> The fork one? They still don't exist.
I am hardly the first person to make decisions about my actions based on the welfare of people who do not yet exist. Many reasonable people agree that we owe it to future humans (people who do not exist), to leave the Earth more or less habitable for them.
> Are you trying your best? Are you pregnant right now?
I am literally typing this reply while holding my 8 day old son. He is my third child. I'm sure some could quibble with the level of my effort, but we plan to have more and, well, 3 is greater than 0.
By the way, this N+1 argument is not a refutation of my argument. If there are a bunch of people drowning after a boat capsizes, do you choose not to rescue any of them just because you cannot rescue all of them?
No, you get in there and rescue as many as you can. Afterwards, you agonize about whether or not you could have saved more if you had done this or that differently. Eventually, you come to terms with how things worked out and your inadequacy as a human being.
> If you're a male, why are you not in a polyamorous relationship?
It generally takes two people to make a baby. The female's willingness to make a baby is usually inversely correlated with her belief that the male has relationships with other females.
So either the guy really lucks out, or (more commonly) polygamy involves a level of coercion or deception that conflicts with basic decency.