killing. Not reproducing isn't killing. Bad analogy. Look at it more like we're on a cruise liner lost eternally at sea. Sure, there's a garden on deck that supplies food, but it only supplies enough for X people. And the fuel is limited. Wait, that's not really metaphorical at all. That's almost the literal situation earth faces.

But, yeah, patch the raft. And stop having 4 kids.